علیرضا منعم زاده

The presence of salts in irrigation water and high evapotranspiration rate in Sistan and Baluchestan cause the accumulation of salt in the soil and as a result increases the osmotic force in soil. One method for crop irrigation planning is the use of Idso crop water stress index (CWSI) and Moran water deficit index (WDI). In order to investigate the effect of irrigation water salinity on CWSI and WDI and also wheat irrigation planning, an experiment was performed with three different irrigation water quality in Iranshahr, through the 1398-99 crop year. The experiment was performed as a randomized complete block design with 4 replications and 3 treatments including (1) irrigation water with salinity of 0.7, (2) irrigation water with salinity of 2.5 and (3) irrigation water with salinity of 5.2 dSm-1. The results showed that irrigation water with salinity of 0.7 and 2.5 dSm-1 have no significant difference in terms of yield and water use efficiency. However, the use of irrigation water with a salinity of 5.2 dSm-1 caused a significant reduction in yield and water use efficiency at a 1% level. Moreover, the salinity of irrigation water increased the upper baseline in the Idso diagram and the upper side of the proposed trapezoid of Moran, but it had no effect on the baseline (plant transpiration limit under standard conditions). As a result, according to the definition of CWSI and WDI indices, these two indices decreased by 19% and 22%, respectively compared to the control treatment. The average optimal CWSI and WDI in the first (non-saline) treatment were 0.39 and 0.38, respectively, and they were 0.33 and 0.32 in the very saline treatment, respectively. This showed a decreasing trend of irrigation frequency with increasing salinity of irrigation water.

This study was carried out in the Agro-industry Complex of Gohar Kouh, Khash in Iranshahr. A split-plot experiment based on RCBD was employed with three irrigation intervals including 1: 30 day interval 2: 40 days of irrigation interval 3: 60 day irrigation interval along with three levels of nitrogen application including 1: no nitrogen fertilizer 2: 750 grams of nitrogen fertilizer per tree 3: 1500 grams of nitrogen fertilizer per tree as a sub plots. The results showed the highest yield was 4349 grams per tree that belonged to trees irrigated in 30 day intervals, and with the highest nitrogen application level. The lowest yield was obtained from I40N0, I40N750, I60N0 treatments. Each of the irrigation interval treatments with N0 level showed the lowest vegetative growth. Vegetative growth was improved by increase in nitrogen application level in most of the treatments. The most vegetative growth rate was obtained from the treatments of I30N1500 and I40N750 namely 13 and 12.4 centimeters of growth respectively while the lowest vegetative growth was obtained from treatments of I60N0 and I40N0 namely an average of 7.2 centimeters of vegetative growth. Results indicated that, the most nitrogen concentration resulted in leaf growth of 1.9 percent (I60N1500 treatment) while the lowest nitrogen concentration (I30N0 treatment) ended up with a leaf growth of 1.4 percent.