Is increased radiation use efficiency in sorghum related to increased height

Abstract

Sorghum yield is known to correlate with height in breeding populations and some recent studies have found enhanced radiation use efficiency (RUE) in a tall (single dwarf) sorghum hybrid, which may explain the correlation. The experiments reported in this paper were undertaken to investigate whether plant height per se was related to radiation use efficiency in sorghum. Two field experiments were conducted with mutant lines differing only in one height gene – conventional triple dwarfs and their mutated (taller) double dwarfs. In experiment 1, a significant increase in biomass due to higher RUE was observed for the tall mutant in one genetic background but not in the other. In experiment 2, however, the same genotype showed significantly increased biomass with the tall mutant form, but this was caused by enhanced light interception rather than difference in RUE. Hence, at this stage it was not possible to draw a clear conclusion about the possible relationship between RUE and height in sorghum. The question remains unresolved and is the subject of on-going study.