Triple Test Cross Analysis for Genetic Components of Salinity Tolerance in Spring Wheat

Soil salinity poses considerable and increasing problems for agriculture, and is receiving much attention from plant breeders. The identification of genes whose expression enables plants to adapt to and/or tolerate salt stress is essential for breeding programs, but little is known about the genetic mechanisms of traits in saline conditions. The data obtained from 75 families produced by crossing 25 F2 plants derived from a cross between two spring hexaploid wheats, namely Siete Cerros (salt tolerant) and Axona (salt sensitive), to their parents and their F1 progenies, was subjected to triple test cross analysis. The genetic components (epistasis, additive and dominance) and their interactions with the environment (control - salinity) were detected for heading date, days to maturity, final plant height, spike length, ear weight, straw weight, number of grains per ear, grain yield per plant, 1000 grain weight, whole plant weight and harvest index. Epistasis was presented only for days to maturity (‘j’ and ‘l’ types) and plant height (‘i’ type) at control and spike length (‘j’ and ‘l’ types) at salinity condition. Additive component (D) was more important than dominance (H) especially in salinity condition. Dominance ratio, (H/D)1/2, was less than unity in both environments and heritability (h2) decreased for all traits at salinity condition