Quantifying nutrient harvest indices and uptake patterns for six hard spring wheat genotypes grown under contrasting nitrogen supply

Abstract

Wheat nutritional quality can be characterised by nutrient concentrations in the grain. This is the sum of nutrient uptake by the roots and re-translocation from other organs during grain filling. It is quantified by the Nutrient Harvest Index (NuHI: the fraction of total accumulated nutrient that is allocated to the grain). In contrast to nitrogen (NHI), there has been little quantification of NuHIs among modern hard spring wheat genotypes, when grown under contrasting N supply. We investigated NuHIs for six macro- and four micro-nutrients among six hard spring wheat genotypes, both under field and glasshouse conditions. There was consistency in element-specific NuHI values between experiments and amongst genotypes. Values ranged from 0.09 to 0.86, with highest NuHI found for phosphorus (P; 0.86) and N (0.82) and lowest values (<0.25) for calcium, copper, iron and potassium. NuHIs were higher under low N supply for all elements, except P, manganese and zinc, which were unaffected by N supply. This reflects the greater deposition of carbohydrate in higher yielding (N fertilised) crops. Thus, NuHIs for the hard spring wheat genotypes tested were highly element specific, and decreased with N supply within a given environment. HIGHLIGHTS Nutrient Harvest Index (NuHI) was similar between field and controlled environment NuHIs were consistent across six modern spring wheat genotypes NuHIs were in large element-specific ranging from 0.09 for potassium to 0.86 for phosphorus Limited N supply increased NuHIs mainly through reduced grain yield