Selection criterion for improved grain yields in Ethiopian durum wheat genotypes

Abstract

Wheat (Triticum durum Desf.) is the most important cereal crop grown in the intermediate and highland areas of northeastern Ethiopia. Durum wheat dominates in these areas where water logging is the major production constraint. Because of the predominant problem of water logging coupled with other various biotic and abiotic production hobbling factors, the average productivity of wheat in the northeastern region never exceeds 8.4 ha -1, which is below the national average of 14.4 ha -1 (ECSA, 2002). Screening of wide durum wheat germplasm has been undertaken to improve durum wheat grain yield. But, selection based on the performance of grain yield alone, a polygenically controlled complex character, is usually not very efficient. An experiment was conducted
at Geregera testing site of Sirinka Agricultural Research Centre, during the 2003-cropping season with the objective of estimating the associations between yield and yield-related traits and to identify direct and indirect effects of characters for durum wheat grain yield improvement. The experimental material consisted of 44 indigenous durum wheat genotypes, which are randomly taken from the indigenous germplasm collections. Mean sum of squares for all the characters considered showed highly significant differences (P<0.01) indicating the presence of adequate variability. Grain yield had strong positive correlations (P<0.01) with plant height, number of kernels spike-1, grain yield plant-1, biological yield and thousand-kernel weight. On the contrary, grain yield had strong negative correlation (p< 0.01) with days to heading suggesting that the usefulness of selecting early
heading genotypes with long grain filling period in improving grain yield. The results of genotypic correlation indicate that maximum positive direct effect on grain yield was exerted by biological yield (1.08) followed by days to maturity (0.91) and harvest index (0.69). While, maximum negative direct effects were exerted by days to
heading (-0.72) and grain filling period (-0.52). Therefore, days to heading, biological yield and harvest index could be used as an indirect selection criterion for better grain yield. Thus, selecting early heading genotypes having high biological yield and harvest index could improve grain yield.