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Professor Jayashankar Telangana State Agricultural University, Hyderabad (Telangana State)
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ThesisItem Open Access DRIP IRRIGATED MAIZE AND SUNFLOWER: GROWTH, YIELD, EVAPOTRANSPIRATION AND WATER PRODUCTION FUNCTIONS(PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD, 2015) MALAMASURI, KADASIDDAPPA; PRAVEEN RAO, VThe field experiment entitled “Drip irrigated maize and sunflower: growth, yield, evapotranspiration and water production functions” was conducted at the Research and Development (R&D) farm of Water and Land Management Training and Research Institute (WALAMTARI), Himayatsagar, Hyderabad, Telangana, India during rabi season of 2012-13 and 2013-14. Two crops viz., maize and sunflower were tested separately with six irrigation treatments involving five irrigation levels through drip (40%, 60%, 80%, 100% and 120% pan evaporation replenishment) in comparison with one surface furrow irrigation at 1.0 IW/CPE ratio laid out in Randomized Block Design (RBD) with four replications. Surface drip irrigation system used in the study consisted of 16 mm integral dripper line laid out on the ground surface along the crop rows at 1.20 m and 0.90 m apart for maize and sunflower, respectively with emitters spaced at 0.40 m on laterals having discharge capacity of 4 LPH. The application rate was adjusted as per the treatments. Growth parameters viz., plant height, number of functional leaves plant-1, leaf area index, dry matter production; Crop Growth Rate (CGR), Leaf Area Duration (LAD), Biomass Duration (BMD), Relative Growth Rate (RGR) and Net Assimilation Rate (NAR) were measured/determined at periodical intervals (At 15 DAS and then onwards at every 30 days intervals) for maize and sunflower crops. Likewise, yield attributes viz., number of cobs plant-1, cob length, number of grain rows cob-1, number of grains cob-1 for maize and capitulum diameter, total number of seeds capitulum-1, percentage of filled and unfilled seeds capitulum-1 for sunflower and test weight, grain/seed yield, total dry matter yield and harvest index were measured at harvest for both the crops. Nutrient (NPK) uptake was estimated at different crop growth stages, and at harvest and expressed as total NPK uptake. Water use studies include daily pan evaporation data, irrigation water applied and periodical monitoring of soil moisture. From the water use data seasonal crop evapotranspiration, water productivity, crop coefficient, water production functions, optimization of water and economic ramification were generated. Weather elements viz., temperature, relative humidity, rainfall and rainy days, sunshine hours and wind velocity were also measured during the crop growing seasons. The data generated on various aspects in this study on effect of irrigation levels on maize and sunflower were analyzed through standard statistical methods and logical conclusions were drawn. Drip irrigation scheduled at 100% pan evaporation replenishment (Epan) recorded significantly higher growth parameters, yield attributes, grain/seed and total dry matter yield over drip irrigation scheduled at 40%, 60% Epan and surface furrow irrigation at 1.0 IW/CPE ratio. However, the drip irrigation scheduled at 100% Epan was at par with the 80% and 120% Epan in respect to all the parameters signifying the importance of frequent application of optimum or suboptimum amount of water in root zone of crop to maintain good soil moisture favourable to plant growth. Regression relationships between soil moisture versus growth and yield parameters were highly significant and associated to one another indicating the importance of adequate soil moisture throughout the crop growth periods in both the crops. Grain yield was found to be significantly and positively correlated to growth viz., plant height (R2 = 0.977**), number of functional leaves plant-1 (R2 = 0.933**), leaf area index (R2 = 0.903**) and dry matter production (R2 = 0.965**); and yield components viz., cob length (R2 = 0.878*), number of grain rows cob-1 (R2 = 0.931**), number of grains cob-1 (R2 = 0.977**), test weight (R2 = 0.984*) for maize. Sunflower seed yield was also found to be significantly and positively correlated to growth viz., number of functional leaves plant-1 (R2 = 0.946**), leaf area index (R2 = 0.994**) and dry matter production (R2 = 0.993**); and yield components viz., capitulum diameter (R2 = 0.924*), total number of seeds capitulum-1 (R2 = 0.999**), % of filled seeds capitulum-1 (R2 = 0.936**), test weight (R2 = 0.971**) and harvest index (R2 = 0.967**). Similarly, correlation studies between growth and yield traits and yield