05-01613 A - SAU Institutional Repository

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TILLERING, DRY MAflER ACCUMULATION AND PRODUCTIVITY OF HYBRID RICE IN AMAN SEASON

r us'

JUBAYER-AL-MAHMUD Registration No.: 05-01613

A thesis

submitted to the Faculty ofAgriculture, Sher-e-Bangla Ar/cultural University, Dhaka.

in partial fulfilment of the requirements for the degree of

MASTER OF SCIENCE IN

AGRICULTURAL BOTANY

SEMESTER: JULY-DECEMBER, 2010

V

Approved by:

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^reb^Supervisor (Md. Moinul Haque) Associate professor

Co-supervisor

Asim Kumar Rhadra Chairman

Examination Committee là

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This is to certifr that the thesis entitled, "TILLERING, DRY MATTER ACCUMULATION AND PRODUCTIVITY OF HYBRID RICE IN AMAN SEASON" submitted to the Faculty of Agriculture, Sher-e- Bangla Agricultural University. Dhaka, in the partial fblfilment of the requirements for the degree of MASTER OF SCIENCE IN AGRICULTURAL BOTANY, embodies the result of a piece of

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JIde research work carried out by JUBAYER-AL-MAHMUD,

Registration No. 05-01613 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.

Dated: (Prof. 4.M"Mshamsuzzaman)

Place: Dhaka, Bangladesh ltesearch Supervisor

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DEDICATED TO MY

BELOVED FATHER

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ACKNOWLEDGEMENTS

Alhamdulillak all praises are due to the almighty Allah Rabbul Al-Amin for his gracious kindness and infinite mercy in all the endeavors the author to let him succenfully complete the research work and the thesis leading to Master of

Science.

The author would like to express his heartfelt gratitude and most sincere appreciations to his research supervisor Professor A. MM Shamsuzzaman. for his valuable guidance, advice, immense help, encouragement and support throughout the study. Likewise grateful appreciation is conveyed to the research co- supervisor Md. Moinul Hoque, Associate Professor, for his constant encouragement, cordial suggestions, cons tructive criticisms and valuable advices to complete the thesis.

The author would like to express his deepest respect and boundless gratitude to all the respected teachers of the Department of Agricutural Botany, Sher-e-Bangla Agricultural University, Dhaka, for their valuable teaching, sympathetic co- operation, and inspirations throughout the course of this study and research work.

The author wishes to extend his special thanks to Chandan, Khirut Hasan, Masum, Nobel, Anis, Shahin and Titu for their help during experimentation.

Special thanks to all other friends for their support and encouragement to complete this study.

The author is deeply indebted to his father and grateful to his respectful mother.

brother and other relatives for their moral support, encouragement and love with cordial understanding.

Finally, the author appreciate the assistance rendered by the staffs of the Department ofAgricutural Botany, Sher-e-Bangla Agricultural University, Dhaka, who have helped him during the period of study.

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The author

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ABSTRACT

A field experiment was conducted at the experimental field of Sher-e-Bangla Agricultural University during July to December 2010 to find out the effect of 1, 2 or 3 seedling(s) per hill on growth. yield and yield components of a modern inbred (BRRI dhan49) and four hybrid (BRRI hybrid dhan2. Heera, La and Aloron) transplant Atnan rice varieties. The experiment was laid out in factorial randomized complete block design with three replications. Results showed that rice cultivars differed significantly in all growth characters, such as, plant height, tillers number, chlorophyll content, dry matter weight of different plant pafls, panicle length, filled grain, unfilled grain, grain filling percentage, 1000-grain weight, grain yield and straw yield. All the varieties exhibited higher amount of chlorophyll over inbred BRRI dhan49 in their flag leaf. Leaf dry matter, stem dry matter and total dry matter accumulation ability higher in inbred BRRI dhan49 compared to all studied hybrid rice varieties. The inbred variety BRRI dhan49 produced the highest grain (5.58 t hi') and straw yield (8.13 t hi').

Numbers of seedling(s) per hill had remarkable influence on number of total tillers per hill and total dry matter production and single seedling per hill gave the highest grain yield (4.20 t hi'). The higher grain yield was attributed mainly to the number of effective tillers per hill, filled grains per panicle and 1000-grain weight. Remarkable grain and straw yield were found from the interaction of BRRI dhan49 planted 1 seedling per hill.

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CHAPTER TITLE PAGE

3.7 Raising of seedling 31

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^3.8 Collection and preparation of initial soil sample 31

3.9 Preparation of experimental land 31

3.10 Fertilizer management 32

3.11 Experimental treatments 32

3.12 Experimental design 33

3.13 Uprooting and transplanting of seedlings 33

3.14 Intercultural operation 34

3.14.1 Gap filling 34

3.14.2 Weeding 34

3.14.3 Application of irrigation water 34

3.14.4 Method of water application 34

3.14.5 Plant protection measures 34

3.15 General observation of the experimental field 35

3.16 Harvesting and post harvest operation 35

3.17 Recording of data 35

3.18 Experimental measurements 36

3.19 Analysis of data 40

4 RESULTS AND DISCUSSION 41

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^4.1 Crop growth characters 41

4.1.1 Plantheight 41

4.1.2 Tiller number 46

4.1.3 Chlorophyll content 51

4.1.4 Leaf blade dry matter weight 54

4.1.5 Cumulative dry matter weight of stem and leaf sheath 58

4.1.6 Total dry matter production 63

4.2.7 Panicle length 68

4.2 Yield contributing characters 71

4.2.1 Filledgrainperm2 71

4.2.2 Number of unfilled grains per m2 72

4.2.3 Filled Grain percentages 73

4.2.4 1000-grain weight 74

4.3 Yield 77

4.3.1 Grain yield 77

4.3.2 Straw yield 80

4.3.3 Biological yield 83

4.3.4 Harvest Index 85

S SUMMARY AND CONCLUSION 88

REFERENCES 91

a APPENDICES 105

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LIST OF TABLES

TABLE TITLE PACE

Plant height of transplanted Ainan rice as influenced by 45 combine effect of variety and seedling(s) number per hill

2 Tiller number of transplanted Aman rice as influenced by

combine effect of variety and seedling(s) number per hill 51 3 Chlorophyll content of flag leaf of transplanted Aman rice 53

as influenced by variety, seedling number per hill or interaction effect of these two factors

4 Leaf blade dry matter weight of transplanted Aman rice as 57 influenced by variety, seedling number per hill or

interaction effect of these two factors

5 Cumulative dry matter weight of stem and leaf sheath of 62 transplanted Aman rice as influenced by variety, seedling

number per hill or interaction effect of these two factors

6 Total dry matter weight of transplanted Arnan rice as 67 influenced by variety, seedling number per hill or

interaction effect of these two factors

7 Paniele length of transplanted Arnan rice as influenced by 70 interaction effect of variety and seedling(s) number per

hill

8 Filled grain, unfilled grain, filling % and 1000 grain 76 weight of transplanted Aman rice as influenced by

combine effect of variety and seedling(s) number per hill

9 Grain yield, straw yield, biological yield and harvest 87 index of transplanted Aman rice as influenced by combine

effect of variety and seedling(s) number per hill

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LIST OF FIGURES

FiGURE TITLE PAGE

Effect of variety on plant height (cm) of transplanted 42 Arnan rice at different growth stages

