Nitrogen uptake and nitrogen harvest index in durum wheat cultivars varying in their grain protein concentration

Summary In a field experiment, plant (excluding roots) and grain nitrogen at harvest were estimated in 15 durum wheat cultivars varying in their grain protein concentration. They showed significant variation in grain yield, grain protein concentration, biological yield, total plant nitrogen at harvest and residual nitrogen in straw. Harvest index and nitrogen harvest index were calculated from this primary data. Nitrogen harvest index varied from 57 to 83%. Plant nitrogen showed significant positive correlation with biological yield, grain yield and grain protein yield, but the correlations with grain protein concentration, harvest index and nitrogen harvest index were not significant. Nitrogen harvest index was positively correlated with harvest index indicating that the distribution of N between straw and grain to a large extent, but not entirely, depends upon the partitioning of dry matter between the two. Grain protein concentration was neither correlated significantly to plant nitrogen nor to nitrogen harvest index.