Yield response of low and high-yielding rice varieties to nutrition management improvement

Fertilizer management is one of the most important managements to improve production and also to minimize its harmful effects on the environment. The aim of this study was to investigate the effect of optimal and conventional application of nitrogen (N), phosphorus (P) and potassium (K) on the yield of low-yielding (Deylamani and Hashemi) and high-yielding (Fajr and Shirodi) rice varieties. The experiment was conducted as a split plot in a randomized complete block design three replications at a research farms of Sari University of Agricultural Sciences and Natural Resources in 2019. In the absence of any of N, K and P fertilizers, yield of Shiroodi cultivar was 5458, 8399 and 9926 kg ha-1, respectively, and yield of Fajr cultivar was 4894, 7364 and 8903 kg ha-1, respectively. In low-yield cultivars, in the absence of any of N, K and P fertilizers, yield in Hashemi cultivar was 2969, 5134 and 4925 kg ha-1, respectively, and yield in Deylamani cultivar was 3028, 5408 and 5384 kg ha-1, respectively. Optimal application of N, P and K fertilizers caused a significant increase of 82, 65, 55 and 34% of yield in Shiroodi, Fajr, Hashemi Tarom and local Tarom cultivars, respectively, compared with the current application of these three nutrients. The results showed that a suboptimal application of nitrogen, phosphorus and potassium fertilizers is a main limiting factor for rice production, and improving the amount and split application of these fertilizers simultaneously can increase yield by 59% compared to their current application in the region.