2 Effect of different seedling(s) numbers per hill on plant 44 height (em) of transplanted Arnan rice at different growth

stages

3 Effect of variety on tiller number of transplanted Aman 48 rice at different growth stages

4 Effect of different seedling(s) numbers per hill on tiller 59 number of transplanted Aman rice at different growth

stages

5 Effect of variety numbers per hill on panicle length of 68 transplanted Arnan rice at different growth stages

6 Effect of different seedling(s) numbers per hill on panicle 69 length of transplanted Aman rice at different growth

stages

7 Effect of variety numbers per hill on grain yield of 78 transplanted Ainan rice at different growth stages

8 Effect of different seedling(s) numbers per hill on grain 79 yield of transplanted Atnan rice at different growth stages

9 Effect of variety numbers per hill on straw yield of 81 transplanted Aman rice at different growth stages

10 Effect of different seedling(s) numbers per hill on straw 82 yield of transplanted Aman rice at different growth stages

11 Effect of variety numbers per hill on biological yield of 83 transplanted Aman rice at different growth stages

12 Effect of different seedling(s) numbers per hill on 84 biological yield of transplanted Aman rice at different

growth stages

13 Effect of variety numbers per hill on harvest index of 85 transplanted Atnan rice at different growth stages

14 Effect of different seedling(s) numbers per hill on harvest 86 index of transplanted Aman rice at different growth stages

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LIST OF APPENDICES

APPENDIX TITLE PACE

1 Map showing the experimental sites under study 105

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^II Weather data 2007. Dhaka 106

III Physiochemical properties of the initial soil 106 IV Means square values for plant height (cm) of 107

transplanted Aman rice at different growth stages

V Means square values for total tiller number of 107 transplanted Aman rice at different growth stages

VI Means square values for chlorophyll content of 108 flag leaf of transplanted Aman rice

VII Means square values for leaf blade dry matter 108 weight of transplanted Aman rice at different

growth stages

VIII Means square values for cumulative dry matter 109 weight of stem and leaf sheath of transplanted

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Aman rice at different growth stages

IX Means square values for total dry matter weight of 109 transplanted Aman rice at different days after

transplanting

X Means square values for panicle length, filled 110 grain, unfilled grain, filling % and 1000 grain

weight of transplanted Aman rice at different growth stages

Xl Means square values for grain yield, straw yield. 110 biological yield and harvest index of transplanted

Aman rice

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LIST OF ACRONYMS AEZ

=

Agro-Ecological Zone

BARC

=

Bangladesh Agricultural Research Council BBS

=

Bangladesh Bureau of Statistics

BINA

=

Bangladesh Institute of Nuclear Agriculture BRRI

=

Bangladesh Rice Research Institute

Cm

=

Centi-meter

Cont'd

=

Continued

cv. Cultivar

DAT

=

Days after transplanting

°

_C

=

Degree Centigrade

DF

=

Degree of freedom

EC

=

Emulsifiable Concentrate

ci al.

=

and others

etc.

=

Etcetera

FAO

=

Food and Agricultural Organization

g

=

Gram weight

Hi

=

Harvest Index

Hr

=

hour

1RRI

=

international Rice Research Institute

Kg

=

kilogram

LV

=

Local variety

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LSD

=

Least significant difference

in

=

Meter

m2

=

Square meter

mm

=

Millimeter

viz.

=

Namely

N

=

Nitrogen

ns

=

Non significant

% =

Percent

CV

% =

Percentage of Coefficient of Variance

P

=

Phosphorus

K

=

Potassium

ppm

=

Parts per million

SAU

=

Sher-e- Bangla Agricultural University

S

=

Sulphur

Zn

=

Zinc

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Chapter 1

Introduction

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INTRODUCTION \ y:

Rice (Oryza saliva L.) is the second most widely grown cereal in the world and it is the staple food for more than half of the world's population. Asia is the leading producer of rice and most Asians get 60% of their calories from rice.

Bangladesh ranks 41h in both area and production and 6th in the production of per hectare yield of rice in the world. It is the staple food of about 160 million people of Bangladesh. Rice cultivation is favored by the hot, humid climate and the large number of deltas across Asia's vast tropical and subtropical areas.

Rice is extensively grown in Bangladesh in three seasons namely, Aus. Arnan and Boro. which covers 80% of the total cultivable area of the country (AIS.

2011). The population of Bangladesh is growing by two million every year and may increase by another 30 million over the next 20 years. Thus. Bangladesh will require about 27.26 million tons of rice for the year 2020. During this time total rice area will also shrink to 10.28 million hectares. Rice yield therefore, needs to be increased by 53.3%. In Bangladesh, rice yield level is far below than that of many other countries like China, Japan, Korea and Egypt where yield is 7.5. 5.9, 7.3 and 7.5 t ha", respectively (FAO. 2009). Horizontal expansion of rice area is not possible in Bangladesh due to limited land resources and high population density. So, the only avenue left is to increase production of rice by vertical means, that is, management practices. The potential for increased rice production strongly depends on the ability to - integrate a better crop management for the different varieties into the existing cultivation. Variety itself is a genetic factor which contributes a lot in

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producing yield and yield components of a particular crop. Yield components are directly related to the variety and neighboring environments in which it grows. Earlier literatures indicate that there are marked differences in yield and ancillary characteristics among rice varieties (Choudhury and Bhuiyan, 1991:

Miah el aL, I989).e the year 2010, among the A,nan rice varieties high yielding modem varieties covered 66.63% and yield was 2.49 t hi' and local varieties covered 24.97% and yield was 1.58 t hi' (BBS, 201 It is the farmers who have gradually replaced the local indigenous low yielding rice varieties by high yielding ones and modem varieties of rice developed by Bangladesh Rice Research Institute (BRRI) only because of getting 20 to 30%

more yield unit land area (Shahjahan, 2007). In Bangladesh as well as in the world rice research is predominantly being conducted to develop modem high yielding and hybrid varieties.

Planting density as a management practice in transplanted rice culture constitutes the number of seedling per hill or per unit area. Number of productive tillers and their greater growth both quantitative and qualitative growth are influenced by number of seedling per hill. Optimum seedling(s) per hill enables rice plants to grow properly both in their aerial and underground parts by proper utilization of radiant energy, nutrients, space and water.

1-lowever, controversy is found regarding the number seedlings planted per hill.

Nakano and Mizushima. (1994) reported that grain yield is negatively correlated with increasing the number of seedling per hill. while Shah ci al.

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(1991) found that the different number of seedling per hill had no effect on the number of panicles per hill. Different level of seedling(s) per hill had no effect on panicles per hill, grains per panicle and grain yield (Shah etal., 1991). Wen and Yang (1991) found that effective panicles, the number of grains per panicle and the 1000- grain weight were also higher with only one seedling per hill.

Obulamma et at (2002) recorded the highest grain yield, crop growth rate and net assimilation rate from one seedling per hill. Panda ci at (1999) found that grain yield was highest with 4 seedlings per hill. Biswas and Salokhe (2001) revealed similar yield of rice by planting 2-4 vegetative tillers per hill. Excess number of seedling hill" may produce more tillers per unit of land area resulting in mutual shading, lodging and lead to production of more straw instead of grain. While the least number of seedlings per hill may produce insufficient tiller, keeping space and nutrients unutilized resulting in less number of panicles per unit area, resulting poor yield (Miah et at, 2004). (

'For the ever-increasing population of Bangladesh, the increasing demand for rice will have to meet with lesser area of land, lesser amount of water, lesser number of labour and lesser amount of pesticides. Hybrid rice ^offersto break the yield ceiling of conventional semi-dwarf rice varieties. Hybrid rice technology has been introduced through IRRI, BRRI and commercial seed companies of India and China during the last ten years and has already gained positive experience in the Boro season. In Aman season, however, available information regarding the yield and yield contributing characters, both morpho-

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physiological characteristics of hybrid rice varieties are meager in Bangladesh.

