Effect of different super absorbent polymer and animal manure ratios on the quantitative and qualitative characteristics of soybean under drought stress

To investigate effects of different super absorbent polymer and animal manure ratios on the quantitative and qualitative characteristics of soybean under drought stress, a split plots experiment was conducted based on randomized complete block design with three replications in Marvdasht, Iran in 2009. Main factor included of irrigation with 50, 100 and 150 mm evaporation from pan class A and sub factor included of control, 40 t.ha-1 animal manure, 200 kg.ha-1 super absorbent polymer, 50 percent super absorbent polymer + 50 percent animal manure, 65 percent super absorbent polymer + 35 percent animal manure and 35 percent super absorbent polymer + 65 percent animal manure. The results showed that, number of pod and grain per plant, 1000 grain weight, grain yield, biological yield, protein yield and oil yield were decreased by drought stress occurrence and were increased with super absorbent polymer and animal manure application. The highest yield (2148.3 kg.ha-1) was obtained in control treatment. Results showed that the combinations of super absorbent polymer and animal manure significantly increased grain, biological, oil and protein yield compared with control. Finally, combination of 35 percent super absorbent polymer and 65 percent animal manure was the best treatment in this experiment.