Path coefficient analysis of N nutrition on yield and yield components for rice in a highly percolating soil

Data pertaining to grain yield, yield parameters, and N uptake during different periods of rice growth, in three field experiments, were subjected to the statistical procedure of path coefficient analysis. The observed grain yield response to the applied fertilizer N was predominantly reflected in an increased panicle density and spikelet number. The 1,000‐grain weight was only slightly influenced by N fertilization. Since both panicle density and spikelet number are known to be largely determined within 70 days after transplanting (DAT), N uptake during this ‐period was found to be critical to achieve a maximum grain yield response to applied N. The K uptake during 0–40 DAT correlated positively with panicle density, whereas absorption of N during 40–70 DAT determined both panicle density and spikelet number. Since N uptake during 0–20 DAT exerted a significant positive influence on grain yield through increased panicle density, the basal application of a part of fertilizer at the time of transplanting was justified.