EFFECT OF FOLIAR FERTILIZATION OF POTASSIUM ON GROWTH, YIELD AND NUTRIENTS CONTENT OF BRRI dhan29
UNDER DIFFERENT SALINITY A Thesis
n
MD. SIIAMIM AL MAMUN
Reg. No. 10-04040
SubmittetIto the 'Department of)4griculiura(Cfiemistry S/ier-e4angIa J2lgr
icu
lturaWntversity, (Dfia&ain partiafflulfihiment of tEe requirements for the Legree of
MASTER OF SCIENCE (M.S.) IN
AGRICULTURAL CHEMISTRY Semester: Jan-June, 2016
APPROVED BY:
4 Supervisor ....4. Co-supervisor (Dr. Sheikh Shawkat Zamil)
Associate Professor
Department of Agricultural Chemistry Sher-e-Bangla Agricultural University,
(Dr. Md. Abdur Razzaque) Professor
Department of Agricultural Chemistry Sher-e-Bangla Agricultural University,
Dhaka-1207 Dhaka-1207
pA
(Dr. Mohammed Ariful Islam) Chairman
Examination committee
'A
DEPARTMENT OF AGRICULTURAL CHEMISTRY
Sher-e-Bangla Agricultural University
Sher- e- Bangla Nagar, Dhaka-1207Ref. No: Date:
J7q2IflqtE
This is to certify that thesis entitled, 'Er ETOcF fOLt*c'<JPEVZLTZ.4 710W Of qorssrvs3f OW gJYW1% 'flntv AWD WV*J'EWJY CO!W!EflO'F (BflJ dHan29 V9V!D!EVDIe?ERE2v1TSfifJJV7tYSUbmitted to the
IH;'Jji:'!L1:\7 )/:L1TLAiL H/ •IH.c!k
, Sher-e-Bangla Agricultural University, Dhaka in partial fulfillment of the requirements for the degree of 111ASTE R.
ors(/L:\'r'r:
(:11.5.)in
21(9)1(L}LJ?jiLj1:V/YTRYembodieS the result of a piece of bona fit/c research work carried out by MD. SHAMIM AL MAMUN Rcg
ru!/'n Alt/0-04040 under my supervision and guidance. No part of the thesis has been submitted for any other degree or diploma.
I further certify that such help or source of information, as has been availed of during the course of this investigation has duly been acknowledged by him.
\ e.
Date: ...
Place: Dhaka, Bangladesh Supervisor
(Dr. Sheikh Shawkat Zamil) Associate Professor
Department of Agricultural Chemistry
ACKNOWLEDGEMENTS
All the praises, gratitude and thankc are due to the omniscient, omnipresent and omnipotent Allah who enabled inc to complete this thesis work successfully for my MS degree.
I wish to express my sincere appreciation and profound grat itude and best regards to n' reverend supervisor Associate Prof Dr. Sheik/s Shawkat Zamil. Department
of
Agricultural Chemistry, Sher-e-Iiangla Agricultural University, Sher-e-J3angla Nagar, Dhaka- 1207 for his scholastic guida, ice. innovative suggestion, constant supervision and inspiration, valuable advice and helpfid criticism in carrying out the research work and preparationof
this manuscript.I deem it a proud privilege to acknowledge my grateflulness, boundless gratitude and best regards to my respectable co-supervisor Prof. Dr. Md. Abdur Razzaque, Department
of
Agricultural Chemistry, Sher-e-Bangla Agricultural University. Sher.e-Bangla Nagar, Dhaka. 1207 for his valuable advice, constructive criticism andfactual comments in upgrading the research work.It is a great pleasure ami privilege to express my profound gratitude and sincere regards to Associate Prof Dr. Mohammed Arjful Islam, Chairman, Department
of
Agricultural Chemistry, Slier-c-Bang/a Agricultural University, Dhaka .1207 for his help, heartiest co.operazion, efficient guidance, valuable advice, constructive criticism andfacilities and supports needed to undertake this research workSpecial appreciation and warmest gratitude are extended to m,v estee,ned teachers Prof Dr. kid.
Azizur Rahinan Mazumder and Prof Dr. Rokeya Beguni Department
of
Agricultural Chemistry, She r.e.Bangla Agricultural University, Dhaka who provided creative suggestions, guidance and constant inspirationfrom the beginning to the completionof
the research work Their contribution, love and qifection tvould persist in my memory for countless days.I wish to express my cordial than/cs to Departmental and field staffs for their active help during the experimental period
I express my unfathomable tributes, sincere gratitude and heartfelt indebtedness from my core
of
heart to my father Md. Zahirul Haque, mother Hazera Begum and mmiv brothers whose blessing, inspiration. sacrjflce, and moral support opened the gate and paved to way
of
my higher study.1 want to say thanks to my senior Mominul Hague Rabin, student
of
Sher-e-Bangla Agricultural University, my classnates and fri/ow friends for their active encouragement and inspiration.Special thanks goes to the Agro-Environmenta! Chemistry Laboratory for providing me a/i types
of
research support and its funding authority CP-3645, W-2, A/F (3), HEQEP, UGCB, WB.The Author
EFFECT OF FOLIAR FERTILIZATION OF POTASSIUM ON GROWTH, YIELD AND NUTRIENTS CONTENT OF BRRI dhan29 UNDER
DIFFERENT SALINITY
ABSTRACT
An experiment was conducted at the net house and the Laboratory of Agro-Environmental Chemistry lab of the Department of Agricultural Chemistry, Sher-e-[Iangla Agricultural University. Dhaka - 1207 during the Soro season (I)ecember-Junc) of the year 2014-15 to study the reclamation of salinity by potassium fertilization methods. The experiment was completed using 4 salinity levels (0.3.6 and 9 dS m4 ) and 5 potassium fertilization processes (Ko= no foliar application ofK , K.s = 0.5 mMK foliar application of K. K1 = 1 mMK foliar application of K, Ki.s = 1.5 mMK foliar application ofK, K2 = 2 mMK foliar application of K and 2/3 soil application oftotal Mo? fertilizer in all the treatments). BRRI dhan29 was used as variety. Salinity adversely affected all the growth and yield parameters of BRRI dhan29. Like most of the parameters, the highest 1000-grain weight (21.85 g) was recorded in 0 dS m 1, while highest grain yield (5.375 ton ha4 ) was recorded in control salinity treatment. The maximum grain yield (3.892 ton ha4) and straw yield (5.532 ton ha4 ) were recorded from Ko.s and K0 respectively whereas the minimum grain yield (3.357 ton ha4 ) and straw yield (4.566 ton ha') were found from Ki.s and Kiotreatnient respectively. Use of potassium alleviated the adverse effects of high salinity on rice plant. Most of the growth and yield attributes varied significantly due to the different fertilization processes of potassium. Among them 0.5 mMK. 1.5 mMK and 2.0 mMk foliar spray, 2/3 rd soil application of total Mo? fertilizer gave better perthrmances with the salinity levels of 3, 6. and 9 dS m'. S0K05 gave the highest grain yield (6.187 ton ha4 ) while ScK1 .s gave the lowest grain yield (1.157 ton haS') .Na content in straw and grain increased with the increase in the salinity level while K content decreased. In this case also, foliar spray along with soil application of Mo?
fertilizer performed better while treated with salinity compared to sole foliar spray or soil applications.
CONTENTS
PACE NO.
I-Il UI
hr-v vi vu-vu'
Ix
1-4 5-19 6-12 12-19 20-26 20 20 21 2!
22 22 22 23 23 23 23 24-25 25-26 26
CHAPTER TITLE
ACKNOWLEDGEMENT ABSTRACT
LIST OF CONTENTS LIST OF TABLES LIST OF FIGURES
LIST OF ABBREVIATIONS
CHAPTER 1 INTRODUCTION
CHAPTER 2 REVIEW OF LITERATURE
2.1 Effect of Salinity 2.2 Effect of Potassium
CHAPTER 3 MATERIALS AND METHODS
3.1 Experimental site 3.2 Description of soil
3.3 Description of the rice variety 3.4 Layout of the experiment
3.5 Treatments
3.6 Sterilization of seed 3.7 Collection of pots
3.8 Sowing of seeds in seed bed
3.9 Preparation of pots for transplanting rice seedlings 3.10 Intercultural operations
3.11 Harvesting 3.12 Collection of data 3.13 Chemical analysis 3.14 Statistical analysis
\y \.P '
CHAPTER TITLE PAGE NO.
