The effects of some Agronomic Traits on Forage Yield of Sorghum under Different Levels of Nitrogen and Zinc sulfate Applications by Using Multivariate Statistical Analysis

In order to determine the some effective traits on dry forage yield of forage sorghum under different levels of nitrogen and zinc sulfate applications, a split plot experiment based on Randomized Complete Block Design with 3 replications was conducted at Agricultural Research Station in Dehloran Town where located in South Western of Ilam Province during summer of 2016-17. Three levels of nitrogen including: 0. 100 and 200 kg/ha of Urea fertilizer was arranged in main plots and zinc sulfate applications including: 0, 20, 40 and 60 kg/ha were allocated in sub plots. The effect of nitrogen and zinc sulfate was significant on all of studied traits except of leaf numbers. Results of multiple linear regression analysis indicated that the leaf dry weight, plant height, leaf numbers, tiller numbers, stem diameter, and digestible dry matter had the most influence on dry forage yield. Their influences accounted for 88% of sorghum dry forage variances. Results of stepwise regression indicated that the leaf dry weight (60%), tiller numbers per plant (22%) and stem diameter (20%) included the 85% of total forage yield variances. Finally, these results showed that to obtain the desirable forage yield of sorghum, the fertilizers must be manages typically that hold the leaves dry weight, tiller numbers and stem diameter in suitable levels.