That is why, it is a prime need to conduct more research work to find out and develop sustainable technologies regarding hybrid rice cultivation under the prevailing local conditions in the Aman season. For example. Julfiquar et at (1998) observed that the modem inbred rice varieties in Bangladesh had a longer growth duration of 135-150 days in Aman season with a low daily yield, while high daily yield in hybrid rice was due to its short duration of 120-130 days. Therefore, it is postulated that if hybrid rice is introduced, crop duration can be reduced by 20-40 days. /

Considering the above proposition, the present study was undertaken with the following objectives:

To investigate the tiller population and dry matter accumulation of hybrid rice varieties in the Aman season.

To compare the yield potential of hybrid rice with inbred rice in the Aman season.

To determine the effect of seedling densities on the yield of hybrid rice in the Aman season.

To investigate interaction effect of cultivars and seedling densities on the growth, yield and yield contributing characters of Aman rice.

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Chapter 2

Review of literature

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REVIEW OF LITERATURE

Number of seedlings per hill is an important factor as it influences the plant - population per unit area, availability of sunlight, nutrient competition, photosynthesis, respiration etc., which ultimately influence the growth and development of the crop. Considering the above points, available literature was reviewed under different seedling(s) number per hill for rice varieties.

2.1 Effect of variety

Variety itself is the genetical factor which contributes a lot for producing yield and yield components. Different researcher reported the effect of rice varieties on yield contributing component and grain yield. Some available information and literature related to the effect of variety on the yield of rice are discussed below:

2.1.1 Effect on growth characters

2.1.1.1 Plant height

Masum ci at (2008) found that plant height of rice affected by varieties in Arnan season where Nizershail produced the taller plant height than BRRI dhan44 at different days after transplanting (DAT).

BINA (1993) evaluated the performance of four rice varieties (IRATOM 241, BRI4, BINA13 and BINAI9). It was found that varieties differed significantly in respect of plant height.

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BRRI (1991) observed that plant height differed significantly among BR3, BR 11, BR 14, Pajam and Zagali varieties in the Born season.

- Hosain and Alam (1991) found that the plant height in modern rice varieties BR3. BRI 1, BRI4 and Pajam were 90.4, 94.5, 81.3 and 100.7 cm. respectively.

Miah ci al. (1990) conducted an experiment where rice cv. Nizersail and mutant lines Mut. NSI and Mut. NSS were planted and found that plant height were greater in Mut. NSI than Nizersail.

Shamsuddin ci at (1988) conducted a field trial with nine different rice varieties and observed that plant height differed significantly among the varieties tested.

Sawant cial. (1986) conducted an experiment with the new rice lines R-73-1-1, R.-7 11 and the traditional cv. Ran and reported that the traditional cv. Ratna was the shortest.

2.1.1.2 Tillering pattern

Masuni et at (2008) stated that number of total tillers per hill was significantly influenced by cultivars at all stages of crop growth. Nizersail was achieved maximum (25.63) tiller at 45 DAT, then with advancement to age it declined up to maturity, whereas in the case of BRR1 dhan44, maximum (18.92) tiller production was observed around panicle initiation stage at 60 DAT and also - then with advancement to age it declined up to maturity.

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Devaraju c/ aL (1998) in a study with two rice hybrids, Karnataka Rice Hybrid 1 (KRHI) and K.amataka Rice 1-lybrid-2(KRI42), using HYV 1R20 as the check, found that KRH2 out yielded 1R20. In 1R20t the tiller number was

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higher than that of KRH2.

Islam (1995) in an experiment with four rice cultivars vi:. BR 10, BR! 1, BR22 and BR23 found that the highest number of non bearing tillers per hill was produced by cultivar BR 11 and the lowest number by BR 10.

Chowdhury ci at (1993) reported that the cultivar BR23 showed superior performance over Pajani in respect of yield and yield contributing characters i.e. number of productive tillers per hill.

1-lossain and Alam (1991) also found that the growth characters like total tillers per hill differed significantly among 3R3, BRI 1, Pajam and Jaguli varieties in the Born season.

Idris and tvlatin (1990) stated that number of total tillers per hill was identical among the six varieties studied. Devaraju ci at (1998) also reported that the increased yield of KRH2 was mainly attibuted due to the higher number of productive tillers per plant.

2.1.1.3 Total dry matter production

Masum ci at (2008) found that total dry matter production differed due to - varieties. Total dry matter of BRRI dhan 44 and Nizershail significantly varied

at different sampling dates.

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Amin et at (2006) conducted a field experiment to find out the influence of variable doses of N fertilizer on growth, tillering and yield of three traditional rice varieties (Jharapajam. Lalmota, Bansful Chikon) was compared with that of a modem variety (KK4) and reported that traditional varieties accumulated higher amount of vegetative thy matter than the modem variety did.

Son c/aL (1998) reported that dry matter production of four inbred lines of rice (low-tillering large panicle type). YR I 5965ACP33, YR 171 O4ACP5, YRI 6510- B-B-B-9, and YR 16512-B-B-B-I 0, and cv. Namcheonbyeo and Daesanbyeo, were evaluated at plant densities of 10 to 300 plants n12 and reported that dry matter production of low-tillering large panicle type rice was lower than that of Namcheonbyeo, regardless of plant density.

- 2.1.2 Effect on Panicle length, filled grains per panicle, unfilled grains per panicle, filled grain percentage, 1000-grain weight

Wang ci aL (2006) studied the effects of plant density and row spacing (equal row spacing and one seedling per hill , equal row spacing and 3 seedlings per hill , wide-narrow row spacing and one seedling per hill, and wide-narrow row spacing and 3 seedlings per hill) on the yield and yield components of hybrids and conventional cultivars of rice. Compared with conventional cultivars, the hybrids had larger panicles, heavier seeds, resulting in an average yield increase of 7.27%.

Obulammna ci at (2004) recorded hybrid APFIR 2 had significantly higher grain yield than hybrid DRRH I. The increased grain yield was due to increase in

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number of panicles per m2 and number of filled grain per panicle in hybrid API-JR 2 than hybrid I)RRH 1.

Guilani ci al. (2003) studied on crop yield and yield components of rice cultivars (Anboori. Champa and LD183) in Khusestan, Iran, during 1997. They observed that grain number per panicle was not significantly different among cultivars. The highest grain number per panicle was obtained with Anboori.

Grain fertility percentages were different among cultivars. Among cultivars, LD 183 had the highest grain weight.

Ahmed c/ aL (1997) conducted an experiment to compare the grain yield and yield components of seven modem rice varieties (BR4. BR5, BR 10, BR] 1, BR22, BR23, and BR25) and a local improved variety, Nizersail. The fertilizer dose was 60-6040 kg ha1 of N, P205 and K20, respectively for all the varieties and found that percent filled grain was the highest in Nizersail followed by BR25 and the lowest in BRI 1 and BR23.

BRRI (1994) studied the performance of BRI4, BR5. Pajam, and Tulsimala and reported that Tulsimala produced the highest number of filled grains per panicle and BR14 the lowest

BINA (1993) evaluated the performance of four varieties IRATOM 24, BRI4.

