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The combination effects of nitrogen (N) fertilizer and planting density on maize yield, N use efficiency and the characteristics of canopy radiation capture and radiation use efficiency are not well documented in the Huanghuaihai Plain region in China. A 2-year field experiment was conducted from 2017 to 2018 in a split plot design with two N levels (240 and 204 kg N ha−1) applied to main plots and three plant densities (67,500, 77,625 and 87,750 plants ha−1) allocated to sub plots. Our results show that a 30% greater plant density combined with a 15% lower N rate (basal N) enhanced N partial factor productivity (NPFP) by 24.7% and maize grain yield by 6.6% compared with those of the conventional high N rate combined with a low density planting management practice. The yield increase was mainly attributed to significantly increased kernel numbers and biomass. The increased intercepted photosynthetically active radiation (IPAR) was the primary factor responsible for the high productivity of maize at increased planting density under reduced N conditions. The results indicate that increase planting density with reduced basal N application might benefit maize cropping for achieving high yields and sustainable development of agriculture.

Additional file 1: Table S1. Statistics of RNA-seq and short reads mapping. Table S2. Significantly varied GO terms between 158A and SGDH284 for line specific differentially expressed genes. Table S3. Statistics of differentially expressed transcription factors in 158A and SGDH284. Table S4. Enrichment analysis of cold responsive transcription factors in 158A and SGDH284. Table S5. Primer pairs used to detect the expression of selected transcription factors.

Waterlogging severely constrains wheat production after rice cultivation in the middle-lower reaches of the Yangtze River Plain, China. Raised bed planting (RBP) patterns may reduce waterlogging stress and increase wheat productivity. However, the physical mechanisms of resource use in wheat, particularly radiation resource use, are not well understood. The effects of planting patterns on the canopy structure, light interception (LI), intercepted photo synthetically active radiation (IPAR), radiation use efficiency (RUE) and yield of two wheat cultivars (Yannong 19 and Yangmai 25) were examined by employing two planting patterns, conventional flat planting (FP) and RBP, in 2018/19 and 2019/20. Relative to FP, RBP significantly increased wheat yield by increasing the IPAR and RUE of wheat. Yannong 19 and Yangmai 25 intercepted 4.57% and 7.14% more IPAR, respectively, averaged over the two years, under RBP than under FP. The significantly higher IPAR in RBP was ascribed mainly to the increased canopy leaf area index (LAI), and LI benefited from the improved early-season growth and delayed late-season leaf senescence, which compensated for the reduced cropping area under RBP caused by the furrows. The increased light penetration into the middle-lower canopy under RBP resulted in 1.82% and 3.55% higher RUE for Yannong 19 and Yangmai 25, respectively, compared with that under FP. The significantly higher IPAR caused by the delayed leaf senescence was the primary factor responsible for the high productivity of wheat under RBP. Our results suggest that the key factor that limits wheat production after rice cultivation is radiation capture during the critical growth period, which is low. This study suggests that RBP has promise for increasing productivity and radiation resource utilization.

Waterlogging stress is a major problem for wheat production in rice-wheat double cropping systems on the Yangtze River Plain in China and might become more frequent and intense due to global warming. To alleviate the profound impacts of waterlogging stress on wheat production, a raised bed planting (RBP) pattern was developed. The results showed that RBP significantly increased soil water drainage and reduced the soil water content. The reduced waterlogging stress promoted wheat seedling establishment and root growth, accelerated stem and tiller development, and delayed late-season root and leaf senescence, resulting in 11.3 % and 14.1 % higher grain yields in Fengtai and Guohe, respectively. Furthermore, RBP required fewer inputs and produced more outputs, generating 63.1 % and 59.6 % more net income in Fengtai and Guohe, respectively. Based on this study, RBP can be considered an effective, sustainable soil tillage practice to reduce waterlogging stress and thereby increase wheat productivity and profitability under future waterlogging conditions.