were also showed significant and positive association between themselves in both the crops. Significantly highest oil content (43.0% and 42.1% during 2012-13 and 2013- 14, respectively) and oil yields (1195.0 kg ha-1 and 1124.8 kg ha-1during 2012-13 and 2013-14, respectively) in sunflower were obtained when irrigation was scheduled at 100% Epan through drip system. Similarly, significantly highest nutrients (NPK) uptake was recorded with drip irrigation scheduled at 100% Epan compared with the rest of the treatments in both the years in both the crops. Water deficits (Crop ET deficit) at different crop growth period of maize and sunflower (40% Epan and 60% Epan) caused significant reduction in grain/seed yield. The yield reduction in stress treatments varied from 171.66% to 38.90% in maize and 137.24% to 40.36% in sunflower relative to 80% Epan treatment on pooled basis. The reduction in yield observed was due to contemporaneous reduction in growth and yield traits in these treatments. Similarly, the extent of reduction in yield due to surface irrigation was to the tune of 40.86% and 36.84% lower than 100% Epan and 80% Epan, respectively in maize and 82.80% and 77.97% lower than 100% Epan and 80% Epan, respectively in sunflower. The highest seasonal crop ET (421.7 mm and 343.0 mm in maize and sunflower, respectively) and crop ET rates (3.61 and 2.94 mm day-1 in maize and sunflower, respectively) were recorded in surface furrow irrigation treatment than rest of the drip irrigation treatments. Among the drip irrigation, 120% Epan treatment wherein the seasonal crop ET was 382.3 mm and crop ET rate of 3.27 mm day-1 in maize and 312.7 mm and 2.68 mm day-1 in sunflower were the highest compared to remaining drip treatments. Water productivity in both maize and sunflower was significantly higher in deficit irrigation treatment viz., drip irrigation at 80% pan evaporation replacement compared to rest of the treatments owing to on par yield relative to 100% Epan treatment. The crop ET was significantly (P = 0.01) and positively correlated to LAI and LAD in both the crops. The regression of crop evapotranspiration on reference crop evapotranspiration showed significant and positive correlation with coefficient of determination (R2) of 0.895**. 0.685* and 0.826* for maize and 0.961**, 0.854* and 0.928** for sunflower during 2012-13, 2013-14 and on pooled basis, respectively. Crop coefficient (ETc/ETo) was highest with surface furrow irrigation at all the crop growth stages in both the crops. Optimum crop coefficient was registered with drip irrigation at 80% Epan. Further this (80% Epan) was the treatment wherein optimum yield production was observed and Kc values recorded at this treatment were close to FAO Kc values. Maize crop net irrigation requirement ranged between 21.42 to 98.42 mm at different crop growth stages with seasonal requirement of 311.81 mm and the peak gross irrigation requirement at source point amounted to 1093.50 m3. In case of sunflower, the net irrigation requirement ranged between 20.5 mm to 102.3 mm at different crop growth stages with seasonal requirement of 248.4 mm and the peak gross irrigation requirement at source point amounted to 1136.8 m3. Among all the production functions, the seasonal water production function expressed by quadratic or second order polynomial for both grain/seed yield and dry matter yield in both maize and sunflower crops were found to be statistically good enough with regard to fitting of the measured data and F-value for testing R2 were highly significant at P = 0.01. The predicted maximum grain yield of maize was 8565 kg ha-1 during 2012-13 with crop ET of 388.1 mm and 8092 kg ha-1 during 2013-14 with crop ET of 317.1 mm beyond which the yield decrease. The quantity of irrigation water that is economically optimum level (Economic optima) which will maximize the net return under prevailing market prices (` 13.0 kg-1) worked out to be 352.4 ha-mm with the resultant grain yield of 8303 kg ha-1. In case of sunflower, the predicted maximum seed yield was 2821 and 2843 with crop ET of 305.9 mm and 270.3 mm during 2012-13, 2013-14, respectively and the economic optima with net return under prevailing market prices (` 35.0 kg-1) worked out to be 288.3 ha-mm with the resultant seed yield of 2845 kg ha-1. At lower levels of crop ET, maximum profit of sunflower can be achieved when compared to maize. However, in terms of tonnage, maize out yielded sunflower at all seasonal water supply levels through drip. But the cost of the produce play very important role for the final profit, which in turn depends on selection of the crop, available resources and prevailing weather conditions during crop growth period.