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Effect of Zeolite and Irrigation Frequency on Barley Using Sub-Surface Dripper in Hot Environment
Ahmed Al-Busaidi, Tahei Yamamoto1 and Torahiko Tanigawa2 College of Agricultural & Marine Sciences, Sultan Qaboos University,
P.O. Box 34, Al-Khod 123, Oman, 1Arid Land Research Center, Tottori University 1390 Hamasaka, Tottori 680-0001, Japan, and
2College of Agriculture, Osaka Prefecture University, 1-1 Gakuencho, Sakai, Osaka 599-8531, Japan
Abstract. Water stress is the main environmental factor limiting cereal yield in Mediterranean environment where barley (Hordeum vulgare L.) is one of the main crops. This investigation was aimed to evaluate the effects of zeolite and water stress on barley growth under irrigation of modified sub-surface dripper and heat stress. A sand dune soil was amended with Ca-type zeolite and irrigated every 2nd, 3rd, 4th and 5th day basis. The results showed that zeolite application significantly increased water holding capacity of the soil and improved plant growth compared to the un-amended control. Using sub-surface irrigation with zeolite amendment helped the plants to use water efficiently, reduce water evaporation, keep much water in lower horizons, encourage leaching process and enhance plant growth. Plant parameters showed significant differences among treatments and affected negatively by heat and water stress conditions. High temperature caused acceleration in evapotranspiration, water stress in plants and depletion of water from the root zone. The temperature in the greenhouse caused substantial water loss and induced water deficit situation in plants. A better plant growth was noticed with zeolite treatment as compared to control. Using sub-surface irrigation remained an excellent choice for the reduction of evaporation and achieving higher water use efficiency. Application of zeolite together with subsurface irrigation may provide a favorable condition for crop production in water scarce areas.
1. Introduction
Fresh water resources are essentially finite on earth, and the development of additional supplies for human use is increasingly limited due to economic and ecological reason. This situation emphasizes the need for an efficient use of the water to cope with the growing water scarcity (Theodore, et al., 2007). Moreover, drought and temperature are major limiting factors in crop production because they affect almost all plant functions (Beemarao, et al., 2007). Under elevated temperature, plant could be water stressed due to the higher evapotranspiration. High temperatures cause an array of morpho-anatomical, physiological and biochemical changes in plants, which affect plant growth and development and may lead to a drastic reduction in economic yield.
Major impact of high temperatures on shoot growth is a severe reduction in the first internode length resulting in premature death of plants (Hall, 1992). However, heat stress is a complex function of intensity, duration, and rate of increase in temperature. The extent to which it occurs in specific climatic zones depends on the probability and period of high temperatures occurring during the day and/or the night.
Water stress limits grain yield in many crops including cereals (Abdul Wahid and Shabbir, 2005). Barley (Hordeum vulgare L.) is regarded an important cereal grown in many countries of the world. It is the main cereal of arid and semiarid climates due to its lower water demand when compared to other crops. However, barley yield is also impaired by water and heat stress conditions. The productivity of barley is reported to be limited by terminal water stress and high temperatures during grain filling (Agueda, et al., 1999). Blum (1989) found a reduced growth of barley plants due to drought stress. Agueda, et al. (1999) reported that the regulation of leaf transpiration by stomatal closure may act as a mechanism of drought resistance. Matin, et al. (1989) reported a positive correlation between diffusion resistance in barley leaves and drought tolerance. The quality and quantity of plant growth depends on cell division, enlargement and differentiation which are affected by water stress (Manivannan, et al., 2007).
To improve the barley crop production under adverse conditions, application of fertilizers or growth promoters seems to be imperative.
Applying amendment to the soil could decrease the adverse effects of water and heat stresses and promote plant growth. Synthetic zeolite produced from the coal ash is being considered as beneficial soil amendment since it
enhances the retention of plant nutrient, regulates water supply and supplements micronutrients (Ayan, et al., 2005). The zeolitic material, in addition to the buffering capacity, possesses an important exchange capacity that could reduce the soluble metal concentration and eliminate the pollution in the leaching. Vassilis and Inglezakis (2005) also reported that zeolites were used in ion-exchange applications in soil solution and used for the removal of heavy metals from the wastewaters. The improvement in growth with zeolite may also be related to the essential nutrients contained in zeolite. Ayan, et al.