BINAI3 and BINAI9. They found that varieties differed significantly on panicle length and sterile spikelets per panicle. It was also reported that varieties BJNA13 and BINAI9 each had better morphological characters like

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more grains per panicle compared to their better parents which contributed to yield improvement in these hybrid lines of rice.

BRRI (1991) also reported that the filled grains per panicle of different modern

varieties were 95-100 in BR3. 125 in BR4, 120-130 in BR22 and 110-120 in BR23 when they were cultivated in the Anton season.

Idris and Matin (1990) also observed that panicle length differed among the six rice varieties and it was longer in 1R20 than in indigenous high yielding varieties.

Singli and Gangwer (1989) conducted an experiment with rice cultivars C-I 4- 8. CR-1009. IET-5656 and 11-6314 and reported that grain number per panicle. 1000-grain weight were higher for C- 14-8 than those of any other three varieties.

Rafey et at (1989) carried out an experiment with three different rice cultivars and reported that weight of 1000 grains differed among the cultivars studied.

Shamsuddin ci at (1988) also observed that panicle number per hill and 1000- grain weight differed significantly among the varieties.

Kamal ci at (1988) evaluated BR3, IR.20, and Pajam2 and found that number of grain per panicle were 107.6, 123.0 and 170.9 respectively, for the varieties.

Costa and Hoque (1986) studied during k/tarifF! season, 1985 at Tangail FSR - site. Palima, Bangladesh with five different varieties of 1. anton BR4. BRIO,

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BRI I. Nizersail and indrasail. Significant differences were observed in panicle length and number of unfilled grains per panicle among the varieties tested.

- 2.1.3 Effect on grain yield and straw yield

Swain ci at (2006) reported that the control cultivar 1R64, with high translocation efficiency and 1000-grain weight and lowest spikelet sterility recorded a grain yield of 5.6 t ha4 that was statistically similar to the hybrid line PA620I.

MoIla (2001) reported that Pro-Agro6201 (hybrid) had a significant higher yield than 1ET4786 (HYV), due to more mature panicles per i112, higher number of filled grains per panicle and greater seed weight.

Patel (2000) studied the varietal perfommnce of Kranti and 1R36. He observed that Kranti produced significantly higher grain and straw yield than 1R36 did.

The mean yield increased with Kranti over 1R36 was 7.1 and 10.0% for grain and straw, respectively.

Julfiquar ci al. (1998) reported that ^BRRIevaluated 23 hybrids along with three standard checks during Boro season. It was reported that five hybrids (1R58025A/lR54056, 1R54883, PMS8AIIR46R) out yielded the check varieties (BRI4 and BRIG) with significant yield difference.

Julfiquar c/aL (1998) reported that thirteen rice hybrids were evaluated in three locations of BADC farm during the Boro season of 1995-96. Two hybrids out yielded the check variety of same duration by more than 1 t hi'.

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Rajendra ci at (1998) carried out an experiment with hybrid rice cv. Pusa 834 and Pusa 1-1R3 and observed that mean grain yields of Pusa 834 and Pusa HR3 were 3.3 t ha 4 and 5.6 t hi'. respectively.

BRRI (1997) reported that three modem upland rice varieties namely, BR 20, BR 21, BR 24 was suitable for high rainfall belts of Bangladesh. Under proper management, the grain yield was 3.5 ton for BR20, 3.0 ton for BR21 and 3.5 ton for BR24 hi'.

Nematzadeh ci at (1997) reported that local high quality rice cultivars 1-lassan Sarai and Sang-Tarom were crossed with improved high yielding cultivars Amol 3, PND160-2-1 and RNR1446 in all possible combinations and released in 1996 under the name Nemat, which gave an average grain yield of 8 t had, twice as much as local cultivars.

BRRI (1995) conducted an experiment to find out varietal performances of BR4. BRIO, BRI 1, BR22. BR23 and BR25 varieties including two local checks ChaHish and Nizersail, produced yields of 4.38, 3.18, 3.12, 3.12 and 2.70 5 t hi', respectively.

Chowdhury ci at (1995) studied seven varieties of rice, of which three were native (Maloti, Nizersail and Chandrashail) and four were improved (BR3.

BRI 1, Pasam and Mala). Straw and grain yields were recorded and found that both the grain and straw yields were higher in the improved than the native varieties.

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Liu (1995) conducted a field trial with new indica hybrid rice 11-You 92 and found an average yield of 7.5 t hi' which was 10% higher than that of standard hybrid Shanyou 64.

In field experiments at Gazipur in 1989-1990 rice cv. BRI I (weakly photosensitive), BR22, BR23 and Nizersail (strongly photosensitive) were sown at various intervals from July to September and transplanted from August to October. Among the cv. 13R22 gave the highest grain yield from most of the sowing dates in both years (Ali €1 at, 1993).

Chowdhuxy ci al. (1993) reported that the cultivar BR23 showed superior performance over Pajam in respect of yield and yield contributing characters i.e., grain yield and straw yield.

Suprihatno and Sutaryo (1992) conducted an experiment with seven IRRI hybrids and 13 Indonesian hybrids using IRG4 and way-seputih. They observed that TR64 was highest yielding, significantly out yielding IR646161-1. 1R64618, lR646 IOH and lR62829A11R54 which in turn out yielded way-seputib.

Chandra c/at (1992) reported that hybrid 1R58025A out yielded the 1R62829A hybrids and the three control varieties Jaya. 1R36 and hybrids 1R58025A x 9761-191 B. and 1R58025A IR58025Ax I R35366-62- I -2-2-3R.

Hossain and Alam (1991) studied farmers production technology in haor area and found that the grain yield of modern varieties of flora rice were 2.12. 2.18, 3.17, 2.27 and 3.05 t hi'. with 3R14. BRI 1, BR9. IRS and 8R3, respectively.

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In evaluation of performance of four HYV and local varieties-BR4, BR 16, Rajasail and Kajalsail in arnan season, BR4 and BR16 were found to produce more grain yield among four varieties (BRRI, 1985).

2.2 Effect of seedling numbers per hill

2.2.1 Effect on growth character

2.2.1.1 Plant height

Bozorgi ciaL (2011) carried out a field experiment and found that plant height was significantly affected by number of seedling(s) per hill, 1 seedling per hill gave the maximum plant height.

Roshan ci al. (2011) stated that number of seedling(s) per hill did not significantly influence the plant height and grain yield.

1-lasanu77aman ci aL (2009) showed that plant height was decreased with increasing number of seedlings per hill. The maximum plant height was observed with I seedling per hill which was statistically similar to 2 and 3 seedlings per hill. Three and 4 seedlings per hill also gave identical results.

Hushine (2004) reported that number of seedling per hill significantly influenced all the growth parameters except plant height.

Miah ci aL (2004) carried out an experiment to determine the effects of planting rate of 1, 2, 3 or 4 seedlings per hill on the yield and yield components of transplanted rice cv. BINA dhan 4. Plant height was highest with planting of

I and 2 seedlings per hill, respectively.

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Faruque (1996) reported that plant height increased with the increased number of seedling(s) per hill, whereas Shah et at (1991) reported that plant height increased with decrease in seedling number per hill.

2.2.1.2 Tillering pattern

11asanuzzaman ci at (2009) showed that tiller production was significantly affected with number of seedlings per hill. The maximum number of tillers was observed with 2 seedlings per hill. Significant changes in tiller number were observed between I and 2 seedling per hill and thereafter the result was identical.

