Yield components and nitrogen partitioning of maize in response to nitrogen before and after anthesis

Abstract

Zea mays hybrid XL66 was grown with irrigation in sand in the field and subjected to different rates of nitrogen supply from floral initiation to anthesis and again from anthesis to maturity. Nitrogen supply during spikelet differentiation affected grain number markedly. Nitrogen supply during grain filling had a small but significant effect on the rate of grain filling and an effect on the rate of nitrogen entry to the grain, causing a 1.3-fold change in percentage grain nitrogen. Increasing the nitrogen supply produced larger plants, but the distribution of nitrogen and dry weight among plant parts were similar and the harvest indices for dry weight (0.46) and nitrogen (0.66) were the same over all nitrogen treatments. We found no evidence that shoot size per se controlled grain number or rate of grain growth; rather, fertilizer management during spikelet differentiation had most effect on yield of XL66.