Effect of NPK Fertilization Rates and Splitting on the Grain Yield and its Components of Two Sorghum Cultivars

A field experiment was conducted at the Agronomy Department Farm, Faculty of Agriculture, Assiut University during the 2012 and 2013 summer growing seasons to study the effect of NPK fertilization rates and splitting on the grain yield and its components of two sorghum cultivars. The experiment was carried out in a randomized complete block design (RCBD) using split-split plot arrangement with three replicates. Cultivars were occupied at main plot while NPK rates were allotted on sub plot and splitting doses of NPK were allocated on sub sub plot. The obtained results showed that:
Plant height, Panicle weight, Seed index and Grain yield /fed were affected significantly by studied cultivars in both seasons. Giza 15 cultivar surpassed the Dorado one and gained the highest mean values of mentioned traits in both seasons. The application of NPK fertilizers exerted a significant influence on plant height, panicle weight, seed index and grain yield /fed in the two growing seasons. The highest mean values of panicle weight, seed index and grain yield fed^-1 were obtained when sorghum plants fertilized by 125% NPK/fed of the recommended fertilizers in both seasons. Splitting NPK into four equal doses resulted in the highest mean value of plant height in both seasons while, panicle weight, seed index and grain yield /fed traits were responded to three equal doses in the two growing seasons. Also, the all first order interactions (varieties × NPK rates, varieties × splitting number and NPK rates × splitting) exerted a significant influence on plant height, panicle weight, seed index and Grain yield /fed in both seasons. The second order interaction (varieties × NPK rates × splitting) exerted a significant influence on plant height; panicle weight, seed index and grain yield /fed in the two growing seasons. The highest value of grain yield/ fed was obtained from Giza 15 cultivar when received the highest NPK rate (125% NPK/fed of the recommended fertilizers) applied at three equal doses in both seasons.