Selection Criteria for Combining High Grain Yield and High Grain Protein Concentration in Bread Wheat

Abstract

This study was designed to identify selection criteria for the simultaneous improvement of grain yield and grain protein concentration in spring wheat (Triticum aestivum L.). Eight cultivars were selected. Six expressed contrasting levels of grain protein concentration and grain yield. Two, the cultivars ‘UM632’ and ‘UM684’, expressed high levels of both traits concurrently. Plants in replicated plots were sampled from anthesis to maturity over 2 yr and data were collected on traits related to nitrogen (N) and dry matter accumulation and remobilization. Grain protein concentration was not correlated with grain yield but was correlated with post‐anthesis N uptake (r = 0.66**), total plant N at maturity (r = 0.49**), and N harvest index (r = 0.87**), and was inversely correlated with vegetative N at maturity (r = −0.49**). Grain yield was correlated with both post‐anthesis N (r = 0.50**) and dry matter uptake (r = 0.58**), with total N (r = 0.78**) and dry matter (r = 0.77**) at maturity, and with harvest index (r = 0.83**). Grain protein yield was highly correlated with post‐anthesis N accumulation (r = 0.90**), total N at maturity (r = 0.98**) and the sum of N harvest index and harvest index (r = 0.93**). UM632 and UM684 coupled high post‐anthesis N uptake and total N at maturity with high remobilization efficiency and N harvest index, while maintaining harvest index. We concluded that grain protein concentration and grain yield could be improved simultaneously if selection was practiced for threshold levels of grain yield or protein concentration followed by selection for grain protein yield in populations constructed from crosses combining high total N at maturity, N harvest index and harvest index.