Pearl millet (Pennesitum americanum) forage yield under different irrigation regimes and nitrogen fertilizer rates

Growing drought tolerant crops such as pearl millet can save water where irrigation water supply is limited. The objective of this project was to evaluate the pearl millet (Pennesitum americanum) forage yield under different irrigation regimes and nitrogen fertilizer rates. The field experiment was designed as a split factorial arrangement in randomized complete block design with four replications at the Research Field of University of Tehran, Karaj, in 2007. The combination of Irrigation regimes (40, 60, 80 and 100 % maximum allowable depletion of available soil water) and nitrogen fertilizer rates (0, 75, 150 and 225 kg N ha-1) were allocated to the main plots and harvest was assigned to the sub plots. It was observed that 40 and 60% maximum allowable depletion of available soil water produced the highest dry matter yield over three harvests (21.45 and 20 t ha-1, respectively). As water depletion increased to 100% maximum allowable depletion of available soil water and getting close to the third harvest, the leaf and total dry matter yield followed a decreasing trend. At 40% maximum allowable depletion of available soil water treatment, the highest total dry matter was produced on first harvest. The interaction effect of harvest×nitrogen was highly significant on total dry matter yield. The highest yield was produced on second harvest at 225 and 150 kg N ha-1. The lowest dry matter was produced in control treatment over all harvests. Therefore, by 60% depletion of maximum allowable depletion of available soil water and consuming 150 kg N ha-1, acceptable dry matter yield could be produced.