exploring the possibility of reducing deficit water stress damage on yield of forage sorghum by foliar application of salicylic acid and zinc sulphate

according to the global water shortage problem, the exploring for reducing its harmful effects is very important. this experiment was conducted as split plots method based on randomized complete block design with three replicates in urmia university research field during growing season of 2013-14. water deficit stress as main plot consisted of three levels (irrigation when soil moisture reached 90, 70 and 50 percent of soil field capacity) and foliar applications (at 5-6 leaf stage two times with an interval of three days) as sub plot with five levels including: no foliar application (control), foliar application of salicylic acid (0.5 and 1 millimolar) and zinc sulphate (300 and 3000 milligram per liter). the results showed that the interaction effect of foliar application and water deficit significantly influenced photosynthetic pigments (except total chlorophyll content) and relative water content. the main effects of foliar application and water deficit were significant on leaves number, dry weight of leaves and stems, forage yield per square meter, electrolyte leakage and leaf area index. severe water deficit significantly decreased dry matter yield by 21.11 percent relative to normal irrigation. the maximum forage dry matter yield with average of 1571.53 gram per square meter were produced by both foliar application of zinc sulphate 3000 milligram per liter and salicylic acid 0.5 millimolar, which not only compensate for spraying costs but also lead to an acceptable increase in farmers' income. therefore they could be recommended for farmers.