(2005) reported increased cation exchange ability, water retention and plant nutrients following zeolite application. Moreover, it was approved by Al- Busaidi, et al. (2008) that soil amendment with zeolite could effectively ameliorate salinity stress and improve nutrient balance in sandy soil.
Improvement in the management of agricultural water is highly required to conserve water, energy and soil while satisfying society’s increasing demand for food and fiber, livestock, and forest products (Kassam, et al., 2007). Understanding the effect of high temperature on barley is an important issue for its quality improvement. Evaluating a modified type of subsurface irrigation system in zeolite amended sandy soil under water stress condition could be beneficial for better barley production. Therefore, the objective of this study was to investigate the effect of zeolite and water stress on barley growth under sub-surface drip irrigation in a hot greenhouse environment.
2. Materials and Methods
The experiment was carried out at Arid Land Research Center of Tottori University Japan in a greenhouse. Sand dune soil was used for the study and the relevant properties are shown in Table 1. Soil texture was determined by the pipette method (Gee and Bauder, 1986). Exchangeable cations were leached from the soil with neutral ammonium acetate and their concentrations were determined using an atomic absorption spectrophotometer (Model Z-2300 Hitachi Corp, Japan). Electrical conductivity and pH in soil: water suspension of 1: 5 were also measured with pH and EC meters (Accumut M-10 and Horiba DS-14), respectively. Other physicochemical properties were analyzed following Klute (1986) methods.
Table 1. Selected physicochemical characteristics of soil.
Property Value
EC (1: 5) water 0.03 dS m-1
pH 6.36
Exchangeable K+ 0.06 cmolc kg-1
Exchangeable Ca2+ 0.34 cmolc kg-1
Exchangeable Mg2+ 0.45 cmolc kg-1
Exchangeable Na+ 0.10 cmolc kg-1
Cation exchange capacity 2.40 cmolc kg-1
Bulk density 1.5 g cm-3
Infiltration rate (intake rate) 30.0 mm min-1 Saturated hydraulic conductivity 0.007 cm sec-1
Field capacity (pF1.8) 6 %
Permanent wilting point (pF4.2) 2 %
Texture Sand
The experiment was conducted in plots of 1 m2. Eight plots were used for 2, 3, 4, and 5 days irrigation intervals with zeolite and control treatments. Each treatment had four growing points (Fig. 1). Synthetic Ca-type zeolite was applied at the rate of 2% (equivalent to 2 kg m-2).
Barley was used as test crop and irrigated by modified sub-surface irrigation system (Fig. 1). The system was made of cylindrical tube with floating valve. It was inserted in the soil up to 10 cm depth. The system was connected with 18 liters tank and the slow release of water was regulated by a floating valve. The amount of the water released from the valve depended on the moisture content of soil around the system. Crop was irrigated intervally after every 2nd, 3rd, 4th, and 5th day. The irrigation tank was filled at the day of irrigation and a basal dose of fertilizer containing 180 kg N ha-1,45 kg P ha-1 and 80 kg K ha-1 was added in the irrigation water. Evaporation was monitored by placing two evaporation pans (class A) inside the plots. A portable wet sensor was used to monitor soil temperature, water content and salinity at 0-10 cm soil depth. Climatic conditions such as air temperature and relative humidity were monitored continuously day and night by Hobo meter (Pro series, onset, USA).
Fig. 1 Field experiment with sub-surface irrigation of new dripper.
Prior to the plants harvesting for their fresh and dry weights, plant height and leaf area (using portable area meter LI-3000A) were measured. The dry biomass was estimated after drying shoots in an oven at 65oC for 48 h. Data were analyzed statistically for the analysis of variance (ANOVA) and the means were compared at probability level of 5 % using least significant difference (LSD) test.
3. Results and Discussion
3.1 Growth Condition
During the study, climatic conditions in the greenhouse were varied with average temperature of 30 oC and relative humidity of 70 %. It can be seen from Fig. 2 that air temperature remained very high (>40oC) up to several days which created a negative impact on plant growth. Water loss from the evaporation pan was directly related to the prevailing environmental conditions in the greenhouse. As can be seen from Fig. 3 the pan evaporation varied with time (4-9 mm/day) with average value of 6 mm/day. Higher air temperature led to several changes in the plant growth parameters. Soil temperature (Fig. 4) was recorded high in some treatments (>30oC). Highest soil temperature value was found in control soil irrigated at 5 days interval, whereas the lowest was noted in control soil receiving 2nd day irrigation. Zeoilte application retained much water as compared to un-amended sandy soil (Fig. 5).
