Importance of seed Zn content for wheat growth on Zn-deficient soil

Abstract

Two wheat (Triticum aestivum L.) genotypes (Zn-efficient Excalibur and Zn-inefficient Gatcher) were grown from low-Zn (around 250 ng Zn/seed) and high-Zn seed (around 700 ng Zn/seed) in a Zn-deficient siliceous sand fertilised with 0, 0.05, 0.2, 0.8 or 3.2 mg Zn kg-1 soil. At maturity, plants derived from the high-Zn seed had bigger grains and produced more grains than plants grown from the low-Zn seed when fertilised with nil Zn. Plants grown from high-Zn seed produced more grain dry matter per unit of Zn absorbed by the above-ground parts, transported a larger proportion of absorbed Zn to the grain, and approached the maximum harvest index with the fertilisation rate of 0.05 mg Zn kg-1 compared to 0.2 mg Zn kg-1 soil required for plants derived from the low-Zn seed. The Zn-efficient cv. Excalibuir had greater fertiliser efficiency when fertilised with 0.05 mg Zn kg-1 soil and a greater harvest index at nil Zn treatment compared to the Zn-inefficient cv. Gatcher. Zn-deficient plants produced seed with higher concentrations of all inorganic nutrients determined except Zn. There was a positive relationship between grain dry weight and Zn concentrations in youngest expanded blades sampled at 6 weeks of growth. It is concluded that crops grown from seed containing higher Zn content have a distinct advantage which culminates in greater yield when grown in soils of low Zn status.