CHAPTER 4
RESULTS AND DISCUSSION 27-664.1 Plant Height 27-31
4.2 Number of leaves hill' 31-34
4.3 Number of tillers hilV' 35-38
4.4 Number of effective tillers hill-' 3841
4.5 Number of ineffective tillers hill1 4143
4.6 Panicic length (cm) 4345
4.7 Number of tilled grain panicle' 4547
4.8 Number of unfilled grain paniele4 4849
4.9 1000- grain weight (g) 49-51
4.10 Grain yield ton ha1 51-54
4.11 Straw yield ton ha-1 55-56
4.12 Root yield ton haS' 5748
4.13 Potassium (K) content in grain and straw (%) 58-61 4.14 Sodium (Na) content in grain and straw (%) 61-64
4.15 Calcium (Ca) content in straw (%) 64-66
CHAPTER 5 SUMMARY
AND CONCLUSION 67-69CHAPTER 6
REFERENCES 70-82APPENDICES 83-93
LIST OF TABLES
TABLE Na TITLE PAGE
NO.
3.1 Initial characteristics of the soil of the experimental field 21 4.1 Combined effect of different fertilization methods of potassium 30
and salinity level on plant height at different stages of BRRI dhan29
4.2 Combined effect of different fertilization methods of potassium 34 and salinity level on different salinity level on plant height at
different stages of I3RRI dhan29
4.3 Combined effect of different fertilization methods of potassium 37 and salinity level on different salinity level on Number of Tiller
hill
S
' of I3RRI dhan294.4 Combined effect of different fertilization methods of potassium 40 and salinity level on different salinity level on Number of
effective tiller hilt', ineffective tiller hilt'. panicle length (em) of BRRI dhan29
4.5 Combined effect of different fertilization methods of potassium 47 and salinity level on no. of filled grain panicle4, no. of unfilled
grain panicle' 1000- grain weight of BRRI dhan29
4.6 Combined effect of different fertilization methods of potassium 54 and salinity level on different salinity level on Grain yield ton ha
".Straw yield ton ha
S
' and Root yield ton ha t of BRRI dhan294.7 Combined effect of different fertilization methods of potassium 61 and salinity level on different salinity level on Potassium content
in grain and straw (%)
4.8 Combined effect of different fertilization methods of potassium 64 and salinity level on different salinity level on Sodium content in
grain and straw (%)
4.9 Combined effect of different fertilization methods of potassium 66 and salinity level on different salinity level on Calcium (Ca)
content straw (%)
LIST OF FIGURES
FIGURE TITLE PAGE NO.
NO.
Effects of salinity on plant height at different stages of BRRI 28 dhan29
2 Effects of different fertilization methods of potassium on plant 29 height at different stages of BRRI dhan29.
3 Effects of salinity on number of leaves hill1 at different stages of 31 BRRI dhan29
4 Effects of different fertilization methods of potassium on leaves 32 hilt' at different stages of BRRI dhan29.
5 Effects of salinity on number of tillers hilt' at different stages of 35 BRRI dhan29
6 Effects of different fertilization methods of potassium on number 36 of tillers hill1 at different stages of BRRI dhan29
7 Effects of salinity on effective number of tillers hilt' of BRRI 38 dhan29
8 Effects of different fertilization methods ofpotassium on effective 39 number of tillers hill1 at different stages of BRRI dhan29
9 Effects of salinity on ineffective number of tillers hilt' at different 41 stages of BRRI dhan29
JO Effects of different fertilization methods of potassium on 42 ineffective number of tillers hill" of BRRI dhan29
II Effects of salinity on Panicle length (cm) of BRRI dhan29 43 12 Effects of different fertilization methods of potassium on Panicle 44
length (cm) of BRRI dhan29
13 Effects of salinity on tilled grain panicle" Of BRRI dhan29 45 14 Effects of different fertilization methods of potassium on filled 46
grain panicle" of BRRI dhan29
IS Effects of salinity on number of unfilled grain panicle" of BRRI 48 dhan29
(Con 4)
FIGURE TITLE PAGE NO.
NO.
16 Effects of different fertilization methods of potassium on unfilled 49 grain panicic' of BRRI dhan29
17 Effects of salinity on 1000- grain weight (g) of BRRI dhan29 50
IS 51
Effects of different fertilization methods of potassium on 1000- grain weight (g) of BRRI dhan29
19 Effects of salinity on grain yield ton ha'of BRRI dhan29 52 20 Effects of different fertilization methods of potassium on grain 53
yield ton ha' of BRRI dhan29
21 Effects of salinity on Straw yield ton ha' of BRRI dhan29 55 22 Effects of different fertilization methods of potassium on Straw 56
yield ton ha-' of BRRI dhan29
23 Effects of salinity on root yield ton ha' of BRRI dhan29 57 24 Effects of different fertilization methods of potassium on root yield 58
ton ha" of BRRI dhan29
25 Effects of salinity on potassium content in grain of BRRI dhan29 59 26 Effects of potassium on potassium content in grain of BRRI 60
dhan29
27 Effects of salinity on Sodium content in grain of BRRI dhan29 62 28 Effects of potassium on Sodium content in straw of BRRI dhan29 63 29 Effects of potassium on calcium (Ca) content in straw of BRRI 65
dhan29
LIST OF ABBREVIATIONS
ABBREVIATION FULL WORD
% = Percent
= Attherateof - Degree Celsius AEZ = Agro-Ecological Zone
BRRI Bangladesh Rice Research Institute
cm = Centimeter
CRD = Completely Randomized Design CuSO4.51420 = Green vitriol
CV% = Percentage of Coefficient of Variance
Cv = Cultivar(s)
DAT Days After Transplanting DMRT = Duncan's Multiple Range Test
dS/m Dcci Semens per meter
EC = Electrical Conductivity
e.g As for example
eta! and others
g Gram
i.e. = that is
K - Potassium
Kg = Kilogram
kg ha4 = kg per hcctare KCI = Potassium Chloride
LSD Least Significant Difference
in = Meter
MoP = Muriate of Potash
N Nitrogen
NaOH = Sodium Hydroxide
NS Not Significant
OM = Organic matter
P = Phosphorus
p11 Hydrogen ion concentration
S = Sulphur
SAU = Sher-e-Bangla Agricultural University ha" = Ton per hectare
TSP = Triple Super Phosphate
Zn = Zinc
CHAPTER 1 q INTRODUCTION
Rice (Oryza saliva L.) is the main source of food for more than 60% of the world's population. It is the second most important crop in the world after wheat, more than 90 per cent of which is produced in Asia. Rice is the staple food of about 135 million people of Bangladesh. About 75%
of the total cropped area and over 80% of the total irrigated area is planted to rice in Bangladesh (BRKB. 2017). This increasing rice production has been possible largely due to the adoption of modem rice varieties on around 66% of the rice land which contributes to about 73% of the country's total rice production (BRKB. 2017). Rice (Or),za saliva L.) is called the major food crops in the world, but is also considered extremely salt-sensitive (Maas and HoiThan. 1977). Salinity is a major threat to crop production in the southern and south-western part of Bangladesh, where it is developed due to frequent flood by sea water of the Bay of Bengal and on the other hand application of irrigation with saline waters. Out of 2.85 million heetares of the coastal and off- shorn areas in Bangladesh, about 0.833 million hectares are arabIc lands, which constitute about 52.8 percent of the net cultivable area in 13 districts (Karim a at. I 990).The majority of the saline area (0.65 million ha) exists in the districts of Satkhira, Khulna, Bagerhat. Barguna. Patuakhali, Pirojpur and Bhola on the western coast and a smaller portion (0.18 million ha) in the districts of Chittagong. Cox's Bazar, Noakhali. Lakshmipur. Feni and Chandpur. According to the report of the Soil Resource Development Institute (SRDI, 2010) of Bangladesh different land area of Bangladesh are affected by different saline level such as, about 0.203 million ha of land is very slightly (24 dSm4), 0.492 million ha is slightly (4-8 dSm'). 0.461 million ha is moderate (8-12 dS m')and 0.490 million ha is strong (>12 dSm-1) salt affected soils in southwestern part of the coastal area of Bangladesh. Among the environmental stresses soil salinity is a widespread environmental problem that has been found to affect over 77 million heetares or 5% of the arable land worldwide (Wang Cl aL, 2001; Athar and Ashraf 2009). Salinity adversely affects on the plant growth and productivity. The yield reduction due to salt stress may account for substantial reduction of the average yield of rice by more than 50% (Bray el at. 2000). The scarcity of good
insufficient and irrigation agriculture is largely dependent on ground water resource. The ground waters of these areas are generally saline and sodic. If these water is used for irrigation without proper management may reduce the irrigated soils as salt affected and consequently crop production may be reduced.
