Analysis of genotype x environment interaction and assessment of stability parameters for earliness and yield of some pea. (Pisum sativum L.) genotypes under south valley environmental conditions.

摘要

Field studies were conducted in Egypt, during the 2006/07, 2007/08 and 2008/09 winter cropping seasons, to compare 10 local and introduced pea accessions for abiotic stresses (heat and drought) tolerance, using stability analysis. The treatments comprised 10 pea genotypes (G) sown at 3 different dates (early, 10 October=D₁, intermediate, 10 November D₂ and late, 10 December D₃) in every season (Y). Peas received 2 water irrigation water stress treatments (I). So, 18 manipulated environments (3 years x 3 planting dates x 2 water stresses=18 E's) were formed to analyse G x E interactions and, also, to estimate stability indices of earliness and yield for the 10 pea genotypes. Pea genotypes showed different responses to environments. Early planting (10 October) hastend flowering and maturity date. Intermediate planting (10 November) gave the tallest plant and caused increase in number and weight of fresh pods/plant and total green pod yield/Fed, compared too early and late planting dates. Irrigation every 12 days (water stress) reduced the number of days to flowering and maturity, number of seeds/pod, pod length (cm), number and weight of pods/plant and total green pod yield by averages of 6.73, 6.44, 20.52, 5.16, 0.97, 29.83, 15 and 47.23% compared to irrigation every 6 days (control), respectively, in the 3 seasons. The joint regression analysis of variance revealed highly significant differences among genotypes, environments and G x E interactions for all studied traits. Partitioning the G x E interaction mean squares indicated that the G x E (linear) mean square was highly significant for all the studied traits, except for days to flowering and maturity date, suggesting that most of interaction were a linear functions of the environmental values as indicated by the greater magnitudes of G x E (linear) in comparison with the E+(y+E) mean squares. The E+(V+E) mean squares were also highly significant for all the studied traits, indicating that the non-linear components of G x E interaction were data operating. The regression coefficients were correlated positively with mean performance over 18 environments, indicating that the low yielding genotypes were generally stable, while the high yielding ones were rather responsive. The stable genotypes 1 for yielding; 2, 4 and 7 for days to flowering; 2, 3 and 5 for maturity; 2, 3, 6, 7 and 8 for pod length; 1, 3, 5 and 6 for maturity; 2, 3, 6, 7 and 8 for pod length; 1, 3, 5 and 6 for number of seeds/pod; and 4 and 8 for number of pods/plant were considered specially adapted to stress environments. Superior stable genotypes with high mean performances compared to the general means over all environments were identified. These included 2 and 4 for days to flowering; 2 for maturity; 3, 6 and 8 for pod length; and 1, 5, 6 and 8 for number of seeds/pod. Such finding could be useful for improving pea adaption to heat and drought through selection.