Effect of irrigation interval and N fertilizer application on morphological traits, yield and yield components of millet (Panicum miliaceum L.)

Introduction Iran with mean annual precipitation of 240 mm is categorized in arid and semi-arid zones of the world. High evapotranspiration and limitation of water resources are important environmental parameters that caused reduction of the plants yield in Iran. Also nitrogen deficiency affects the partitioning of assimilates among vegetative and reproductive organs and can influence the growth and yield of the plants. Therefore, given the importance and different roles of water and nitrogen in vital processes of the plants, the objective of the present research was to study the effect of irrigation interval and N fertilizer application on morphological traits, yield and yield components of millet in Birjand, Iran. Materials and Methods This research was conducted as split-plots based on a Randomized Complete Block Design with three replications, at Agricultural Research Center of Birjand branch, Islamic Azad University in 2009. The main plots included irrigation interval at three levels (7, 14 and 21 days) and the sub-plots were N fertilizer application at five levels (control or 0 kg N. ha-1, 50 kg N. ha-1, 50 kg N. ha-1 + foliar application, 100 kg N. ha-1 and 100 kg N. ha-1 + foliar application kg N. ha-1). The texture of the soil in research farm was loam with the pH of 8, electrical conductivity of 4.49 mmhos cm-1 whose organic carbon, total N, P, and K content was 0.32%, 0.08%, 16.4 ppm and 501 ppm at the depth of 0-30 cm, respectively. In the end, all data were analyzed by MSTAT-C statistical software and means were compared by Duncan Multiple Range Test at 5% level. Results and Discussion The results of analysis of variance indicated that the effect of irrigation interval on plant height, panicle number per m2, 1000-seed weight, seed yield and biological yield were significant. Also, plant height, flag leaf area, panicle number per m2 and seed yield were significantly affected by nitrogen levels. Interaction of irrigation interval and N fertilizer only significantly affected1000-seed weight. Means comparison indicated that the increase in irrigation interval from 7 to 21 days decreased plant height, flag leaf area, panicle number per m2, 1000-seed weight, seed yield and biological yield, 36.8, 33.6, 32.9, 18.5, 44.4 and 40.1 percent respectively. Also, 50 kg N. ha-1 + foliar application treatment increased plant height, flag leaf area, panicle number per m2 and seed yield, 20.4, 21.9, 47.8 and 52.3 percent, respectively as comparison with non-nitrogen application treatment. It is seems that water deficit stress, due to its effect on photosynthesis, respiration, ionic absorption, nutrients and hormones metabolism processes reduced the growth of stem and leaf cells and decreased leaf area and led to a decrease in flowering and grain filling period which finally caused reduction of yield and yield components. Probably, the decrease in leaf area is a response to stress for adapting water deficit conditions and survival through decreasing transpiring area of the plant. Moreover, with the increase in N application, plant photosynthesizing area and assimilate production increased and therefore seed yield increased. Conclusions In total, the results of the current study indicated that water and nitrogen deficiency significantly decreased millet economical yield mainly by decreasing panicle number per m2. Finally, results of research showed that treatment of 7 days irrigation interval and 50 kg N. ha-1 + foliar application recommended for the cultivation of millet in Birjand region for production maximum of millet seed.