Salinity affect in soil or water is one of the major stresses, can severely limit crop production (Shannon. 1998). The deleterious effects of salinity on plant growth and yield are associated with l.low osmotic potential of soil solution (water stress), 2.nutritional imbalance, 3.specific ion effect, or 4.a combination of these factors (Marschner. 1995). All of these causes adverse pleiotropic effects on plant growth and development at physiological and biochemical levels and production (Munns, 2002).
(Maloo. 1993) said Salt seems to affect rice during pollination, decrease seed setting and grain yield. Finck (1977) suggested that deficiency both K and Ca elements might play a significant role in the plant growth depression in many saline soils. Reducing the uptake of sodium and chlorine into rice while maintaining potassium uptake would aid growth under saline condition (Koyanta ci al.. 2001). In saline soil generally has higher concentration of Na and Mg than K and Ca high ionic imbalance may impair the selectivity of root membranes. This may results in passive accumulation of Na in root and shoot. Addition of k to a saline culture solution and foliar fertilization soil has been found to increase the dry weight and K content of shoots with a corresponding decrease in Na uptake in rice. Rice is sensitive to salinity especially during early seedling growth and flowering (Yoshida, 1981). Therefore the maintenance of low Na/k ratio on the soil during these two critical stages may benefit the rice plants. The parameters such as yield, tiller number per plant and spikelet number per panicle, have proved most sensitive to salinity and are highly significantly correlated to final seed yield in rice cultivar under salt stress (Zeng and
Shannon. 2000).
Under saline condition the foliar application of potassium is an effective method of providing a steady flow of nutrients, in combination with some traditional types of root-uptake fertilizers like sodium and calcium, to achieve better control of nutrients. Foliar spray is widely used to supply specific nutrients to many crops growing under saline environment. (Salama etal., 1996; El-Flouly
& Abou El- Nour, 1998) stated that foliar application of nutrients is partially overcoming the negative effect of stress condition influencing root growth and absorption capacity. Foliar
fertilization of both macro and micronutrient is practiced whenever, nutrients uptake through the root system is restricted due to salt stress in this respect (El-Flouly & El-Sayad, 1997). The advantages of foliar spray compared to soil fertilization include: immediate response, convenience of combination spray and comparatively low cost. Potassium is essential to all plants and inmost terrestrial plants K is the major cationic inorganic nutrient and is also enhance several enzymes functions. Potassium acts to balance the change in the cytoplasm of the cell, where K is the dominant counter ion for the large excess of negative charge on proteins and nucleic acids (Yang et at. 2004). Potassium contributes more than Na, Cl - and glycinebetaine in osmotic adjustment under saline conditions and activates the crucial enzymatic reactions such as formation of pyruvate. (Ashraf and Sarwar, 2002) stated that it is also a substantial contribution to osmotic pressure of the vacuole and thereby maintains cell turgor. Many factors determine the fertilizer efficiency for rice crop during cultivation such as soil, cultivar, season, environment, planting time, water management, weed control, source, form, rate, cropping pattern, time of application and method of application (De Dana. 1978).1'he feasible alternative may increase the cultivated areas by bringing salt affected soils under cultivation with high yielding varieties of rice by foliar application of potassium. Recently foliar application of nutrients has become an important practice in the production of crops while application of fertilizers to the soil remains the basic method of feeding the majority of the crop plants. But as far as the literature reviewed there are very few research works done on the effect of foliar application of Potassium fertilizer on the production of rice in salinity affected areas of Bangladesh. In this aspect, the present study therefore was undertaken to see the effect of foliar spray of potassium on BRRI dhan29 under saline condition.
In Bangladesh, limited information is available on the effect of foliar application of Potassium on growth, yield and nutrient contents of BRRI dhan29 under different saline condition. Therefore, present research work was conducted with the following objectives:
I. To study the effect of different levels of salinity on growth, yield and nutrients content of BRRI dhan29.
To find out the optimum dose of foliar application of Potassium for maximum growth.
yield and nutrient content of BRRI dhan29 under different levels of salinity stressed condition.
To evaluate the amount of Na, K, Ca in rice grain and straw.
CHAPTER 2
REVIEW OF LITERATURE
Rice is the staple food in many parts of the world. It is the main source of calories for almost 40%
of the world population (Haffman, 1991). Rice cultivars are classified on the basis morphology primarily into three types-indica,japonica, and javanica (Purseglove, 1985). Indica rice eultivars are generally adapted to areas with a tropical monsoon climate in the world. The rice cultivar are grown in Bangladesh belongs to the sub-spices indica (AIim, 1982). It is the second most important crop in the world after wheat, more than 90 per cent of rice is grown in Asia. In 2014-15, the production of rice is about 494.9 million tons (FAO, 2015). Rice is one of the most widely grown crops in coastal areas inundated with sea water during high tidal period, although it is usually considered moderately susceptible to salinity (Akbar ci aL. 1972; Korbe and Abdel-Aal, 1974;
Mori and Kinoshita 1987). Rice (Ora saliva L.) is rated as one of the major food crops in the world, but is also considered extremely salt-sensitive (Maas and Hoffman, 1977). It provides about 22 per cent of the world's supply of calories and 17% of the proteins.
It is sensitive to various environmental factors such as variety, soil, nutrient availability, temperature, humidity, light intensity and moisture for proper growth and yield. Many researchers have been studied on various aspects of rice in different countries. It is now realized that agriculture does not only refer to crop productions but also to various other factors that are responsible for crop production. The available literatures related to the present study are reviewed here.
Salinity is one of the most cricial environmental factors limiting the productivity of crop plants because most of the crop plants are sensitive to salinity caused by high concentrations of salts in the soil. A considerable amount of land in the world is affected by salinity which is increasing day by day. More than 45 million hectares (M ha) of irrigated land which account to 20% of total land have been damaged by salt worldwide and 1.5 M ha are taken out of production each year due to high salinity levels in the soil (Pitman and LAiuchli. 2002; Munns and Tester, 2008). On the other hand, increased salinity of agricultural land is expected to have destructive global effects, resulting in up to 500/0 loss of cultivable lands by the middle of the twenty- first century (Mahajan and Tuteja,
2.1 Effects of salinity
in most of the cases, the negative effects of salinity have been attributed to increase in Na and Cl - ions in different plants hence these ions produce the critical conditions for plant survival by intercepting different plant mechanisms. Although both W and Cl- are the major ions produce many physiological disorders in plant. Cl- is the most dangerous (Tavakkoli cial.. 2010). Salinity at higher levels causes both hyperionic and hyperosmotic stress and can lead to plant demise. The outcome of these effects may cause membrane damage, nutrient imbalance, altered levels of growth regulators, enzymatic inhibition and metabolic dysfunction, including photosynthesis which ultimately leading to plant death.
