Effect of time and intensity of defoliation on quantitative and qualitative characteristics of soybean (Glycine max L.) under the consumption of amino acids condition

In order to investigate the effect time and intensity of defoliation under use of amino acid condition, a factorial experiment was conducted based on randomized complete block design with three replications in Ali Abad Katoul, Golestan Province during growing season 2016-17. The first factor included the intensity of defoliation at three levels of 0, 50 and 100%, the second factor included the time of defoliation in five levels (V1, V3, V5, V7, and R1), and the third factor was the application and non-application of amino acids. The results showed that the effect of amino acids, the time and intensity of defoliation, and the interaction between times in intensity of defoliation were significant on oil yield. Application of amino acid resulted in an increase of 98.9% of oil yield compared to the non-application treatment. The highest oil yield was observed in the defoliation of 50% leaf in V1 stage with a mean of 867.5 kg/ha, which was 10.5% higher than to the control treatment. Comparing the mean interactions effects of times in intensity of defoliation, the highest grain protein yield was observed in defoliation of 50% leaf in V5 stage with 1296.17 kg/ha, which increased 17.33% compared to the control treatment. Defoliation of 100% of leaves resulted in the lowest weight of 100 seeds, and the absence of leaf defoliation and the defoliation of 50% of the leaf had the highest mean of this trait. Application of amino acids increased 12.28% of grain yield compared to the non-application. In the interaction of the times in intensity of defoliation, the highest grain yield associated with 50% defoliation of leaf in stages V1 and V5 were 3681.9 and 3696.3 kg/ha respectively, which was 2.46 and 2.84% higher than to the control treatment, respectively. In general, leaf defoliation in late stages of growth (especially reproductive growth) with 100% intensity was reduced the quantitative traits (yield and yield components) and qualitative traits (oil and protein content of grain). On the other hand, the application of amino acids, by increasing the mean of measured traits, moderated the effect of defoliation stress.Defoliation of 100% of leaves resulted in the lowest weight of 100 seeds, and the absence of leaf defoliation and the defoliation of 50% of the leaf had the highest mean of this trait. Application of amino acids increased 12.28% of grain yield compared to the non-application. In the interaction of the times in intensity of defoliation, the highest grain yield associated with 50% defoliation of leaf in stages V1 and V5 were 3681.9 and 3696.3 kg/ha respectively, which was 2.46 and 2.84% higher than to the control treatment, respectively. On the other hand, the application of amino acids, by increasing the mean of measured traits, moderated the effect of defoliation stress.Defoliation of 100% of leaves resulted in the lowest weight of 100 seeds, and the absence of leaf defoliation and the defoliation of 50% of the leaf had the highest mean of this trait. Application of amino acids increased 12.28% of grain yield compared to the non-application.