Yield Relationships of Barleys Grown in a Tropical Highland Environment

Grain yield in barley (Hordeum vulgare L.) can be improved by understanding the interrelationships among yield, yield components, vegetative growth, and growth durations. The objective of this study was to determine for barley genotypes adapted to low‐input tropical highlands the extent to which grain yield was related to: (i) vegetative and mature heights, straw yield, and vegetative and grain‐filling durations and (ii) yield components determined by correlation and ontogenetic path analysis. Data were obtained from 26 barley genotypes tested in factorial combinations of N (0 and 11.5 g m−2) and P (0 and 2 g m−2) in 1998 and 1999 at Holetta, Ethiopia. Grain yield was correlated positively with straw yield, vegetative and mature heights, and grain‐filling duration. Grain yield was correlated positively with harvest index and correlated negatively with vegetative duration in the cooler season. Vegetative duration influenced grain yield negatively under low N and in the cooler season but positively under high N. Mature height influenced grain yield negatively under high N. Vegetative height influenced vegetative duration negatively. Spikes per square meter followed by kernels per spike largely determined grain yield. However, spikes per square meter had a strong negative effect on kernels per spike. Kernel weight had little effect on grain yield. Early shoot height association with yield and time to maturity may suggest an adaptive strategy for capturing the early flush of mineralized N and an escape mechanism from drought towards season end. Early shoot height can serve as an indirect selection criterion for high grain yield and early maturity for this gene pool grown in a tropical highland environment.