Fig. 2. Meteorological data during study.
Fig. 3. Water evaporation as affected by environmental conditions.
Fig. 4. Soil temperature as affected by metrological data and different treatments (symbols of 2-5, C and Z represent irrigation intervals, Control and Zeolite treatments, respectively).
0 2 4 6 8 10
5-May 10-May 15-May 20-May 25-May 30-May 4-Jun 9-Jun 14-Jun 19-Jun Time (day)
Evaporation (mm/day)
Fig. 5. Water content recorded by wet sensor at 0-10 cm depth.
The use of water was also related with the plant growth. The extra water which was accumulated in small pores of zeolite was used by the intensive growth of plants in zeolite treatment.
Using wet sensor could predict surface water content within 0-10 cm depth but deeper horizons values could be completely different from the surface. However, these reasons or expectations can be clarified much better when related to plant growth parameters. Generally and under field conditions, high temperature stress is frequently associated with reduced water availability (Simoes-Araujo, et al., 2003). Usually fresh water used for irrigation does not possess any problem of soil salinity. However, there was a variation in soil salinity among different treatments (Fig. 6).
For example control soil irrigated at different intervals produced high values of soil salinity as compared to the zeolite amended soil. This situation could cause low soil temperature in control soil since this soil was losing greater water than zeolite treated soil and maintained the soil in cool condition. The zeolite applied soil got lower values of salinity due to the higher water holding capacity which also supported leaching
0 1 2 3 4
28-May 2-Jun 7-Jun 12-Jun 17-Jun
Time (day)
Soil moisture (%)
2C 3C 2Z 3Z
0 1 2 3 4 5
28-May 2-Jun 7-Jun 12-Jun 17-Jun
Time (day)
Soil moisture (%)
4C 5C 4Z 5Z
process. Using sub-surface irrigation with zeolite amendment helped in reducing evaporation, and kept much water in the lower soil horizons, and thus positively affected plant growth. Surface irrigation evaporates much water than subsurface and ultimately plant growth and irrigation requirements differ accordingly. Applying zeolite with sub-surface irrigation should give the best data among all other treatments but unfortunately high value of temperature was covering all these advantages and suppressed plant growth. It was reported by Abdul Wahid and Shabbir (2005) that heat stress is a major growth limiting factor for most crop plants. Plant parts including leaves, flower buds and roots are all affected by it. Whereas, water deficit or osmotic effects are probably the major physiological mechanisms for growth reduction as both stresses lower the soil water potential. Drought reduces both nutrient uptake by the roots and transport from the roots to the shoots, because of restricted transpiration rates and impaired active transport and membrane permeability (Hu and Schmidhalter, 2005). The decline in soil moisture also results in a decrease in the diffusion rate of nutrients in the soil to the absorbing root surface (Alam, 1999).
Fig. 6. Soil salinity as monitored by wet sensor.
0 0.1 0.2 0.3 0.4
28-May 2-Jun 7-Jun 12-Jun 17-Jun
Time (day)
Soil salinity (dS/m)
2C 3C 2Z 3Z
0 0.1 0.2 0.3 0.4 0.5 0.6
28-May 2-Jun 7-Jun 12-Jun 17-Jun
Time (day)
Soil salinity (dS/m)
4C 5C 4Z 5Z
3.2 Plant Growth
As a result of water stress and zeolite treatments plant growth varied among treatments (Table 2). Grain number, fresh and dry weights are parameters that were affected by different growth conditions. Zeolite treated soil irrigated after 2 days intervals gave the best results in terms of plant biomass whereas control soil irrigated after 5 days intervals produced the lowest crop biomass. While comparing the data among irrigation intervals in zeolite treatment, a huge reduction was found in grain numbers and dry biomass in control irrigated soil (Fig. 7).
Reduction in leaf area by water stress is an important cause of reduced crop yield through reduction in photosynthesis.
Table 2. Plant growth parameters as affected by zeolite and irrigation intervals.
