Mehri Saeedinia; Seyed Hamzeh Hosseinian; Farhad Beiranvand; Ali Heydar Nasrollahi
Abstract
Considering the great value of water, irrigation scheduling, and cultivation of medicinal plants, this research was conducted at the Faculty of Agriculture, Lorestan University, with the aim of scheduling irrigation of summer savory using CWSI and applying different levels of water stress under the condition ...
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Considering the great value of water, irrigation scheduling, and cultivation of medicinal plants, this research was conducted at the Faculty of Agriculture, Lorestan University, with the aim of scheduling irrigation of summer savory using CWSI and applying different levels of water stress under the condition of pot planting. In this research, seeds of summer savory were cultivated with three replications under four irrigation treatments of 100%, 80%, 60%, and 40% of readily available water (RAW) (IR100, IR80, IR60 and IR40). Irrigation of the control treatment (IR100) was carried out when all the soil RAW was depleted. Irrigation of the other three treatments was carried out at the same time but with, respectively, 80%, 60%, and 40 percent of the volume applied to IR100. The canopy cover temperature in IR100 and air temperature (dry and wet) were measured on the day after (8-14 o’clock) and before irrigation (12-15 o’clock) in order to construct the lower and upper limits base lines required to calculate CWSI. According to the result, the upper base line equation is (𝑇𝑐-𝑇𝑎) UL = 0.69, and the lower base line is (𝑇𝑐-𝑇𝑎) LL = 0.2787 - 0.1134 (VPD). Result showed that the effect of water stress on yield was significant. The highest yield was observed in IR100 (1.756 g / plant) and the lowest yield was observed in IR40 (1.421 g / plant). The crop water stress index (CWSI) of the four treatments in the day before irrigation was 0.19, 0.21, 0.28, and 0.46, respectively. According to this information, the permissible CWSI index for irrigation scheduling of summer savory growing in pots was 0.19. The result of means comparison indicated that differences between IR100 and IR80 in values of CWSI and canopy cover temperature were not significant, but they were significant between IR100, IR60 and IR40. The increment of CWSI in IR80, IR60 and IR40 were 10%, 47%, and 142 percent relative to the IR100. In this research, a strong correlation (r= -0.978*) was obtained between CWSI and stomatal conductance.
m s; s b; b a
Abstract
In this research, the amount of maize yield was simulated under condition of different water salinities and climate change scenarios in Ahvaz region. Combined CSIRO-MK3.5 model and emission scenarios A1B, A2, and B1 were used as future (2021-2050 and 2070-2100) climate change scenarios (considering ...
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In this research, the amount of maize yield was simulated under condition of different water salinities and climate change scenarios in Ahvaz region. Combined CSIRO-MK3.5 model and emission scenarios A1B, A2, and B1 were used as future (2021-2050 and 2070-2100) climate change scenarios (considering 1981-2010 as reference period). Additionally, AquaCrop model was used to predict the impact of climate change scenarios on maize yield under conditions of five salinity treatments including: (S0: Karoon river water (salinity: 2.3 dS/m); S1 (salinity: 3.5 dS/m), S2 (salinity: 4.5 dS/m); S3(salinity: 5.5 dS/m); and S4 (salinity: 6.5 dS /m). In order to show the impact of climate change alone, the amount of yield for each salinity treatment under different scenarios was compared with the same treatments yield under the reference scenario. Results showed that in the 2021-2050 period, the difference between maize yields for different scenarios was negligible compared to the reference scenario. However, in the 2070-2100 period, yield reduction under A1B scenario was %15, under B1 scenario 24%, and under A2 scenario, it was 35 percent. The results of salinity and climate change impacts together showed that, in the first future period, maximum reduction of yield would happen under the S4 B1N1 scenario (37 percent) and for the second future period, it would be under S4A2N2 scenario (58 percent). Finally, it was determined that the trend of yield reduction under salinity treatments was linear in all scenarios.