Effect of Nitrogen Fertilizer and Plant Density on Growth Characteristics, Yield Components and Grain Yield of Rice

In order to investigate the effect of nitrogen fertilizer and plant density on the agronomic characteristics of rice cv. Tarom Hashemi, a field experiment was carried out as a randomized complete blocks design with three replications during 2018 and 2019 in a farm located in Sari, north of Iran. The present study consisted of 10 levels of plant density (hills m-2) and N fertilizer, named T1 (20 hills + [50 percent after transplanting + 50 percent at the beginning of tillering]), T2 (20 hills + [33.3 percent after transplanting + 33.3 percent at the beginning of tillering + 33.3 percent at panicle formation]), T3 (20 hills + [40 percent after transplanting + 40 percent at the beginning of tillering + 20 percent at the end of panicle emergence]), T4 (20 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.33 percent at the end of panicle emergence]) as a control, T5 (30 hills + [33.3 percent after transplanting + 33.3 percent at the beginning of tillering + 33.3 percent at panicle formation]), T6 (30 hills + [40 percent after transplanting + 40 percent at the beginning of tillering + 20 percent at the end of panicle emergence]), T7 (30 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence]), T8 (30 hills + [25 percent after transplanting + 25 percent at the beginning of tillering + 25 percent at panicle formation + 25 percent at the end of panicle emergence]), T9 (40 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence]), and T10 (40 hills + [40 percent after transplanting + 40 percent at panicle formation + 20 percent at the end of panicle emergence])..The results showed that the effect of year was not significant on grain yield. But the grain nitrogen concentration was lower in the second year (with a difference of 0.185 percent). The maximum total number of tillers per hill (18.61 tillers), panicle length (25.0 cm) and harvest index (40.9 percent) were obtained under T1, T2 and T3 treatments, respectively. Grain yield was not affected by the experimental treatment, however, its maximum (6865 kg ha-1) was obtained under T9 treatment due to an increase in the number of panicles per square meter (510 panicles), indicating an increase of 19.0 percent compared to the control treatment (T4). A density of 40 hills per square meter with nitrogen splitting of 33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence (T9) is recommended to achieve maximum grain yield of rice under the conditions of this experiment in northern Iran.