Breeding for Salinity‐Stressed Environments: Recombinant Inbred Wheat Lines under Saline Irrigation

Abstract

Disposal of saline drainage water poses a difficulty in some cropping systems. This study investigated the reuse of such water for irrigating winter‐planted spring wheat (Triticum aestivum L.) in the San Joaquin Valley of California. Uniform salinization with a controlled degree of salinity presents a new target cropping system for plant breeding. Our objectives were to measure genetic and environmental variance components for agronomic traits and stress susceptibility index (S), using 43 recombinant inbred lines (RILs) and their parents, ‘Anza’ and ‘Cajeme 71’, grown under three saline irrigation treatments (control, 0.6; intermediate, 7.0; and high, 14.0 dS m‐1) and two N fertilization rates (160 and 260 kg N ha‐1) in 2 yr. Soil water conductivities at harvest time were 1.2, 4.4, and 9.4 dS m‐1 (2 yr means) after the three irrigation treatments. Grain yield reductions after the 7.0 and 14.0 dS m‐1 treatments were 5 and 19% in the first year and 36 and 68% in the second year. In both years genetic variances were significant and genotype ✕ environment interaction variances were not significant for grain and biomass yields and harvest index. Broad‐sense heritabilities estimated each year were low for grain yield (0.30 and 0.10) and biomass (0.07 and 0.02). Differences in S, based on grain yields in the low and intermediate salinity treatments, were nonsignificant in both years among RIL, but indicated a higher salinity tolerance of Anza than Cajeme 71. It was suggested that selection in low salinity environments would produce cultivars with high yield potential for environments with moderate salinity stress (soil conductivity of ≈7 dS m‐1), as may be prescribed with a controlled saline irrigation cropping system for wheat.