(Mahajan and Tuteja, 2005: Hasanuzzaman ci al.. 2012). Changing level of salinity of southwest coastal region of Bangladesh, crop Most of Bangladesh's coastal region lies on the southwest coastal region of the country. Approximately 30% of the crops land of Bangladesh is located in this region (Mondal ci al.. 2001) and continuous to support crops productivity and GDP growth.
But in the recent past, the contribution of crops to GD? has been decreased because of salinity. In total, 52.8% of the cultivable land in the coastal region of Bangladesh was affected by salinity in 1990 (Karim et(i!.. 1990) and the salt affected area has increased by 14600 ha per year (SRDI, 2001). SRDI had made a comparative study of the salt affected area between 1973 to 2009 and showed that about 0.223 million ha (26.7%) of new land has been affected by varying degrees of salinity during the last four decades and that has badly hampered the agro-biodiversity (SRDI, 2010). Farmers mostly cultivate low yielding, traditional rice varieties. Most of the land kept fallow in the summer or pre-monsoon hot season (March-early June) and autumn or post-monsoon season (October- February) because of soil salinity, lack of god quality irrigation water and late draining condition. In the recent past, with the production becomes very risky and crop yields, cropping intensity, production levels of crop and people's quality of livelihood are much lower than that in the other pans of the country. Cropping intensity in saline area of Bangladesh is relatively low, mostly 170% ranging from 62% in Chittagong coastal region to 114% in Patuakhali coastal region (FAO. 2007).
A high concentration of Na' and/or Cl- accumulation in chloroplasts is also inhibited photosynthesis. As photosynthetic electron transport is relatively insensitive to salts, either carbon metabolism or photophosphorylation may be affected due to salt stress (Sudhir and Murthy. 2004).
In fact, the effect of salinity on photosynthetic rate depends on salt concentration as well as plant species or genotypes.
Fageria (2003) evaluated the dry matter production and the concentration of nutrients in rice (Or)ca saliva L.) varieties from soil adjusted to different levels of salinity under a greenhouse conditions. Soil salinity levels were produced by applying 0.34 mol U' solution of NaCl which resulted in the following levels, control (0.29). 5. 10 and 15 dS nf conductivity of saturation extract. The effect of salinity on dry matter production varied from cultivar to cultivar. The concentration of P and K in the tops of rice cultivars decreased with increasing soil salinity. But the concentrations of Na, Zn. Cu and Mn increased.
Cha-um a ci (2005) conducted an investigation with an objective to evaluate the effective salt- tolerance defense mechanisms in aromatic rice varieties. Pathumthani I (FF1). jasmine (KDMLI05), and l-Iomjan (HJ) aromatic rice varieties were chosen as plant materials. Rice seedlings photoautotrophically grown in-vitro were treated with 0, 85, 171, 256, 342, and 427mM NaCl in the media. Data including sodium ion (Na*) and potassium ion (K) accumulation, osmolarity, chlorophyll pigment concentration, and the fresh and dry weights of seedlings were collected after salt treatment for 5 days. Na in salt stressed seedlings gradually accumulated, while K decreased, especially in the 342427 Mm NaCl salt treatments. The Na accumulation in both salt stressed root and leaf tissues was positively related to osmolarity, leading to chlorophyll degradation. In the case of the different rice cultivars. the results showed that the Hi variety was identified as being salt-tolerant, maintaining root and shoot osmolarities as well as pigment stabilization when exposed to salt stress or N? enrichment in the cells. On the other hand, PTI and KDMLI05 varieties were classified as salt-sensitive, determined by chlorophyll degradation using Hierarchical cluster analysis. In conclusion, the Hi-salt tolerant variety should be further utilized as a parental lion or genetic resource in breeding programs because of the osmoregulation defensive response to salt-salt-stress.
Hakim ciaL (2010) studied the response of twelve rice varieties against six salinity levels (0,4, 8, 12, 16 and 20 dS m') at germination and early seedling stages and found that salinity decreased the final germination per cent and led to reduction in shoot and root length and dry weight in all varieties. Further the), noticed that magnitude of reduction increased with increasing salinity stress.
Girdhar (1988) observed that salinity delayed germination, but did not affect the final germination
condition, the Na concentration in the cytoplasm of plant cells is low in comparitipn to the K content, frequently 10.2 versus 10 and even in conditions of toxicity, most of the cellular Na+
content is confined into the vacuoles (Apse ci at.. 1999).
Fisarakis ci aL (2001) reported a positive growth inhibition caused by salinity associated with a marked inhibition of photosynthesis. There is evidence that at low salt concentration salinity
sometimes stimulate photosynthesis.
Anbumalarmathi and Preeti (2013) reported that the response of eight indica rice varieties against six salinity levels (0, 4, 8, 12, 16 and 20 dS rn') was studied at germination and early seedling growth stage. Germination was completely arrested in six varieties at 20 dS m' salt concentration.
Rice varieties ADT43. 1R50. and MDU5 showed greater salt toleran BRRI dhan47 and Binadhan- 10 were treated with five concentrations of NaCl, viz., 0, 4, 8, 12. and 16 dSm'. Result indicated that plant height, number of effective tiller hill1, number of in effective tiller hilt', number of field grain panicle". number of unfilled grain panicle1, panicle length and grain yield hilt' were influenced at different levels of salinity. The number of effective tiller hill", panicle length, number of filled grain panicle-1 and grain yield hilt' were significantly decreased with the increased levels of salinity. It was found that the K content in shoot was decreased with the increased levels of salinity. The highest K content (1.77%) in shoot was found in Binadhan- 10 at 0 dSm". The highest Na content (1.69 %) in shoot was found in BRRI dhan47 at 12 dSm".
Between these two varieties Binadhan-lO showed better performance at salinity stress up to a certain level except plant height (Sultana ci at, 2014)
Hasanuzzaman ci at (2009) studied a significant reduction in germination rate of 4 rice cultivars when exposed to various concentration of salt (30-150mM). However, the sensitive cultivars were more prone to germination reduction under salt stress. In Vigna radiata, germination percentage decreased up to 55% when irrigated with 250 mM NaCl (Nahar and Hasanun'.aman, 2009). In a recent study. Khodarahmpour ci at (2012) conductcd drastic reduction in germination rate (32%), length of radicle (80%) and plumule (78%), seedling length (78%) and seed vigour (95%) when Zea mays seeds were exposed to 240mM NaCl.
Dolatabadian ci at (2011) observed that salinity stress significantly decreased shoot and root weight. total biomass, plant height and leaf number but not affected leaf area while studying with Glycine max.
s41ç\
For instance, in B. parv7ora, Panda ci at (2004) studied that rate of photosynthesis increased at low salinity while decreased at high salinity, whereas stomatal conductance remained unchanged at low salinity and decreased at high salinity.
In 0. saliva leaves, the reduction of ChI a and b contents of leaves were observed after NaCl treatment (200mM NaCl, 14 d) where reduction of the Chi b content of leaves (4 1%) was affected more than the ChI a content (33%) (Amirjani. 2011). In another study. 0. saliva exposed to 100 mM NaCl showed 30. 45 and 36% reduction in ChI a, ChI b and earotenoids (Car) contents compared to control (Chutipaijit ci at. 2011) which retarded the growth efficiency.
The available literature showed the effects of salinity on the seed germination of various crops like Oryra saliva (Xu ci at, 2031), Trilicum aestivurn (Akbarimoghaddani ci at, 2011), Zea 'nays (Carpici ci at, 2009; Khodarahampour etal.. 2012), Brassica spp. (Ibrar ci at. 2003; Ulfat ci at, 2007) and !-lelianthus annuus (Mutlu and Bozcuk, 2007). It is well established that salt stress has negative correlation with seed germination and vigor (Rehman ci at. 2000). Higher level of salt stress prevents the germination of seeds while lower level of salinity induces a state of dormancy (Khan and Weber, 2008).
