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parisa shahinrokhsar; Aslan Egdernezhad
Abstract
Despite Gilan Province being a rainy region in Iran, inappropriate distribution of rainfall during the growing season has a negative impact on the growth of crops, including borage. This study was conducted to determine the proper irrigation regime for borage at different stages of growth. For this purpose, ...
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Despite Gilan Province being a rainy region in Iran, inappropriate distribution of rainfall during the growing season has a negative impact on the growth of crops, including borage. This study was conducted to determine the proper irrigation regime for borage at different stages of growth. For this purpose, fifteen field experiments, based on 15 combinations obtained from the Central Composite Design, were conducted using high and low levels of treatments including water requirement (without irrigation (I1) and full water supply (I2)), two growth stages (stem elongation (D1), stem elongation and flowering (D2)), and two years with different rainfall (drought (Y1) and wet season (Y2)). The experiments were performed in Giulan Agricultural and Natural Resources Research and Education Center located in Rasht. Irrigation and stage of growth had the most and the least effects on borage yield and growth parameters, respectively. Dry season increased the grain yield, oil yield and oil percentage, while other parameters reached their maximum value in wet year. The value of 1000-seed weight for D2 was equal to 18.9 g, and the values of dried flower yield, fresh flower yield, seed yield, and economic yield are equal to 468, 858, 486 and 983 kg.ha-1, respectively. Oil yield and oil percentage for D2 were equal to 160 kg.ha-1 and 33.5%, respectively. Considering the optimal levels for all parameters based on the interpolation of factor values in the central composite design, if the percentage and yield of oil is less important than the other parameters, it is necessary to provide 88% of irrigation water for the stem and flowering stages in the wet season. In order to achieve maximum yield and oil content, full supply of irrigation needs in dry season and in the stem stage should be considered.
p sh; e a; s r; m a
Abstract
Today, even in humid areas, the water crisis is a major problem for agriculture and increasing the efficiency of water use is also one of the requirements for sustainable development. Regarding this, the use of plant growth simulation models as a tool for managing water crisis seems useful. In this study, ...
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Today, even in humid areas, the water crisis is a major problem for agriculture and increasing the efficiency of water use is also one of the requirements for sustainable development. Regarding this, the use of plant growth simulation models as a tool for managing water crisis seems useful. In this study, WOFOST model to simulate the performance of two soybean cultivars (DPX and SEPIDEH) under deficit irrigation was used in the Gorgan region. Using the measured plant yield and simulated water balance components from the model, the average productivity of evapotranspiration (Wp < sub>ET), based on seed yield, was obtained as 0.72 kg m-3. With increasing water stress, water use efficiency based on irrigation and precipitation series (Wp < sub>I+R) and water use efficiency based on irrigation (Wp < sub>I) increased in both cultivars, but the DPX water use efficiency under drought stress was higher than the SEPIDEH cultivar. According to the results and accuracy of WOFOST model, index of relative root mean square errors of seed yield and total biomass in both cultivars was less than 10%, the index of the coefficient of residual mass (CRM) was close to zero, the performance factor (EF) was 0.89, the coefficient of determination (R2) equaled 0.93, and the index of Willmott agreement (IOA) was about 0.89. Overall, based on the findings of this study, favorable performance of the model to simulate the growth process and water impact on soybean seed yield and water efficiency is confirmed and cultivar DPX is recommended for cultivation in the Golestan province.
Parisa Shahinrokhsar; Mohammadsmaeil Asadi
Abstract
Among the main causes of low water use efficiency are use of an improper irrigation method and applying excessive irrigation. To evaluate tape and furrow irrigation methods for soybean cultivation under different irrigation regimes, a field experiment was conducted in two years (2006-2007) at Gorgan ...
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Among the main causes of low water use efficiency are use of an improper irrigation method and applying excessive irrigation. To evaluate tape and furrow irrigation methods for soybean cultivation under different irrigation regimes, a field experiment was conducted in two years (2006-2007) at Gorgan Agricultural Research Station located in Golestan province in north of Iran. The experiment was laid out in a split plot design in the form of completely randomized blocks where each treatment was replicated three times. Irrigation systems of tape and furrow were set up as the main plots, and three irrigation regimes of 100%, 75% and 50% of total crop water requirement were allocated to the subplots. Comparison of water consumption (m3/ha) between the two systems showed that tape irrigation had 33 percent less water use than furrow irrigation. Results indicated that the soybean yield was not affected by irrigation systems. But, the different irrigation regimens had some impact on crop yield. Water use efficiency in the full irrigation (100 %) regime under drip tape irrigation was 1.6 times that of furrow irrigation system. In tape irrigation, mean water distribution uniformity (Ed) in full irrigation was 96% and in furrow irrigation it was 95%. Application efficiency (Ea) under tape irrigation was 84%, which was much higher than furrow irrigation. Also, based on the results, most of water losses in furrow irrigation systems were due to surface run off, while these losses were not observed in the tape irrigation. Overall, in drip tape irrigation, less water was consumed and water use efficiency increased compared to furrow irrigation