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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.

Integrated crop management practices can improve rice (Oryza sativa L.) grain yield, but the effects of such practices on dry matter accumulation and photosynthetic productivity are inconsistent and not well understood. The primary objective of this study was to investigate the effects of integrated crop management practices on dry matter accumulation and redistribution, photosynthetic production, and yield of rice in northeast China. Medium‐ and high‐yielding potential japonica rice cultivars were grown using four crop management practices, including no N application (N0), local farmers’ cultivation practice (FP), high‐yield cultivation practice (HYP), and super‐high‐yield cultivation practice (SHYP). The increases in average yield with the HYP and SHYP treatments were 16.87 and 36.70%, respectively, in 2017 and 14.70 and 31.05%, respectively, in 2018, compared with FP. Increases in effective panicle number and spikelet number per panicle were the main reason for the increase in yield under the integrated crop management treatments. Compared with FP, the HYP and SHYP treatments significantly increased the population dry matter by 26.40 and 56.64%, respectively, before the heading stage. Relative to N0 and FP, HYP and SHYP significantly increased the dry matter export, export rate, and translocation rate in the leaves, stems, and sheaths and significantly increased the photosynthetic potential throughout the growth stage and the net assimilation rate after the tillering stage. These increases were critical for improving the quality of rice and achieving higher yields. Our study provides a theoretical basis for the development of high‐yield cultivation methods for rice in northeast China.

Applying appropriate agronomic practices instead of conventional farming practices might improve rice yield. However, few studies have focused on how integrated agronomic practices affect N, P, and K accumulation and allocation in rice (Oryza sativa L.). Therefore, this study was conducted to investigate grain yield, N, P, and K accumulation, and allocation under different agronomic practices. A japonica rice cultivar was grown in the field, with four agronomic practice treatments: no N application (N0), local farmers' practice (FP), high-yield practice (HYP), and super-high-yield (SHY) practice. The results showed that the latter two practices significantly increased grain yield by 11.0% and 26.4%, respectively, compared with that under FP, mainly as a result of an increase in mean number of panicles m −2 and spikelets panicle −1 . Mean aboveground N, P, and K accumulation significantly increased by 24.9, 15.3, and 79.1%, in HYP and 42.0, 38.8, and 219.7% in SHY, respectively, compared with that under FP. In particular, K accumulation was higher than N and P accumulation in HYP and SHY plants than those in FP plants. However, N, P, and K grain productivity was lower by 7. 5, 9.5, and 20.3% under HYP, and 20.3, 17.2 and 62.7% under SHY treatments than that of FP, respectively, and N, P, and K grain productivity were negatively correlated with yield. Our results suggest that an increase in N, P, and K accumulation from the full-heading stage (FH) to the maturity stage (MS) may assist with improving rice yields under HYP and SHY treatments. 1238wileyonlinelibrary.com/journal/agj2

The integrated strategies for nitrogen management and planting density are important for improving rice (Oryza sativa L.) yield in saline-alkali soil; however, the optimal growth conditions for the Songnen Plain, China, are unclear. Here, we studied the effects of nitrogen application rate (NAR) (N0, 0 kg ha −1 ; N1, 90 kg ha −1 ; N2, 120 kg ha −1 ; N3, 150 kg ha −1 ; N4, 180 kg ha −1 ) and hill distance (HD) (HD1, 16.5 cm; HD2, 13.3 cm; HD3, 10 cm) on rice dry matter accumulation, translocation, and photosynthetic production in a split-plot experiment. At NARs below 120 kg ha −1 , the number of effective tillers increased significantly with increasing NAR and decreasing HD. The leaf area index (LAI) increased as the NAR increased and HD decreased and was the highest in the N4-HD3 treatment, followed by N3-HD3, at the full-heading stage. However, dry matter accumulation from the fullheading to the maturity stage was the highest in the N3-HD3 treatment. The population growth rate in N3-HD3 was the highest from the full-heading stage to the maximum grain-filling stage, at 26.46 g m −2 d −1 . The high rice yield under N3-HD3 conditions was attributed to the high dry matter accumulation after the full-heading stage and the high sheath output rate. This study revealed that treatment N3-HD3 resulted in high yield, from the perspective of photosynthetic matter production. INTRODUCTIONSoil salinity is an important limiting factor in agricultural production, currently affecting approximately 20% of the global arable land (Xia et al., 2019). China is one of the most seriously affected countries in the world, with large areas of