According to Romero-Aranda ci at (2006) increase of salt in the root medium can lead to a decrease in leaf water potential and, hence, may affect many plant processes. Osmotic effects of salt on plants are the result of decreasing of the soil water potential due to increase in solute concentration in the root zone. At very low soil water potentials. this condition interferes with plants' ability to extract water from the soil and maintain turgor. However, at low or moderate salt concentration (higher soil water potential). plants adjust osmotically (accumulate solutes) and maintain a potential gradient for the influx of water. Salt treatment caused a significant reduction in relative water content (RWC) in sugar beet varieties (Ohoulam ci at. 2002).
In 0. sativa varieties, grain yield, which is the ultimate product of yield components greatly influenced by salinity levels in soil water
Rice is relatively tolerant during germination, becomes very sensitive during early seedling stage, gains tolerance during active tillering. but becomes sensitive during panicle initiation, anthesis and fertilization and finally relatively more tolerant at maturity (Makihara ci at, 1999 and Singh ci at, 2004).
Studies have shown that a very poor correlation exists between tolerances at seedling stage with that during reproduction, suggesting that tolerance at these two stages are regulated by a different set of genes (Moradi et al., 2003)
The reproductive stage is crucial as it ultimately determines the grain yield. However, the importance of the seedling stage cannot be undermined as it affects crop establishment. Salinity reduces the growth of plant through osmotic effects, reduces the ability of plants to take up water and this causes reduction in growth. There may be salt specific effects. If excessive amount of salt enters the plant. the concentration of salt will eventually rise to a toxic level in older transpiring leaves causing premature senescence and reduces the photosynthetic leaf area of a plant to a level that cannot sustain growth (Munns. 2002).
Plant roots experience the salt stress when Na and Cl along with other cations are present in the soils in varying concentration (Ito ISO mM for glycophytes and more for halophytes). The toxic ions sneak into the plant along with the water stream which moves from soil to the vascular system of the root by different pathways like symplastic and apoplastic. NC and K are mediated by different transporters which are clearly demonstrated by Garciadebleas et at (2003). Dry weight of root, shoot and yield significantly reduced with the increase of salinity levels, while MR232 and MR2I I were less aflbcted. Na ions accumulations increased in the root and shoot with the increase of salinity, while the lowest accumulation was in MR2I I. Na'/ K ratio sharply increased in the root with increasing the salinity. Whereas. Ca1 /Na and Mg/Cafl ratio showed decreasing trend with increasing salinity level. The maximum amount of nitrogen and phosphorous accumulation was observed in the shoot of MR2II, while Na' in BRRI dhan29. IC in Pokkali.
The highest accumulation of Na and K observed in the root of MR2 19. The maximum CC and Mgt were found in MR33 and MR2I I. respectively. Considering all, genotypes MR2I I andMR232 were found to be relatively tolerant to salt than the other genotypes (Hakim et at.
2014).
Alam et al. (2001) at the reproductive stage, salinity depressed the yield of grain much more than at the vegetative growth stage. These authors maintained that at critical salinity level straw yield was normal but produced little or no grain. The decrease in the yield of grain was found proportional to the salt concentration and the duration of the saline treatment.
Alani et at (2004) attributed the possible reasons for decrease in the shoot and root growth in salinized plants as reduction of photosynthesis, which in turn limits the supply of carbohydrates
needed for growth and reduction of Rice cultivars differ substantially in their growth rate with the most vigorous lines being the traditional varieties. Naturally occurring salt resistant varieties invariably belong to these traditional tall varieties. The high vigour of land races may enable them to tolerate growth reduction. Vigorous growth also has a dilution effect. The Na' uptake of the salt tolerant land race 'Pokkali' is not less than the salt sensitive dwarf IR-28 but the low Na' concentration in Pokkali is attributed to the diluting effect of its rapid vegetative growth (Yeo ci (iI,1990 and Bohra and Doerffling. 1993).
Dubey and Sharma (1989) studied that delayed differentiation of root and shoot and reduction in seedling vigour index with increase in salt concentration.
In case of variety BRl I. more than 30 per cent reduction of effective tillers was observed at 150 mM NaCl treatment compared to control.
Aref(20 13) studied on the effect of different growth stages on all yield components except number of tillers was significant. Different growth stages showed different sensitivity to salinity. In fact, the primitive growth stages, that is, tillering and panicle initiation showed more sensitivity to salinity than final growth stages (panicle emergence and ripening). Therefore, irrigation with saline water at the early growth stages has more negative effect on yield and its components.
l3aba and Fujiyama (2003) investigated short-term (72 h) responses of the water and nutritional status to Na-salinization in rice (Oryza saliva L. cv. Koshihikair) and tomato (Lvcopersicon esculeniwn Mill cv. Sawn) using pot experiments. The short-term effect of supplemental K and Ca to the nutrient solution on the water status and absorption and transport of ions in the plants was also investigated. In both species. Na salinity resulted in the deterioration of the water status of tops and in nutritional imbalance. However, in rice, it was possible to decrease the deterioration of the nutrient status by enhancing the transport of cations. especially K. while tomato could maintain an adequate water status by inhibiting the water loss associated with transpiration. On the other hand, the water status in rice and the nutritional status in tomato markedly deteriorated by high Na lcvel in the solution. Supplement K and Ca could not ameliorate the water status in both species, and even worsened the status in rice. In rice, a close relationship was observed that between the osmotic potential (OP) of the solution, water uptake and water content. The water status of rice, therefore, seemed to depend on OP of the solution. Supplemental K and Ca, on the other hand, were effective in the amelioration of the nutritional status. In tomato, supplemental Ca could improve the nutritional balance by suppressing the transport of Na and enhancing that of the
other cations in avoidably the deterioration of the water status. Thus, the differences in the responses of the water and nutritional status of rice and tomato to high Na salinizaiion and to supplemental K and Ca were evident in a short-term study and supported a similar tendency observed in a long-term study.
2.2 Effects of potassium (K)
Foliar application is one of the methods of fertilizer application. Foliar application refers to the spraying on leaves of growing plants with suitable solutions. It is effective to the crops which are growing on water-logged condition. Plant may absorb fertilizers e.g.; urea directly when applied to their foliage as aqueous solution. This method can be used for any plant nutrient, but commonly employed in case of micronutrients which are in relatively smaller amount.
In many cases aerial spray of nutrients is preferred and gives quicker and better results than the soil application (Jamal ci at 2006). Recently foliar of nutrients has become an important practice in the production of crops while application of fertilizers to the soil remains the basic method of feeding the majority of the crop plants.
The highest values for K recovery (72.87%) and agronomic efficiency (13.12) were observed when K was applied as K2SO4 followed by KNOj and KCI. Potassium recovery and agronomic efficiency
followed the same order as that of K uptake. i.e.. K2SO4 > KNO3> KCI (Uexkull von. 1978).
Approximately 7 and 11% lower paddy yield (as compared to obtained with K2SO4) produced with KNO3 and KCI application respectively might be due to the reason that generally high concentration of NO3 ions absorption by leaves directly increases acidity which could cause stomatal disturbance as well as firing of leaves and as excessive Cl ions are related to toxicity in growing plants through active absorption across the cytoplasm membrane. Hence, it is quite possible that K sources containing NO3 and Cl resulted comparatively less growth and yield (Matsuda and Riaz, 1981; Glass and Siddiqui. 1984 and Ramos ci at 1999).
Ashraf et a?. (2010) studied a hydroponics experiment to evaluate the role of potassium (k) and silicon (Si) in mitigating the deleterious effects of NaCl on rice cultivars differing in salt tolerance. Two salt —sensitive (CPE243 and SPE 213) and two salt-tolerant (HSF 240 and CP 77- 400) rice varities were grown for six weeks in Vi strength Johson nutrient solution. The nutrient solution was Salinized by two NaCl levels o and lOOmmoL NaCI) and supplied with two levels of
K (0 and 3 mmoL)and Si (0 and 2mmoL). Applied NaCl enhanced Na* concentration in plant tissues and significantly (P C 0.05) reduced shoot and root dry matter in four rice cultivars.
