Relationship of yield components of main culms and tillers of grain sorghum

Abstract

Abstract An experiment was conducted in 1974 and 1976 at Columbia, MO (U.S.A.) to assess the relationship of grain yield components of main culms and lateral tillers of grain sorghum (Sorghum bicolor (L.) Moench.). Tillering was regulated by removing differing numbers of tillers at three stages of development (8-leaf, flag leaf visible, and 50% anthesis). Four levels of tillering were allowed at each stage: 0, 1, 2, and a variable number (control) of tillers per plant. Number of kernels produced by and weight of grains from main culm panicles decreased as number of tillers allowed to develop increased (15 and 9%, respectively). When increased intraplant competition interacted with moisture deficiency in late-planted plots, the deleterious effect on these components was exacerbated (19 and 12%, respectively). Yet, with increased competition, declines in number of kernels produced by main culm and kernal weight of grain from main and lateral tillers was more than compensated for by the total number of kernels produced. Time of tiller removal was important to main culm yield component expression if all tillers were removed. For number of kernels it was necessary to remove all tillers at the 8-leaf stage of development if a significant increase over the other removal treatments was to occur. On the other hand, kernel weight was not affected significantly unless removal was delayed until 50% anthesis. Allowing only one tiller to develop provided sufficient intraplant competition to negate any advantage in time of tiller removal within wach treatment. Yield components of lateral tillers were unaffected by removal of excess tillers at various stages development.