Effects of irrigation interval and nitrogen fertilizer on quality characteristics related to viscosity in Gilaneh rice cultivar

Viscosity is used as the most important indicator in evaluating the cooking quality of rice. In order to investigate the best irrigation method and nitrogen application and their interaction effects on viscosity or cooking quality in Guilaneh rice cultivar, this experiment was conducted as a factorial experiment in a CRBD with 3 replications. Irrigation managements was considered in 3 levels(full irrigation, 7 and 14 day interval irrigation) and nitrogen fertilizer as the second factor in 3 levels(50, 75 and 100 kg/ha). It will achieve better cooking quality with higher peak viscosity, lower trough viscosity and lower final viscosity. In the study of the interaction effects of nitrogen fertilizer application and irrigation, the highest peak viscosity was observed in the treatment with 14-day interval irrigation and 75 kg nitrogen fertilizer per hectare (2707 Centipoise). The lowest trough viscosity was obtained in the treatment of 75 kg fertilizer and irrigation under flooding (1767 Centipoise). The lowest final viscosity was obtained with 7-day interval irrigation and 75 kg nitrogen fertilizer per hectare (3648 Centipoise). In the study of viscosity, the higher breakdown and lower setback indicate better cooking quality. The highest breakdown (881Centipoise), the lowest setback (957 Centipoise) and the lowest pasting temperature (84.54°C) were related to the treatment of nitrogen fertilizer 75 kg/ha and 7-day interval irrigation. Therefore, according to environmental conditions and recommendations to reduce fertilizer and water consumption, if there is no effect on yield, treatment with 7-day interval irrigation and nitrogen fertilizer 75 kg/ha to achieve the best cooking quality for Gilaneh cultivar is recommended.