However magnitude of reduction was much greater in salt-sensitive cultivars than salt-tolerant cultivars. The salts interfered with the absorption of Kt and Ca2 and significantly (PC 0.05) decreased their uptake in rice cultivars. Additional of K and Si either alone or in combination significantly (P<0.05) inhibited the uptake and transport of Na7 form roots to shoots and improved dry matter yields under NaCl conditions. Potassium uptake K'/Na' ratios, and Ca24 and Si uptake were also significantly (pc0.05) increased by the additional of K and or / Si to the root medium.
In this study. K and Si enhanced salt tolerance in rice cultivars was ascribed to decreased Na connection and increased K with a resultant in K'fNa+ ratio, which is a good indicator to assess plant tolerance to salt stress.
Mocini et aL (2006) conducted a 3-year trial from 1999 to 2001 in Karaj, Iran. Treatments included urea application in two methods (foliar application and top dressing). The results indicated that foliar application of urea had a significant effect on yield.
Pot experiments were conducted by Andrecvska ci at (2003) to determine the effect of nitrogen fertilizers on the dry matter yield and the total nitrogen content in the roots, stems, leaves and panicles of rice. The complex fertilizer was applied as a basic treatment while the nitrogen fertilizer was applied as a double foliar split application at the start of the heading stage. The result reported that the method and the time of nitrogen application resulted a significant positive effect on the yield increase of row and dry matter of roots and aboveground parts and on their total nitrogen content.
Horjin and Emam (2001) conducted a field experiment in Shiraz. Iran during 1998-99 to study the effect of rate and time of foliar urea application on protein content and quality in two cultivars of winter wheat, 'Falat' and 'Marvdasht'. Five urea foliar application rates (0. 8. 16, 24 and 32 kg N per ha) and three stages of application (booting, anthesis and milk stage) were evaluated. The results showed that each 8 kg per ha increment in N applied urea was associated with a 0.6%
increase in grain protein in both cultivars. Both grain yield and protein percentage increased, resulting in higher protein yield.
Duraisami ci aL (2002) had conducted field experiments during the winter of 1991-95 and 1996-
application of 100% recommended NPK rate (Ti), Ti+ 20% additional N(12), 50% recommended N + 100% recommended P and K rates + 2.5% urea foliar spray at the active tillering and panicle initiation stages (Ts). 100% P and K rates +2.5% urea foliar spray at active tillering, panicle initiation, mid-heading, first flowering and 50% flowering stages (T4). Ti ± 2 kg phmphor bacterium per ha (l's). kg ZnSO4 (16), Ii + 2% urea foliar spray at active tillering and panicle initiation stages (1'7 and Ti -F 1% o ZnSO4 spraying at active tillering and panicle initiation stages (T8). 12 resulted in the tallest plant (101.9cm) and highest number of productive tillers (10), grain yield (6713 kg ha") and straw yield (918 kg ha"), whereas 13. T4 and Ti gave the highest chaff per panicle (12.4) harvest index (43.64%) and number of grains per panicle, respectively.
Badole and Narkhede (2000) conducted a field experiment in Maharashtra, India during 1995-98 to study the effect of foliar spray of 2% urea for 6 times at tO days intervals (27.5 kg N ha") and 3 times at the stages of tillering, panicle initiation and grain-filling, with and without basal application of NPK of transplanted rice (O'yza saliva cv. Sye-75). The growth and yield of rice increased significantly with the application of 50. 50 and 50 kg ha" (N: P: K) as a basal rate and foliar application of urea at the 3 growth stages. This same treatment showed the highest values for the yield attributing characters, nitrogen uptake, grain and straw yields (mean of 35.15 and 38.45 q ha" respectively) and the highest net profit of Rs 3546. It also recorded up to 50 kg ha-I.
and showed the best utilization of applied N. In contrast, treatment with the recommended fertilizer rate (100,50 and 50 kg ha-1 (N:P:K) resulted a net profit of only Rs 1566.
Bohra and Doerffling (1993) grew a salt-tolerant (Pokkali) and a salt-sensitive (11128) Variety of rice (Orwa saliva) in a phytotron to investigate the cfrcct of K ( 0,25.50 and 75 mg K kg"= soil application on their salt tolerance. Potassium application significantly increased potential photosynthetic activity (Rfd value), percentage of filled spikelets. yield and K concentration in straw. At the same time, it also significantly reduced Na and Mg concentrations and consequently improved the KINa, KIMg and KJCa ratios. lR28 responded better to K application than Pokkali.
Split application of K failed to exert any beneficial effect over basal application.
Din etal. (2001) used artificially salinized soils to see the effect of foliar and soil application of K on rice. Results showed that the number of tillers planu'and paddy and straw yield and grains to straw ratio significantly reduced with the increase in salinity. All K application methods increased the above parameters significantly at all salinity levels over distilled water spray.
Foliar application of KNO3 at 0.50% increased the seed yield by 85.7% over the unsprayed control in pooled data owing to the favorable effect on yield attributes. Spray of KNO3 at 0.50% during flowering supplied N and K which are effectively absorbed as anion and cation by plants. and might have delayed the synthesis of abscisic acid and promoted cytokinin activity, causing higher chlorophyll retention (Mengal. 1976).
Increasing levels of salinity decreased K concentration in shoots and straw, which was increased significantly by foliar and soil application. The K/Na ratio decreased significantly by the increase of salinity, while this ratio increased significantly by the foliar and soil application of K.
Dinet at (2001) conducted a pot experiment at salinity levels of 1.6,6.0 and 12 dSm' with 50mg kg' K2SO4 as soil application and 0.5% K2SO4 solution as foliar spray on rice. He concluded that foliar and soil application of K increased significantly the number of tillers plan&, plant height, number of grains plant, paddy and straw yield and grain to straw ratio in saline conditions. He also found that with foliar and soil application of K increased significantly the number of tillers plant', plant height, number of grains plant', paddy and straw yield and grain to straw ratio in saline conditions. He also found that with foliar and soil application of potassium, the concentration of N and P increased in rice shoot and straw in saline conditions. He also found that foliar application of K increased the Kt concentration in rice shoot and straw compared to soil application.
.Mehdi etal. (2007) conducted a field experiment to evaluate the response of rice crop to potassium fertilization in saline-sodic soil during 2005. In this experiment five rates of K:O (0, 25, 50. 75 and IOU kg ha
S
') were applied in the presence of basal doses of N and P20s i.e.I 10 and 90kg ha1 respectively. The results showed that increasing rates of potassium fertilizer increased the number of tillers m 2, plant height (cm), 1000-paddy weight and paddy as well as straw yield significantly.With increasing rates of potassium fertilizer, concentration of potassium in paddy and straw increased significantly. It was concluded from the results that there was an increase of 30.65% in paddy over control by applying potassium (tOO kg K20 ha4) in saline-sodic soil.
Ion homeostasis in cell is taken care of by the ion pumps like antiporters, symporters and carrier proteins on membranes (plasma membrane or tonoplast membrane). Salt Overly Sensitive (SOS) regulatory pathway is one good example of ion homeostasis. This pathway is activated after the
receptor perceives the salt stress to alter protein activity and gene transcription by signaling intermcdiatc compounds. Guo cial. 2004)
Addition of salt induces the NC/H antiporter activity but it increases more in salt tolerant than salt sensitive species (Staal
a
at. 1991).Na which enters leaf cells is pumped into vacuole before it reaches to toxic level for enzymatic activities. This pumping activity is controlled by valuolar NaIH' antiporters (Blumwald ci aL.
