Genetic gain in yield and protein over two cycles of a wheat recurrent selection program.

Increasing grain yield and protein are important wheat breeding goals. However, the simultaneous improvement of both traits is complicated by a strong negative correlation and genotype by environment interaction (G×E). A recurrent selection program (RSP) reported here was initiated to produce germplasm, which combined both high yield-potential and increased protein content for the northern wheat-growing region of Australia. Diallel crossing amongst 10 cultivars (6 high yield and 4 high quality cultivars), followed by random mating amongst the F1s were used to produce the founding segregating population. Two years of multi-environment trials were conducted in the GRDC Northern Grain Region (NR) for each of the foundation (RSA0) and first (RSA1) cycles of recurrent selection. Data from the two cycles were analysed to evaluate the genetic gain achieved over the two cycles of selection, based on five potential selection strategies. Selection based on yield or protein or yield-adjusted protein only increased selected trait but reduced the other traits. However, application of selection based on yield and protein or yield and yield-adjusted protein simultaneously increased both yield (4.7%, 6.0% for RSA0 and 4.0%, 4.2% for RSA1 respectively) and protein (2.1%, 1.3% for RSA0 and 1.7%, 1.6% for RSA1 respectively).