The harvest index of individual ears of four South African wheat (Triticum aestivum L.) cultivars

Abstract

Increasing the harvest index is a major route to higher yields in regions where a crop has had a lengthy period of selection and adaptation. No information could be found on differences in the harvest indices of the main stems and tillers of South African wheat cultivars. Consequently, this was determined for four wheat cultivars grown in South Africa in a long-term fertilization and irrigation experiment at the University of Pretoria. The four cultivars did not differ in main stem (MS) harvest indices with a mean of 0.44. The harvest index of first tillers (T,) differed significantly with SST 86 having the highest (0.48) and Carina the lowest (0.29), with that of Kariega and Inia intermediate between SST 86 and Carina. The low harvest indices of second tillers (T₂) indicate less effective utilization of resources by the tillers. The data indicate that individual wheat ears differ in the partitioning of assimilates to the grain and this may help in identifying cultivars efficient in assimilate utilization for improved grain yield.