Optimization of nitrogen fertilizer management for improving rice grain yield and nutrient accumulation and mobilization in saline‐alkaline soils

Abstract

Soil salinity and alkalinity are key abiotic stresses that limit crop growth and yield worldwide. Balanced N fertilization is important for improving rice (Oryza sativa L.) yield via efficient utilization of P and K under saline and alkaline soil conditions. In this study, a japonica rice cultivar, Kenjing 8, was used to investigate the effects of N fertilizer on rice yield, as well as N, P, and K status, in a 2‐yr field experiment in saline‐alkaline soil in Heilongjiang Province, northeast China. The plants were assigned to the following five treatment groups: no N fertilizer, or conventional, balanced, reduced, and postponed N fertilizer management. Compared with conventional N management practice, balanced and reduced N management practices increased the concentrations of N, P, and K in the leaves, stem‐sheaths, and panicles at full heading (FH) and maturity; however, postponed N management led to the opposite results. Balanced N management increased N, P, and K mobilization to the leaves (from FH to maturity) by 49, 43, and 67%, respectively, resulting in the highest crop yields among all the N management practices studied. Furthermore, rice yield was positively correlated with N, P, and K accumulation and rates of nutrient mobilization to the leaves, stem‐sheaths, and panicles at maturity. The application of 150 or 135 kg N ha−1, and the proportion of 4:3:1:2 in the pre‐transplanting, mid‐tillering, panicle initiation, and panicle differentiation stages, may increase rice yield and facilitate efficient utilization of nutrients in saline‐alkaline soil.

Change in phosphorus requirement with increasing grain yield for rice under saline-sodic stress in Northeast China

“…Among yield components, panicle and spikelet number was the basis of stable high yield of rice (Sheehy et al, 2001;Yan et al, 2010;Guo et al, 2020;Li et al, 2021). Our results showed that the number of panicles per hectare and spikelets per panicle were significantly increased with increasing grain yield levels (Table 2).…”

“…Frontiers in Environmental Science frontiersin.org documented in several previous studies (Rose et al, 2010;Bi et al, 2013;Wang et al, 2017;Wei et al, 2017;Guo et al, 2020). 60-90% of P taken up by the rice is typically accumulated in the grains at maturity (Rose et al, 2010;Bi et al, 2013).…”

“…Wang et al (2017) reported low straw P concentrations improved grain yield by enhancing P translocation into grain. In addition, the yield of rice in salinealkaline soils was positively correlated with P accumulation and rates of nutrient mobilization to the leaves, stem-sheaths, and panicles at maturity (Guo et al, 2020).…”

“…The high pH conditions of salinesodic soils generally result in the reduction of phosphorus absorption (Tian et al, 2016). The availability of P to the plant is limited by insoluble state of tricalcium phosphate in saline-sodic soils (Saito et al, 2019;Guo et al, 2020), so the P use efficiency (PUE) in saline-sodic soils are very low. P has become the main limiting factor affecting the growth and yield of rice under saline-sodic stress (Guo et al, 2020).…”

“…Grain yield of rice are associated with P concentrations in grains. Previous studies have reported differences in the rice grain yield -P uptake relationships over regions (environments), genotypes, irrigation, and nutrient (nitrogen and phosphorus) management strategies (Dobermann et al, 1996;Vandamme et al, 2016;Wang et al, 2017;Wei et al, 2017;Song et al, 2019;Guo et al, 2020). For example, Dobermann et al (1996) reported that uptake of 1.8-4.2 kg P was required to produce one ton of grain yield by using the data from long-term experiments at 11 sites in five countries of Asia.…”