Islam ci

ci.

(2008) stated that tillers per hill significantly affected by number of seedlings per hill and it was gradually increased with the increasing number of - seedlings per hill. The highest value was obtained from 4 seedlings per hill and

the lowest from I seedling per hill.

l3aloch ca' at (2006) initiated studies for two consecutive years to find out the effect of time of transplanting and seedlings per hill (I. 2.

3

or 4) on the productivity of rice in Dera Ismail Khan district of North West Frontier Province (NWFP), Pakistan. They reported that the maximum productive tillers (548.3 m 2) were recorded with 4 seedlings hill 1 followed by 533.3 productive tillers in 2 with

3

seedlings per hill on the same date.

Inaba and Kitano (2005) reported on tiller production of rice plants (cv.

Kinuhikari) transplanted at different seedling numbers per hill (1.

3.

5, 7 and 9 seedlings per hill) in Japan. Tillering duration decreased with increasing number of seedlings per hill (density), and that in the 9-seedling per hill was

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two weeks shorter than that in the 1-seedling hills. The higher the seedling density, the earlier was the time of tillering. In I to 5-seed1ing hills, the tiller production rate increased with increasing seedling density, but the rate decreased in the hills with higher seedling densities.

Park ci aL (1998) stated that increasing plant density per hill increased total tiller numbers but decreased the proportion of effective tillers.

Shrirame el aL (2000) carried out a field experiment during the khanj 1996 in Nagpur, Maharashtra. India on rice cv. TNRHIO. TNRI-l13 and TNRI-118 were grown at 1, 2 or 3 seedlings per hill and found that two seedlings per hill gave significantly higher number of tillers per hill than three seedlings per hill.

Hossain and Haque (1990) reported that the number of basal tillers plot1 - increased with increasing seedling number.

Hussain ci al. (1989) carried out an experiment with rice cv. Baspati and observed that the number of tillers increased upto 16.4 per hill with increasing number of seedlings per hill.

Research results at 131NA revealed that the number of seedlings per hill of four rice varieties of Aus rice viz. lratom24, lratom38, BR3 and Pajam with the number of seedling per hill were I, 2, 3 and 4. It was found that the number of effective tillers per hill increased progressively from I seedling per hill, seedlings number 2, 3 and 4 gave statistically same effective tillers per hill

- (BINA. 1987).

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Islam (1980) conducted an experiment to determine the suitable number of seedling per hill for transplanting Anion rice cv. Nizersail, Tilackchari and Badshabog. The results revealed that 2-3 seedlings per hill were as good as 3-4 seedlings per hill with respect to effective tillers production per hill.

Patniswamy and Gomez (1976) reported that number of total tillers per hill increased with increasing number of seedlings per hill.

2.2.1.3 l'otal dry matter production

Masum ci at (2008) found that total dry matter production differed due to variation of different seedling(s) number per hill. He found that dry matter production increased with the increase of seedling density per hill.

Obulanima ci al. (2002) carried out an experiment with hybrid rice DPRH-1 and APHR-2. The treatments were 4 spacing and 1, 2, or 3 seedlings per hill. In that study I seedling per hill produced the highest grain yield, while 3 seedlings per hill had the highest leaf area index and dry matter production.

2.2.2 Effect on panicle length, filled grains per panicle, unfilled grains per panicle, filled grain percentage, 1000-grain weight

Islam ci cii. (2008) found that panicle length was not influenced by the number of seedlings per hill. Number of grain per panicle increased with the increasing number of seedlings up to 3 seedlings and thereafter it declined. Filled grains per panicle and weight of 1000-grain were not significantly influenced by

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number of seedlings as it might be controlled by genetic make-up of the variety studied.

a Wang ci at (2006) reported that planting of one seedling per hill was suitable for hybrids, whereas planting of 3 seedlings per hill was suitable for conventional cultivars.

Pariyani and Naik (2004) reported that planting of one or two seedlings per hill did not show significant variations in yield attributes like panicle length, filled grains, sterile spikelets and 1000-grains weight of rice.

Kannakar ci at. (2002) showed that number of effective tillers per hill and straw yield were the highest with 6 seedlings per hill while panicle length and grains per panicle were the highest with 2 seedlings per hill in case of late transplant arnai; rice.

Bisht ci al. (1999) conducted a field experiment on hybrid variety PRU I transplanting with 1. 2 and 3 seedlings per hill and reported that number of panicles and total spikelets increased with 2 or 3 seedlings per hill.

Rajarathinam and Balasubrarnaniyan (1999) found that the planting 1 seedling per hill gave similar results to planting 2 seedlings per hill in respects of yield parameters (panicles m 2. panicle weight and length, grains per panicle, filled grains per panicle, filled grain percentage and 1000-grain weight) of hybrid rice cv. CORI-l-2.

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Nakano and Mizushima (1994) elucidated the effect of the number of seedling per hill on yield components and yield, rice cv. Nipponbare and Hourei, which were transplanted at three levels (1, 4. and 7) and two levels (4 and 7) of the seedling number per hill in 1984 and 1985, respectively. In the higher seedling number per hill the number of filled grains per panicle and the percentage of filled grain were smaller. The 1000-grains-weight was not affected by the seedling number per hill.

Wen and Yang (1991) reported that latc rice yields in a double cropping system were higher with I seedling per hill than with 4 seedlings per hill. The proportion of effective panicle, the number of grains per panicle and 1000- grain weight were also higher with only I seedling per hill.

Singh (1990) observed that panicle per hill and grain per panicle increased with increased seedlings per hill, but panicle length, filled spikelets per panicle and seed size decreased.

Rameswamy et

al.

(1987) reported that increasing number of seedlings per hill had an adverse effect on yield parameters of rice. All yield parameters were reduced with more than two seedlings per hill.

Singh c/ at (1987) conducted an experiment with seed rate in nursery and seedlings per hill on yield of transplanted rice. They found that grains per panicle and number of seedlings per hill had no significant effect on yield.

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2.2.3 Effect on grain yield, straw yield, biological yield and harvest index

Bozorgi ci at (2011) reported that the highest grain yield, harvest index and a number of grain per panicle were recorded from 3 seedlings per hill and lowest from 1 seedling per hill. The maximum amount of straw yield and biological yield were recorded from 5 seedlings per hill.

Hasanuzzaman ci aL (2009) stated that grain yield was obtained maximum with 2 seedlings per hill which is statistically identical with 1 seedling per hill. Grain yield were decreased with transplanting of higher number of seedlings (3 or 4 seedlings per hill). Straw yield were showed inverse results. Biological yield of rice was not affected significantly with variable number of seedling(s) per hill.

Harvest index was significantly affected by the number of seedling(s) per hill and the highest harvest index was obtained from I seedling per hill. Harvest index significantly decreased with the transplanting of 3 or more seedlings per hill.

Islam el at (2008) showed that grain yield increased with the increasing of number of seedlings up to 3 seedlings per hill and it was identical to that of 4 seedlings per hill but the lowest was in 1 seedling per hill. increasing seedling number per hill increased grain yield depending on the seedling age. Straw yield was not significantly influenced by the number of seedlings per hill.

Baloch ci at (2006) also reported that among seedlings per hill the highest e

paddy yield and net return were obtained with I seedling per hill. According to

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their opinion the use of more seedlings per hill not only added to cost but was also a mere wastage of natural resources.