2000)
Shereen ci at (2005) and Haq
a
al. (2009) screened seven rice cultivars at 100 mM of salt concentration and reported that with increase in salinity, a significant reduction was observed in shoot dry weight: shoot fresh weight and number of tillers plant' after 42 days of salt stress.The researchers Awala
a
at (2010) screened 54 genotypes of Oryza glaberruna. NERICA (21) and 0. cat/va (41) and grown in pots by irrigating with NaCl (80 mM) solution. They observed that relative root biomass was significantly lower in O'yza g!aherrima than others.Lee a at (2003) observed significantly tower reduction of all growth parameters of tolerant (nd/ca varieties than japan/ca varieties. They further observed that tolerant md/ca cultivars were good Na' excluders with high K absorption and maintained a low Nail K ratio in shoot and indicated that tolerance level of md/ca was higher than that ofjaponica. They also observed that the cultivar with low Na/ K ratio was highly tolerant and the susceptible one had high Na/ K ratio.
Ali ci at (2004) experimented significant reduction of yield in many rice genotypes at a salinity level of 8.5 dS nf' besides the reduction of many yield contributing parameters vi:., chlorophyll content, productive tillers plant', and panicle length and fertility percentage
Uddin ci at (2007) stated that salinity reduced the number of effective tillers planr', number of grains panicle'. 100-grain weight and yield plant' of rice. Hasanuzzaman ci al. (2009) reported that 1000-grain weight and grain yield decreased with increase in levels of salinity in rice.
Govindaraju and Balakrishnan (2002) indicated that plant height, number of productive tillers hillS ', 1000-grain weight. grain yield, straw yield, chlorophyll content and photosynthetic ability of rice decreased with increase of salinity.
Khatiin et at (1995) reported that salinity delayed flowering, reduced the productive tillers plant fertile florets panicle', seed set (weight grain-'), 1000-seed weight and overall grain yield Khatun ci al. (1995).
Zayed et al. (2007) conducted two field experiments at the experimental farm of El Sirw Agriculture Research Dammiatta prefecture, Egypt during 2005 and 2006 seasons. The study aimed to investigate the effect of various potassium rates; Zero, 24,48 and 72 Kg K20 ha'. on growth. sodium, potassium leafcontent and their ratio at heading, grain yield and yield components of three hybrids: SK2034H. SK2046H and SK2058H and three varieties; Giza 177, Giza 178 and Sakha 104. The economic values were also estimated. The experimental soil was clayey with salinity levels of 8.5 and 8.7 dS/m in the first and second seasons, respectively. The experiments were performed in a split plot design with four replications. The main plots were devoted to the tested rice varieties, while potassium rates were distributed in the sub plots. The studied varieties varied significantly in their growth parameters, NC and K leaf content at heading as well as ratio, yield components and their economic values. SK2034H surpassed the rest varieties without any significant differences with SK2046H. SK20581-1 didn't show advantage over Giza 178 or Sakha 104. Giza 177 was the worst under such conditions. Increasing potassium rate significantly improved all studied traits leading to high grain yield. Furthermore, potassium succeeded to reduce Nat lower Na /K ratio and raised K resulted in considerable salinity withstanding. The hybrids of SK2034H and SK2046H as well as the salt sensitive rice variety Giza 177 were the most responsive cultivars for potassium fertilizer up to 72 kg K20 Tha. Consequently, the economic estimates SK203411 had the higher net return and the high potassium level of 72 kg K20 ha" gave the highest values of economic parameters under the tested saline soil conditions.
Ebrahimi ci al. (2012) conducted a pot experiment to examine the effects of potassium application methods on the response of rice (Oiyza saliva L.) under different soil salinity levels. Four methods of potassium application: Ko: spraying with distilled water every 10 days interval (control); Ki:
the use of 65mg K Kg soil; K2: spraying 5% K2SO4 solution in every 10 days interval; K3: the use of 65mg K Kg" soil plus spraying with 5% K2SO4 solution every 10 days interval and four levels of irrigation water salinity (tap water and salinities 2, 4 and 6 dSm') were investigated.
Results showed that soil salinity affected growth and yield component parameters in most of the cases. Potassium application alleviated the stress condition and significantly improved dry matter yield and yield components in rice. Grain, straw, total biological yield, harvest index. 1000 grains weigh, root dry weigh and total tillers significantly were decreased with increasing salinity while
grain protein was increased with increasing salinity. The interaction between salinity levels and methods of potassium application was significant only for root dry weight.
Nelson (1978) believed that potassium has a positive role in plant growth under saline conditions, because this clement plays an essential role in photosynthesis and osmoregulatory adaptations of plant to water stress. Adequate potassium supply is also desirable for the efficient use of Fe while higher potassium application results to competition with Fe.
Saqib ci cii. (2000) studied a significant reduction in all growth parameters considered and an increased concentration of Na and Cl* , decreased concentration K and decreased Kt:Nat ratio.
Most of yield decreases caused by abiotic stresses result from salinity, drought, high or low temperature, inadequate mineral nutrient supply and soil acidity.
The K determination from plant samples, wet digestion method (nitric acid + perchloric acid in 2:
1 ratio) was followed and measured the concentration by flame photometer (Rhoades. 1982). The data regarding number of tillers per plant and biological yield at maturity were recorded. The application of K produced highest tillers, straw and paddy yield. The maximum concentration of K and K uptake in straw and paddy was recorded with K Similarly the highest values for K recovery and agronomic efficiencies were calculated with K. Therefore it can be concluded that the K is the best source of K for foliar spray to increase paddy yields (All et al. 2005).
Patra and Poi (1998) applied different forms of trace elements to rice cv. IET-5665 and IET-6141 in trace elements deficient soil at North Bengal (India). The maximum grain yield (2.39 t ha-I) was obtained with foliar application of 500g chelated Zn haS'. followed by foliar application of Zn + B + Mo mixture + organic manure (grain yield 2.36 t ha4) as basal dose showed as good as chelated zinc.
The comparatively higher paddy yield (about 20% over control) registered by K application might be due to perfect nutrition with adequate source of K application K that have resulted in vigor growth of crop and ultimately higher yield (Sarkar and Malik.2001).
Mohiti ci al. (2011) conducted an experiment with the aim of comparing the efficiency of potassium spraying and application in soil; and its effect on yield and yield components of rice
under salinity stress in a greenhouse experiment. Treatments included four levels of irrigation water salinity (tap water and salinities 2. 4 and 6 dS/m) and four methods of K application: a, spraying with distilled water as control; b, application of potassium on soil: c, potassium spraying and d, application of potassium on soil plus spraying. Every treatment was replicated three times and study was conducted as a complete randomized block design. The results show that grain yield and shoots, 100 seeds weight, tiller number, root dry weight and potassium uptake in seeds and shoot significantly decreased with increasing salinity. The best method of K application was soil intake plus spraying method.
CHAPTER 3
MATERIALS AND METHODS
This chapter presents a brief description about the materials and methods those were utilized when researching and writing this work. It describes the key methods, use of different parameters to correlate with establishing rice plant. It further covers the data collection procedure, source of data and ways of data were analyzed.
3.1 Experimental site
The experiment was conducted under pot-culture at the net house and the Laboratory of Agro- Environmental Chemistry lab of the Department of Agricultural Chemistry, Sher-e-Bangla Agricultural University. Dhaka-1207 during Boro rice cropping (December-june) 2014 -15 , to study the effect of foliar application of potassium on growth, yield and nutrient contents of BRRI dhan29 under different salinity levels.
3.2 Description of soil
The soil of the experiment was collected from the field of Sher-e-Bangla Agricultural University (SAU) Farm. The soil was Shallow Red Brown Terrace soil under Tejgaon series belonging to the Agro-Ecological Zone 28 (Modhupur Tract). The soils was clay loam in texture with common fine medium distinct dark yellowish brown mottles. The collected soil was pulverized and inert materials, visible insect pest and propagules were removed. The soil was dried in the sun, crushed carefully and thoroughly mixed. The initial physical and chemical characteristics of the soil are presented in Table 3.1.
Table 3.1 Initial characteristics of the soil of the experimental field Particle-size Sand
analysis of
soil Silt
C lay
30.55 37.29
32.16
Textural Class Clay loam
P11 6.3
Total N (%) 0.075
Organic matter (%) 0.80 Phosphorous (mg kg4) 16 Potassium (mg kg1) 15
Sulphur(mg kg4) 10
Zinc (mg kg1) 1.30
3.3 Description of the rice variety
BRRI dhan29 isa high yielding variety of rice which was, used as the test crop in this experiment.
