effects of nitrogen and drought stress on yield components, yield and seed quality of corn (s.c. 704)

in order to study the effects of nitrogen and drought stress on yield, yield components and seed quality of corn (hybrid single cross 704) a field experiment was conducted at agricultural research station in islamabad gharb in 2009. experiment design was split plots based on randomized complete block design with three replications. main plots included full irrigation requirement, 80 percent and 60 percent of full irrigation requirement and nitrogen (as urea) included: recommended amount based on soil test (170 kg of pure nitrogen per hectare), 30 percent more than this amount (221 kg of pure nitrogen per hectare) and 30 percent less than this amount (119 kg of pure nitrogen per hectare) inserted as sub-plots. the results showed that depending on stress severity drought caused reducing of leaf area index, plant height, biological yield, grain's starch content, yield and yield components. so that severe drought stress decreased the grain yield to 45.62 percent as compared to full irrigation. application of nitrogen fertilizer equal to 170 kg/ha increased leaf area index, plant height, biological yield and  yield components, that finally caused increasing the grain yield, but nitrogen application more than plant demand (in drought conditions) didn't have a positive effect on the yield. in the present study increasing the soil moisture and nitrogen simultaneously increased the grain yield, but using more nitrogen fertilizer under the condition of water stress decreased the grain yield. the maximum amount of grain yield (19.23 t/ha) was achieved from full irrigation and 221 kg/ha nitrogen and the lowest amount (9.17 t/ha) was obtained by treatment of severe drought stress and same amount of fertilizer