Effect of Soil Fertility and Plant Competition on Grain Sorghum Panicle Morphology and Panicle Weight Components1

Abstract Panicle weight components (i.e., number of branch whorls per panicle, number of branches per whorl, number of grains per branch and grain weight) and rachis morphology were analyzed under different soil fertility and plant population treatments. High soil fertility and low plant competition increased the 1000‐grain weight and number of grains per panicle. The latter component was affected by soil fertility through the number of branches per whorl and the number of grains per branch, and by plant competition through the number of whorls per panicle and the number of grains per branch. Higher soil fertility and lower plant competition promoted a longer panicle through the increase in rachis internode length and number of internodes, respectively. The degree of contribution of some components to the number of grains per panicle was not always equal throughout the length of the panicle. A negative correlation, which became stronger as the number of grains per panicle increased, was found between weight of grain and number of grains per branch. Intra‐panicle competition between these components was suggested.