Nayak ci at (2006) studied on the effect of planting varying number of seedlings per hill (I, 2 and 3 seedlings per hill) on yield components as well as yield of 3 hybrid cultivars (Pro-Agro6201, CNHR-3 and PAC-801) and one high-yielding cultivar (Khitish) of rice. The hybrid cultivars exhibited better performance in terms of yield components and yield at 2 seedlings per hill than at I seedling per hill but there was no yield advantage by planting 3 seedlings per hill over 2 seedlings per hill. Khitish performed better at 3 seedlings per hill than at I or 2.

Zhang ci at (2004) conducted a field experiment with Ill You 98 (sown on II May 2002) in Hefei. Anhui, China. The effects were investigated of different transplanting densities and number of seedlings per hill (1 and 2) on some agronomic traits and grain yield-related indices. Although differences in plant height, panicle length and 1000-grain weight were insignificant but extremely significant differences in grain yield were noted. Crop management including reasonably close planting and 2 seedlings per hill resulted in relatively high grain yield. For yields of more than 10.0 t ha-', the transplanting density should be 281300 hills per ha at 2 seedlings per hill or 365800 hills per ha at I seedling per hill.

s Rajesh and Thanunathan (2003) conducted an experiment on traditional Kambanehamba rice variety in Tamil Nadu, India, during the 2000/01 samba

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season. The seedling age (30, 40 and 50 days), number of seedlings (2 and 4 seedlings per hill) and spacing (20x15. 20x10 and 15x15 cm) were tested.

Planting of 2 seedlings per hill recorded the maximum grain yield of 2.85 and 2.65 t haS' in experiments I and II. respectively.

Dongarwar ci al. (2002) carried out an experiment with hybrid rice KJTRH-1 with 3 spacing (20 x 20, 20 x 15 and 20 x 20 cm2) and 2 levels of seedlings (I and 2 seedlings per hill). Irrespective of spacing treatments planting of one seedling per hill was on at par with planting of two seedlings per hill in respect of grain yield.

Islam ci al. (2002) conducted an experiment with fine rice cv. Kalizira including three hill densities viz. 25 cm x 20 cm, 25 em x 15 cm. 25 cm x 10 cm and two levels of seedlings per hill viz. 2 seedlings per hill and 4 seedlings per hill. The highest grain yield was recorded form 25 cm x 20 cm spacing and 2 seedlings per hill.

Kabir (2002) carried out an experiment to find out the effect of variety and number of seedlings per hill on yield and yield contributing characters of born rice. The experiment comprised of three varieties viz Sonar Bangla I, BINA dhan 5 and B INA dhan 6 and four different numbers of seedlings per hill viz. 1.

2, 3 and 4 seedlings per hill. Number of seedlings differed significantly in respect of growth characters and yield attributes. The highest grain yield (5.37 t ha1) was obtained from 2 seedlings per hill and the lowest grain yield (4.58 t haj was obtained from single seedling per hill which was statistically similar

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to 3 seedlings per hill (4.77 t hi) and 4 seedlings per hill (4.35 t ha'). The highest straw yield (6.52 t ha') was obtained from 2 seedlings per hill and the lowest one (5.11 t ha4 ) was obtained from 4 seedlings per hill.

Molla (2001) reported that seedlings per liii! significantly influenced the number of tillers, mature panicles per in2 and yield of rice. Two seedlings per hill had significantly higher yield than one seedling, including other parameters, in hybrids. For HYV, no significant response was obtained by increasing the number of seedlings from 3 toG.

Shrirame ci at (2000) reported that one seedling per hill gave significantly higher harvest index (Ml) but grain yield were not affected by seedlings number per hill.

Srivastava and Tripathi (2000) carried out an experiment where rice cv. Hybrid 6201 and R 320-300 were grown at 20 cm x IS cm or 15 cm x 10cm spacing at 1. 2 and 3 seedlings per hill and observed that cv. R 320-300 were mown at the 15 cm x 10 cm spacing at 2 seedlings per hill produced the highest grain yield of 7.59 t hi'.

An experiment was conducted at BRR1 to find out the effect of seedling number on the panicle production and yields of a local variety Kumragoin transplanting at 1. 3. 6 and 9 seedlings per hill. The results revealed that panicle and grain yield did not differ significantly due to seedling number per hill (BRRI. 1999).

-a.

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Srinivasulu ci al. (1999) conducted an experiment on rice hybrids APHR- 1 and APHR-2 and the conventional variety Chaitanya, planted with I or 2 seedlings per hill and found that planting of two seedlings per hill of Chaitanya recorded significantly higher grain yield than one seedling per hill but in case of hybrids both the treatments were statisticaily identical.

Asif ci al. (1997) conducted an experiment with rice cv. Basmati 385 grown at 1, 2 or 3 seedlings per hill and observed that grain yield was highest at 2 seedlings per hill

Banik ci al. (1997) conducted a field experiment in 1993-95 in Bthar with 30-, 40-. 50-, or 60-day old rice cv. Pankaj and Pamation seedlings were transplanted at 2, 4. 6 and S seedlings per hill. They reported that yield was the highest with 4 seedlings per hill (4.22 t hi').

Paraye and Kandalkar (1994) conducted an experiment with 3 rice cultivars and showed that similar grain yields were obtained from planting 3 or 6 seedlings per hill.

An experiment was conducted at BINA with the number of seedlings per hill of three rice varieties in Born season viz. Iratom 24, BRI4 and 8R3 and three number of seedlings per hill viz. 1, 2 and 3 seedling(s) per hill. It was found that number of seedlings per hill produced significant effect on filled grains per panicle and significant higher yield by planting 4-5 seedlings per hill compared to 2-3 seedlings per hill (BINA, 1993).

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Chowdhury c/aL (1993) conducted an experiment with 2, 4 and 6 seedlings per hill to study their effect on the yield components of rice cv. BR23 and Pajam during the ainan season. They reported that 6 seedlings per hill gave the highest grain and straw yields.

Rao and Reddy (1993) conducted a field experiment with rice cv. Rasi in the kharif (monsoon) season at 33, 44, 50, 67 and 200 hills nf2 with I. 2, 4, 6 and 8 seedlings per hill. They reported that grain yield increased with decreasing spacing from 33 to 200 hills m 2 with 1 seedling per hill. When tO seedlings per hill were planted yield decreased at the widest spacing.

An experiment was conducted at BRRI with a local variety Kumaragoir at 25 fl-

60

VI en' x 15 cm and 25 cmx 45 cm spacing and 1, 3, 6 and 9 seedlings per hill. The results showed that with any spacing, seedling mortality decreased markedly with an increase in the number of seedlings per hill, but spacing appraised to had no marked effect on seedling mortality (BRRI, 1992).

Prasad ci at (1992) conducted an experiment with 2, 3, 4 and 5 seedlings per hill to study their effect on yield and yield components of rice cv. Sarjoo-52 and found that for all factors 4 seedlings per hill were better. A similar experiment was conducted by Singli and Singh (1992) with 2, 4 and 6 seedlings per hill of rice cv. fvladhukar. They found that for all factors 4 seedlings per hill were better for grain yield.

BRRI (1991) was conducted another study to find out the effect of seedling number (2, 3, 4 and 5 seedlings per hill) on the grain yield and yield a

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components of BR3, BR9 and BR 14. There was no significant effect of seedling number on the yield of BR3 and BRI4. Planting of 4-5 seedlings per hill gave significantly higher yield in BR9 than

2-3

seedlings per hill although such differences were not represented in yield components.