Treatment
Height Leaf area Grain
Fresh weight
Dry biomass Zeolite
treatment
Irrigation interval
(day) cm cm2 NO. g g
Control
2 65.00ba 24.11cbd 78b 464.00dc 117.80ba
3 61.67cb 27.39ab 31f 519.50ba 96.97dc
4 54.33e 18.18feh 31f 319.87fe 67.23feg
5 47.67f 15.82hg 38de 150.47h 40.90h
Zeolite 2
67.67ab 26.50bac 87a 464.03cd 125.83ab 3 60.00dc 22.44de 50c 522.90ab 104.77cd 4 54.33e 19.53ed 36edf 323.50ef 70.97ef 5 49.33f 16.58gefh 50c 205.93g 60.53gef
*Means in the column with same letter indicate no difference at Duncan’s Multiple Range Test at P < 0.05.
Fig. 7. Reduction in control plant parameters compared to zeolite treatment.
-30 -20 -10 0 10 20 30 40 50
2 3 4 5
Irrigation intervals (day)
Reduction (%)
Height LA Grain NO FW DW
However, leaf water potential, osmotic potential and relative water content decreased in stressed plants at all growth stages (Kramer, 1983).
Leaf area plasticity is important to maintain control of water use in crops.
The number of leaves per plant and individual leaf size and leaf longevity reduced by decreasing soil water potential, leaf area expansion depends on leaf turgor, temperature and assimilate supply for growth, which are all affected by drought (Pessarakli, 1994). The reduction in plant height might be associated with declined cell enlargement and cell growth due to the low turgor pressure and also more leaf senescence under drought stress. The fresh weight decreased under drought condition might be the reason for suppression of cell expansion and cell growth due to the low turgor pressure. Whereas, decreased total dry weight may be due to the considerable decrease in plant growth, photosynthesis and canopy structure (Beemarao, et al., 2007).
Good environment with zeolite treatment supported plant growth and helped plant to produce more tillers. The increment in plant growth and higher yield caused higher water consumption by the plant as compared to control (Fig. 8). Moreover, high temperature created greater evapotranspiration and thus higher quantity of water was depleted from the root zone. The temperature conditions of greenhouse caused substantial water loss and induced water deficit situation in plants which is confirming the finding of Al-Busaidi, et al. (2007). Sule, et al. (2004) reported severe effects of heat stress on cereals in several countries.
Maximum number of tillers and the highest dry matter were produced when the root temperature was at the intermediate levels of 15 to 20 °C.
Moreover, heat stress, singly or in combination with drought, is a common constraint during anthesis and grain filling stages in many cereal crops of temperate regions (Guilioni, et al., 2003).
Fig. 8. Water deficit in zeolite treatment compared to control.
0.5 0.8 1.1 1.4 1.7 2 2.3 2.6
2 3 4 5
Irrigation interval (day)
Water deficit (%)
This study also confirmed that growth environments differentiated the performance of barley under the same type of irrigation water. Sule, et al. (2004) reported that high temperature is one of the environmental stress factors that can affect the growth and quality characteristics of barley. Moreover, it was found by Macnicol, et al. (1993) that both water and heat stress reduced yield and grain size of barley. Plants tend to maintain stable tissue water status regardless of temperature when moisture is ample; however, high temperatures severely impair this tendency when water is limiting (Machado and Paulsen, 2001).
Using modified sub-surface irrigation system was helping plants to increase the efficiency of the applied water. Water productivity factor can be calculated by comparing water used in this study with plant production under each treatment. From Fig. 9 and by using fresh weight for the comparison, it can be seen that 3 days irrigation intervals was giving the best result followed by 4 days intervals. In both treatments of control and zeolite, the values were similar but zeolite treatment was a little bit higher.
Fig. 9. Water productivity with fresh and dry weights.