This variety was released in 1994 by Bangladesh Rice Research Institute, Gazipur. Life cycle of this variety ranges from 150 to 160 days.
3.4 Layout of the experiment
The experiment was set in Completely Randomized Desi (CRD) having two factors with 3 replications.
The treatment combination of the experiment was assigned at random into 20 pots of each at 3 replications.
3.5 Treatments
Salinity treatments consisted of 4 levels (0. 3, 6 and 9) dS ni' designated as Sr 0 dSm', S = 3dSm 1, S66 dSm'. S9 =9 dSm 1 respectively. For 3 dS 5.76 g NaCI. for 6 dS 11.52 g NaCl, for 9 dSm' 17.28 g NaCl is taken in 3L of water in each pot. 5 levels of K (0, 0.5, 1.0, 1.5,2.0) mMK designated as KoOmMK, K2 =0.5 mMK, Ks = l.OmMk, 1(4=1.5 mMK. K 5 =2.OmMK.
Levels of salinity (4):
Levels of potassium (5):
S0 =OdS m4
= No Potassium is applied as foliar application. Ko
= 3 dS m4 Ko.s = 0.5 mM K applied as foliar application.
So=6dSni'
Sq = 9 dS m' K,.rI.0 mM K applied as foliar application.
K, s = 1.5 mM K applied as foliar application.
K2o 2.0mM K applied as foliar application.
All the treatments were applied in I day interval and in all treatments 2/3 rd of recommended dose of K (as MoP fertilizer) was applied in the soil.
3.6 Sterilization of seed
Prior to germination test seeds were surface sterilized with 1% sodium hypochiorite solution. The glass vials containing distilled water for seed rinsing was sterilized for 20 minutes in an auto dave at 121 ± 11C and at IS bar air pressure.
3.7 Collection of pots
The required number of plastic pots having 24cm top, 18cm bottom diameter and 22cm depth were collected from the local market and cleaned before use.
3.8 Sowing of seeds in seed bed
Previously collected seeds were soaked with water for 24 hours and then washed thoroughly in fresh water, and incubated for sprouting. Seeds were sown on the 9' December 2014 in the wet seed bed. Required amount of fertilizers were applied one day prior to sowing of seeds in the seed bed.
3.9 Preparation of pots for transplanting rice seedlings
Recommended doses of N, P and S (100 kg N from urea, 20kg p from TSP and 12 kg S from Gypsum respectively) ha' were applied. The whole amount of TSP. MOP, gypsum and 1/3rd of urea were applied prior to final preparation of the pots. According to treatment rate, the whole amount of supplemental K (as KNO3) was also added in the respective pots. There after the pots containing soil were moistened with water. Six weeks-old seedlings were transplanted on the 10 February 2015 in the respective pots. Two weeks after transplanting the salt solutions were applied in each pot according to the treatments. To avoid osmotic shock, the required amount (at the rate of 640 mg per litre distilled water for I dS mt) of salt solution was added in three equal installments at one week intervals until the expected conductivity was reached as described by Razzaque no! 2010. The salinity i.e. Electrical Conductivity (EC) of each pot was measured with a conductivity meter (Model-D1ST 4 MANNA HI 98304) and the necessary adjustments ofsalinity were made. The remaining 2/3 urea were top dressed at two equal divisions after 25 and 50 days of transplanting.
3.10 Intercultural operations
Weeds grown in the pots and visible insects were removed by hands when necessary in order to keep the pots neat and clean. The soil was loosening by hand during the period of experiment.
Watering was done in each pot to hold the soil water level and salt concentration constant when needed.
3.11 Harvesting
The crop was harvested at maturity on 15th May 2015. The harvested crop of each individual pot was bundled separately. Grain, straw and root yields were recorded as ton ha"
3.12 Collection of data
Data collections were done on the following parameters
I. Plant height (cm) Number of leaves hill"
Number of tillers hill"
Number of effective tillers hill"
Number of ineffective tillers hill"
Panicle length (cm)
Number of filled grains panicle"
8-Number of unfilled grains panicle"
9. 1000-grain weight (g) tO. Grain yield ton ha"
II. Straw yield ton ha"
Root yield ton ha-'
Chemical Analysis of rice grain and straw: Na, K and Ca.
Plant height (cm)
Plant height (cm) was measured from the root base to the tip of the longest leaf at the time of 35, 45, 75 and 90 DAT.
Number of leaves bill"
Number of leaves hill" of tagged plants was measured during the time of 35. 45, 75 and 90 DAT.
Stem and root dry weight (g)
Stem and root dry weights were measured after separating the shoots and roots of tagged plants following by oven-drying.
Number of effective tillers and panicles hill'
Number of Effective tillers and panicles hilt' were counted at maturity.
Number of grain panicle', filled grains panicle1, and unfilled grains panicle'.
In case of more than 5 effective tillers hilt', average number of grains panicle" was calculated by counting the number of filled grains and unfilled grains of 5 panicles hilt' which was selected randomly. In case of less than 5 effective tiller hilt', average number of filled grain was calculated by counting the number of filled grains and unfilled grains of all the panicles hilt'.
Dry weight of filled grain (g hill 4
Dry weight of filled grain (g hilt') was measured after oven-dried to 14% moisture condition.
Thousand grain weight (g)
Thousand grains weight hilt' was calculated by weighing 100 grains of each treatment and then multiplied by 10.
Grain yield hilt' (g)
- The grain yield of the hill which had effective tiller was recorded by weighing after proper drying the grain.
Chemical analysis
Rice plants were separated into roots and shoots after uprooting and rinsed repeatedly with tap water and finally with distilled water and then dried in an oven at 70°C to obtain constant weight.
Oven-dried shoot samples, root samples and grain samples were ground in a Wiley Hammer Mill.
samples of rice plant were taken in digestion tube. About 10 mL of concentrated pereloric acid in a digestion tube and left to stand for 20 minutes and then transferred to a digestion block and continued heating at 1000C. The temperature was increased to 3651C gradually to prevent frothing (500C steps) and left to digest until yellowish color of the solution turned to whitish color. Then the digestion tubes were removed from the heating source and allowed to cool to room temperature.
About 40 mL of de-ionised water was carefully added to the digestion tubes and the contents filtered through Whatman no.40 filter paper into a 100 ml. volumetric flask and the volume was made up to the mark with de-ionised water. The samples were stored at room temperature in clearly marked containers.
After digestion. approximately 10 ml.. of each digest samples was stored in a plastic bottle for determination of the Na', K' and Ca2 .Content of Na, K and Ca2 were determined by Flame Photometer. After that, the percent of Na, K. Ca values were also calculated from concentration of Na, K. Ca in the plant tissues.
3.14 Statistical analysis
The collected data were analyzed statistically following CRD design by MSTAT-C computer package programme developed by Russel (1986). The treatment means were compared by Least Significance Differences (LSD), Duncans Multiple Range Test (DMRT) and regression analysis were used as and where necessary.
CHAPTER 4
RESULTS AND DISCUSSION
An experiment was conducted during the Boro season of (December-june) 2014-2015 to evaluate the response of BRRI dhan29 to potassium supplementation as foliar application at different salinity levels. It was conducted in the net house of Agro-Environmental Chemistry Laboratory of the Department of Agricultural Chemistry and in the Laboratory of Agro-Environmental Chemistry of Sher-e-Bangla Agricultural University (SAU), Dhaka. The different growth and yield parameters were studied including plant height, number of leaves hill', grain, straw and root yield in ton ha", number of effective tiller hill", panicle length, number of filled and unfilled grain hill '.weight of filled grain in ton ha". thousand grain weight (g) and Na, K and Ca content in grain ,straw and of the selected rice cultivar (BRRI dhan29) .The results are presented in figures and tables in this chapter and their possible interpretations are done as follows-
4.1 Plant Height Effects of salinity
The plant heigh