BRRI (1990) was conducted an experiment to find out the optimum plant population required for a satisfactory grain yield of rice at Joydebpur and l-labiganj at the combination of different plant spacing with 2-3 and

5-6

seedlings per hill. The highest grain yield was obtained by using 5-6 seedling per hill in both the places. Increase in seedlings number from 2-3 to

5-6

seedlings per hill produced better grain yield in most cases.

Zhang and Huang (1990) studied the effects of seedlings per hill of medium - duration rice variety, transplanted at 1-5 seedlings per hill and found that 2 or 3 seedlings per hill gave best yield with increasing grain yield but harvest index were unaffected by the different number of seedlings per hill. On the other hand Budhar ci at (1989) observed paddy yield, yields in early maturing rice cv. CR666-I8 grown with 2 or 4 seedlings per hill though the yield difference was not significant.

In an experiment of Karim c/ at (1987), Nizersail was planted with 1, 2, 3, 4 and

5

seedlings per hill and observed that highest grain yield of Nizersail was obtained with 4 followed by 3 seedlings per hill while I seedling per hill yielded the lowest.

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Sarma ci aL (1979) observed that increased grain yield when seedling(s) per hill was increased from 2 to 4 seedlings per hill.

Kang and Choi (1978) reported that in rice cultivar Tongil when grown with 1, 3. 5 and 7 seedlings per hill, shortened the growth duration and increased the ripened grain ratio with increasing number of seedlings per hill. But the effect was not significant in the early season. Increasing the number of seedlings per hill increased grain yields in Tongil, especially in late-season crops but not in cv. Milyang 15. For early, 3-5 seedlings per hill and for late 5-6 seedlings per hill produced the highest yield.

Shahi and Gill (1976) observed that there was no significant difference in paddy yields of dwarf rice cultivar Jaya grown at a spacing of 20 cm X 20 cm or 15 cm X 15 cm with 1-4 seedlings per hill .Yield tended to be the highest at 20 cm X 20 cm and with 2 seedlings per hill.

From the reviews cited and discussed above, it can be concluded that variety, seedling(s) number per hill and interaction of this two factors have tremendous effect on growth, yield and yield component of hybrid and inbred varieties of

(Ufl(lfl rice.

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Chapter 3

Materials and Methods

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MATERIALS AND METhODS

This chapter presents a brief description of the experimental period, experimental site, climatic conditions, planting materials, treatments, experimental design and layout, crop growing procedure, fertilizer application, intercultural operations, data collection and statistical analysis. that were used in the experiment.

3.1 Experimental period

The experiment was conducted during the period from July to December, 2010 in ^Amatiseason.

3.2 Site description

The experiment was conducted in the Sher-e-Bangla Agricultural University farm, Ohaka, under the agro-ecological zone of Modhupur Tract, AEZ-28. For better understanding, the experimental site is shown in the Map of AEZ of Bangladesh in Appendix 1.

3.3 Climate

The experimental area was under the sub-tropical climate that is characterized by high temperature, high humidity and heavy rainfall with occasional gusty winds in khar?f season (April-September) and less rainfall associated with moderately low temperature during the ^raM season (October-March). The weather data during the study period at the experimental site are shown in Appendix 11.

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3.4 Soil

The farm belongs to the general soil type, Shallow Red Brown Terrace Soils - under Tejgaon Series. The land was above flood level and sufficient sunshine was available during the experimental period. Soil samples from 0-15 cm depths were collected from the experimental field. The analyses were done at Soil Resource and Development Institute (SRDL), Dhaka. The physicochemical properties of the soil are presented in Appendix III.

3.5 Crop I planting material

Five varieties of Aman rice, namely, BR.R1 dhan49. BRRI hybrid dhan2, Heera2, Tia and Aloron were used as test crops in the experiment.

3.5.1 Description of rice cultivars

BRRI dhan49: The variety was developed through hybridization in 2008 by

Bangladesh Rice Research Institute and grown in anan season. The variety is recommended for cultivation in medium high lands and medium low lands where the maximum tidal depths not exclude 50 cm. This cultivar matures at 135-140 days of planting. It attains a plant height of 100-110 cm. The variety has a power of higher disease resistance. Rain and storm cannot damage the rice much. The cultivar gives an avenge yield of 5.5 t ha

BRRI hybrid dhan2: The variety was released in 2008 through Bangladesh Rice Research Institute. BRRI hybrid Dhan2 is mainly suitable for boro season (October-March). It is medium fine and tasty. This cultivar requires more than

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150 days for maturation. It attains a plant height of 100-110 cm. The cultivar gives an average yield of 8.0 t hi'.

a Heera2: Heera2 is a hybrid variety and was imported from China and approved by the National Seed Board of Bangladesh. The variety is well adapted the climatic conditions of Bangladesh. Supreme Seed Company Pvt. Ltd. is the importer of this rice in Bangladesh. The plant type is semi dwarf (95-105 cm), growth duration is 145-150 days and its average grain yield ranges from 9 to 10 t hi.

Tia: ha is a hybrid rice developed at China. It is well adapted with the climatic conditions of Bangladesh. BRAC (Bangladesh Rural Advancement Committee) is the sole agent for this in Bangladesh. The average plant height is 90-100 cm.

The growth duration is 103-140 days. This variety has a yield potentiality up to IOthi'

Aloron It is a hybrid rice developed at China and marketed in Bangladesh by ACI (Advanced Chemical Industries) Ltd. Aloron has the ability to produce grain yield of 8.5-9.5 t hi', growth duration 104-130 days, plant type is semi dwarf(100-120 cm), and suitable for irrigated soils.

3.6 Seed collection and sprouting

Seeds were collected from BRRI (Bangladesh Rice Resaerch Institute), Gazipur. Healthy seeds were selected following the standard method. Seeds were immersed in water in a bucket for 24 hours. These were then taken out of

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water and kept in gunny bags. The seeds started sprouting after 48 hours which were suitable for sowing in 72 hours.

3.7 Raising of seedlings

A common procedure was followed in raising seedlings in the seedbed. The nursery bed was prepared by puddling with repeated ploughing followed by laddering. The sprouted seeds were sown as uniformly as possible. Irrigation was gently provided to the bed as and when needed. No fertilizer was used in the nursery bed.

3.8 Collection and preparation of initial soil sample

The initial soil samples were collected before land preparation from a 0-15 cm soil depth. The samples were collected by means of an auger from different location covering the whole experimental plot and mixed thoroughly to make a composite sample. After collection of soil samples, the plant roots, leaves etc were picked up and removed. Then the sample was air-dried and sieved through a 10-mesh sieve and stored in a clean plastic container for physical and chemical analyses.

3.9 Preparation of experimental land

The experimental field was first opened on 26 July, 2010 with the help of a power tiller, later the land was irrigated and prepared by three successive ploughings and cross-ploughings. Each ploughing was followed by laddering to have a good puddled field. All kinds of weeds and residues of previous crop were removed from the field. The field layout was made on 07 August, 2010 e

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according to design immediately after the final land preparation. Individual plots were cleaned and finally leveled with the help of a wooden plank.

3.10 Fertilizer management

At the time of first ploughing cowdung at the rate of 10 t ha was applied. The experimental plots were fertilized a day before transplanting with 100, 50.

