تیمور سهرابی
علیرضا کیانی
ابراهیم پذیرا
حسین فرداد

The climatic conditions of Iran requires that in order to optimize the use of water and to increase the irrigation efficiency, sprinkler irrigation systems shoud be used. On the other hand, water scarcity encourages the use of this type of irrigation systems which conserve water. unfortunately water scarcity is often accompanied by poor water qualty. Under conditions of low water quality, sprinkler irrigation has deterimental effects due to leaf burn and defoliation. In order to quantify yield reduction under this type of water, an experiment was set up on the agricultural research station. Varamin, Tehran in a completly randomized block design. irrigation systems (sprinkler and furrow) with water having four levels of salinity (0.63, 2.13, 3.97 and 7.8 ds/m) with four replications to evaluate the extent of leaf injury, foliar obsorption of C1 AND Na and yield response. The evaluation of the chemical analysis of leaves on the sprinkler plots indicated that the rate of ion absorbtion was increased during the growing season but on the furrow irrigated plots, the rate of absorbtion was not significant. Ion absorbtion other than C1 and Na were not significant for both the splinkler and furrow irrigated plots. The yield reduction of cotton on the treatment levels of 2.13, 3.97 and 7.8 ds/m on the sprinkler irrigated plots were about 9,25 and 36 percent, respectively, compared to treatment level of 0.63 ds/m but, statistically speaking, there were no significant differences between the treatment levels of 1 and 2. The yield reduction of cotton on the treatment level of 7.8 ds/m compared to treatment level of 0.63 ds/m on the furow irrigated plots was 19 percent.

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