Phenotypic characters associated with yield adaptation of wheat to a range of temperature conditions

Abstract

The range of adaptation of wheat ( Triticum aestivum L. emmend. Thell.) is influenced by temperature variation. This study was aimed at determining phenotypic characters that are associated with yield adaptation of wheat to a range of temperature conditions experienced in Zimbabwe. Thirty genetically diverse lines of wheat were grown in a field experiment from 1984 to 1986 at seven locations that ranged in altitude from 421 to 1506 m, providing different temperature conditions. Analysis of variance, correlation matrices and regression analysis of grain yield using the mean maximum temperature during pre-anthesis at the locations in each year as the environmental index, were done. The lines were divided into four classes of adaptation to temperature environments based on linear regression slopes and intercept, mean yield and estimated yield at the warmest environment. The regression slopes were negatively related ( P < 0.001) with grain filling duration and positively ( P < 0.01) with duration to anthesis. Differences in grain filling rate and grain weight per ear significantly ( P < 0.01) explained line variation of yield across all temperature conditions. Lines classified as well adapted to all temperature conditions had the highest mean yield, grain filling rate and grain weight per ear. The improvement of grain filling rate and grain weight per ear would appear to lead to increased grain yield of lines in all classes of adaptation, and wide adaptation to a range of temperature conditions. However, knowledge about the genetic basis of grain filling rate and/or grain weight per ear variation among lines is necessary for an effective and efficient use of these characters in breeding and selection for high yield across all temperature conditions.