62.5, 10 kg hi' in the form of triple superphosphate (TSP), muriate of potash (MP), gypsum and zinc sulphate respectively, according to the recommended dose of BARC (1989). Urea was top-dressed @ 58 kg N hi' in three equal splits at 10, 30 and 50 days after transplanting (DAT). The entire amounts of J5p MP, gypsum and zinc sulphate were applied at the final land preparation as basal doses.

3.11 Experimental treatments

Two sets of treatments included in the experiment were as follows:

A. Variety (5)

V, = BRRI dhan49 V2 = BRRI hybrid dhan2 V3 = Heera2

V4 Tia V5 = Aloron

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B. Seedling(s) number per hill (3) S1 = I seedling

S2 = 2 seedlings S3 = 3 seedlings 3.12 Experimental design

The experiment was laid out in a factorial randomized complete block design with three replications. There were 45 unit plots in the experiment. Each replication was divided into 15 unit plots where the treatment combinations were allocated at random. The size of each unit plot was 4.0 in x 2.5 m (10 m2).

The spacing between block to block and plot to plot was 1.0 m and 0.5 m.

respectively.

3.13 Uprooting and transplanting of seedlings

Thirty days old seedlings were uprooted carefully and were kept in soft mud in shade. The seed beds were made wet by application of water in the previous day, before uprooting the seedlings to minimize mechanical injury of roots.

Seedlings were then transplanted as per experimental treatment on the well puddle plots on 11 August, 2010. In each plot, there were 16 rows, each row containing 16 hills of rice seedlings (the spacing between row to row and plant to plant was 25 cm and 15 cm respectively). There were a total of 256 hills in each plot.

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3.14 intercultural operations

3.14.1 Gap filling

After one week of transplanting, a minor gap filling was done where it was necessary using the seedling from the same source.

3.14.2 Weeding

During plant growth period two hand weeding were done, first weeding was done at 23 DAT (days after transplanting) followed by second weeding at 38 DAT.

3.14.3 Application of irrigation water

irrigation water was added to each plot according to the critical stage of crop.

Irrigation was done up to 5 cm.

3.14.4 Method of water application

The experimental plots were irrigated through irrigation channels. Centimeter marked sticks were installed in each plot which were used to measure depth of irrigation water.

3.14.5 Plant protection measures

- Plants were infested with rice stem borer and leaf hopper to some extent which was successfully controlled by applying of Diazinone 60 BC on 29 August and

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23 September, 2010. The crop was protected from birds during the grain filling period.

- 3.15 General observation of the experimental field

The field was investigated time to time to detect visual difference among the treatment and any kind of infestation by weeds, insects and diseases so that considerable losses by pest should be minimized. The field looked nice with normal green plants. Incidence of stem borer, green leaf hopper and leaf roller were observed during tittering stage. Bacterial or fUngal disease was not observed.

3.16 Harvesting and post harvest operations

Maturity of crop was determined when 90% of the grains become golden yellow in color. The harvesting was done on 4 m2 of land from every plot. Each plot was separately harvested, bundled, tagged, then brought to the threshing floor. Threshing was done by a pedal thresher. The grains were cleaned and sun-dried to moisture content of 12%. Straw was also sun-dried.

3.17 Recording of data

Data were collected in tillering, panicle initiation, booting, flowering and harvesting stages on the following parameters:

A. Crop growth characters Plant height (cm) Number of tillers per

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Dry weight of leaves (g) Dry weight of stem (g) Dry weight of panicle (g) Chlorophyll content (mg/g) Panicle length (cm)

B. Yield contributing characters

Number of effective tillers per m2

Number of fertile spikelets (filled grains) per Number of sterile spikelets (unfilled grains) per Weight of 1000- grain (g)

-- C. Yield

Grain yield (t ha') Straw yield (t had ) Biological yield (t hi') 1-larvest index (%)

3.18 Experimental measurements

Experimental data collection was started at tillering stage and continued till - harvest. The necessary data were collected from eight selected hills from each

plot.

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Plant height

Plant height was measured at tillering stage, panicle initiation stage, booting stage, flowering stage and harvesting stage. The height of the plant was determined by measuring the distance from the soil surface to the tip of the leaf before heading, and to the tip of panicle after heading.

Number of tillers per

Number of tillers hil1' were counted at tillering stage, panicle initiation stage, booting stage, flowering stage and harvesting stage from prc selected hills and finally averaged as their number hilr'. Only those tillers having three or more leaves at the time of counting were considered.

S Leaf area

Leaf area hilr' was measured by an automatic leaf area meter (Model: LICOR 3000, USA).

Dry matter weight of different parts (leaves, stem, panicle) of plant

Two hills per plot were uprooted at different stages. They were differentiated into leaves, stem, panicle. Then they were oven-dried, from which the weight of leaves, stem, panicle were recorded.

Panicle length

Measurement of panicle length was taken from basal node of the rachis to apex of each panicle. Each observation was composed of an average of 10 panicles.

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Chlorophyll content (mg/g)

Chlorophyll content of leaf at flag leaf was determined on fresh weight basis

a

using the method proposed by Witham et at (1986). Hundred milligram of rice leaf sample was cut into small pieces and dipped into 80% acetone in a twenty five mililiter vial. The vial was made up to the volume with 80% acetone. Then the sample was kept over 48 hours in a dark place. Finally the absorbance of the liltrate was taken by spectrophotometer at 663 nm and 645 nm.

respectively.

Amount of chlorophyll were calculated using the following equations/formula:

Chlorophyll a (mg/g) = [I 2.7(0D663

) -

2.69(0D645 )V/1 000W Chlorophyll b (mg/g) = [22.9(0D645

) -

4.68(OD 3 )V/l000W Chlorophyll a+b (mg/g) = [20.2(OD 5

) -

8.02(OD663)V/l000W Where.

OD = Optical density regarding of the chlorophyll extract at the specific indicated wavelength (645 and 663 nm)

V = Final volume of the 80% acetone chlorophyll extract (ml) W = Fresh weight in gram of the tissue extracted

Number of tillers per

At first, tillers were counted from 8 hills. Then it was converted for 1 m2 area.

Number of fertile spikelets (filled grains) per

Spikelet was considered to be fertile if any kernel was present there. The

a

number of total fertile spikelets present on each panicle was recorded. Then it was converted for 1 m2 area.

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Number of sterile spikelets (unfilled grains) per panicle

Sterile spikelet means the absence of any kernel inside and such spikelets present on each panicle were counted. Then it was converted for I m2 area.

Filled grain %

It was calculated with following formula:

Fertile spikelets

Filled grain % = 100

Total number of spikelets Weight of 1000-grain

One thousand cleaned dried seeds were counted randomly from each sample and weighed by using a digital electric balance at the stage the grain retained 12% moisture and the mean weight were expressed in gram.

Grain yield

Grain yield was determined from 1 m2 of land from each plot and expressed as t ha' on 12% moisture basis. Grain moisture content was measured by using a digital moisture tester.

Straw yield

Straw yield was determined from 1 m2 of land from each plot. After threshing, the sub-sample was oven dried to a constant weight and finally converted to ton per hectare (t ha').

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Biological yield

The biological yield was calculated with the following formula:

Biological yield = Grain yield + Straw yield Harvest index (%)

It denotes the ratio of economic yield to biological yield and was calculated with the following formula:

Grain yield

Harvest index (%) = 100

Grain yield + Straw yield 3.19 Analysis of data

The data collected on different parameters were statistically analyzed to obtain the level of significance using the MSTAT-C computer package program. The mean differences among the treatments were compared by least significant difference (LSD) test at 5% level of significance.

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