0 0.5 1 1.5 2 2.5 3
2C 3C 4C 5C 2Z 3Z 4Z 5Z
Growth condition Water productivity (Kg m-3)
0 0.1 0.2 0.3 0.4 0.5 0.6
2C 3C 4C 5C 2Z 3Z 4Z 5Z
Growth condition Water productivity (Kg m-3)
Fresh weight
Dry weight
However, checking water productivity with plant dry weight, 3 and 4 days irrigation intervals were giving the best data but in this case zeolite treatment was clearly higher than control. The high value of water productivity of 5 days zeolite treatment was unexpected but this is a good sing that both zeolite and sub-surface irrigation were efficiently used. It is clear that incorporation work of new irrigation system with zeolite and under heat stress condition was supporting plant growth with minimum water supply (Fig. 9). Singh and Kumar (1981) found that barley showed higher water-use efficiency with one irrigation at the active tillering stage as compared to two irrigations and no water stress conditions. Higher water use efficiency of barley over wheat under identical water stress was observed by Sinha (1972), but his observations are not sufficient to come to a final conclusion with respect to water resource utilization and crop planning. Supplying full water requirements to some tree crops and vines may not be the best irrigation strategy in many situations, and there is growing evidence that adoption of regulated deficit irrigation practices would lead to higher water productivity while maintaining or increasing farm income. A considerable increase in the water use efficiency of wheat and barley by scheduling irrigations at critical growth stages was observed. These results are contrary to those of Singh and Kumar (1981) on wheat. They reported the higher water use efficiency with higher water use under severe to mild stress treatments.
Analyzing different effects of water stress conditions and zeolite treatments on soil and plant parameters, revealed that surface soil parameters such as soil temperature and moisture content was not significantly different with all applied treatments. Whereas, plant parameters were showing a significant difference between studied treatments (Table 3). Going deeper in the effect of each treatment on soil and plant parameters, we found that two-way analysis of variance confirming the result found by ANOVA test for soil parameters (Table 4). Whereas, it is showing unexpected data for zeolite application. The data is not significantly different among plant growth parameters except grain number. Moreover, the interaction effect of both treatments was also not significantly different with soil and plant parameters.
Table 3. Analysis of variance (ANOVA) for soil and plant parameters.
Sig. * Mean F
Square df
Sum of Squares Parameter
0.856 0.450
1.060 7
7.419 Soil moisture
0.998 0.095
1.429 7
10.004 Soil
temperature
0.000 9.977
157.143 7
1100.000 Plant height
0.000 11.148
59.368 7
415.577 Leaf area
0.000 10.372
1373.899 7
9617.292 Grain No.
0.000 12.193
61363.83 7 4
429546.838 Fresh weight
0.000 10.650
2712.864 7
18990.045 Dry biomass
* level of significance at P < 0.05.
The good explanation/reason for this finding that plant grew under zeolite treatment was better than control but high consumption of water was keeping plant under some water stress conditions. Reduction in air temperature will support plant to keep much water and survive longer time. Zeolite treatment was enhancing plant growth by supplying much water and nutrients to the plant. That was shown by differences in plant yield between control and zeolite treatments. Generally, if plant grown under good temperature, it will give much better growth with zeolite treatment compare to control. Moreover, using sub-surface irrigation will be much better in economizing water and irrigation efficiency if the growth temperature is not very high.
Table 4. Summary of two-way analysis of variance on irrigation interval and zeolite effect of selected soil and plant parameters.
Z
× I Zeolite (Z)
Irrigation interval (I) Parameter
P-value*
NS NS
NS Soil moisture
NS NS
NS Soil temperature
NS NS
0.0001*
Plant height
NS NS
0.0001*
Leaf area
NS 0.0292
0.0001*
Grain No.
NS NS
0.0001*
Fresh weight
NS NS
0.0001*
Dry biomass
* denotes the level of significance at P value < 0.05 and NS denotes non-significance.
Finally, understanding plant responses to drought is of great importance and also fundamental parts for making the crops stress tolerant. Chemical treatment and agronomical crop management practices have been tried to alleviate the water deficit effects.
Supplementing the medium with Ca2+ alleviates growth inhibition by salt in glycophyte plants (Abdul Jaleel, et al., 2007).
4. Conclusion
In agricultural systems, plant productivity is strongly influenced by environmental conditions. Yield potential in crops is limited due to different abiotic stresses. Drought and extreme temperatures are considered as the most important ones. Based on the findings of this experiment, it could be concluded that the deleterious effects of water and heat stresses on barley crop in a sandy soil can be reduced with zeolite amendment and use of sub-surface irrigation system. The ability of zeolite to hold water and exchange nutrients gave the plants the required strength to survive longer and give better production than control of sandy soil. The good features of zeolite and with use of modified drippers could be one of the best ways to fight drought problems. Heat and drought can cause a big damage in a place having hot and harsh environment. However, using zeolite supported with economized sub-surface irrigation system could be one of the best ways to get some production from a plant suppose to be dead or can not survive under those conditions. Finally, adopting a proper soil amendment like zeolite with new irrigation system could have beneficial effects on such interactions.
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