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Relatively low nitrogen (N) efficiency and heavy environmental costs caused by excessive N fertilizer applications with outdated fertilization techniques are current cultivation production problems with maize among smallholders in North China Plain. Although many studies have examined agronomical strategies for improving yields and N use, the integrated effects of these measures and the associated environmental costs are not well understood. We conducted a 2-year field study with two densities (67,500 plants ha-1, which was similar to local farmers’ practices, and 90,000 plants ha-1) and three N rates (0, 180, and 360 kg ha-1, the rate local farmers’ commonly apply) to test the integrated effects for maize production at Wuqiao experimental station in North China Plain. The higher planting density produced significant increases in grain yield (GY), N use efficiency (NUE), agronomic N efficiency (AEN), and N partial productivity (PFPN) by 6.6, 3.9, 24.7, and 8.8%, respectively; in addition, N2O emission and greenhouse gas intensity decreased by 7.3 and 4.3%, respectively. With a lower N application rate, from 360 to 180 kg ha-1, GY was unchanged, and NUE, AEN, and PFPN all significantly increased by 6.2, 96.0, and 98.7%, respectively; in addition, N2O emission and greenhouse gas intensity decreased by 61.5 and 46.2%, respectively. The optimized N rate (180 kg N ha-1) for the 90,000 plants ha-1 treatment achieved the highest yield with only 50% of the N fertilizer input commonly employed by local farmers’ (360 kg N ha-1), which contributed to the increased N-uptake and N-transfer capacity. Therefore, our study demonstrated that agronomical methods such as increasing planting density with reasonable N application could be useful to obtain higher GY along with efficient N management to help lower environmental costs of maize production.

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Field experiments were conducted in two seasons to investigate growth, physiology and yield responses of cabbage (Brassica oleracea L. cvs Pennant and Rio Grande) to deficit irrigation. In 2012 season, 50% of crop evapotranspiration (ETc) irrigation temporarily decreased plant size, reduced leaf area, fresh weight, relative water content, specific leaf area and gas exchange during late development, and decreased head fresh weight, size, marketable and total yield. Deficit irrigation at 75% ETc had little influence on plant growth and physiology, but it still reduced both marketable and total yield. In 2013 season, 75% ETc irrigation had little influence on plant growth, leaf characteristics, photosynthetic rate, head fresh weight and size, but it temporarily increased chlorophyll and carotenoid content, and decreased stomata conductance, transpiration, and marketable yield. Pennant, the green-head cultivar, had higher photosynthetic rate, head fresh weight, marketable and total yield than the red-head cultivar Rio Grande. In both seasons, deficit irrigations did not influence cabbage head dry weight, indicating that most yield reduction under deficit irrigations is related to water content.

The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a consequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affected by light deficiency. Therefore, two winter wheat (Triticum aestivum L.) cultivars, Tainong18 (a large-spike cultivar) and Jinan17 (a multiple-spike cultivar), were subjected to shading during anthesis and maturity under field condition in 2010-2011 and 2011-2012. Under the slight shading treatment (S1), leaf senescence was delayed, net photosynthesis rate (P n) and canopy apparent photosynthesis rate (CAP) were improved, and thus thousand kernel weight (TKW) and grain yield were higher as compared with the control. However, heavy-intensity shading (S2 and S3) led to negative effects on these traits substantially. Moreover, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity in flag leaf were significantly greater under slight shading than in other treatments, while the malondialdehyde (MDA) content was less than under other treatments. In addition, the multiple-spike cultivar is more tolerant to shading than large-spike cultivar. In conclusion, slight shading after anthesis delayed leaf senescence, enhance photosynthesis and grain filling, and thus resulted in higher grain yield.

The North China Plain (NCP) is one of the major areas of cereal production, and in recent years its maize (Zea mays L.) production has been influenced by both heat and chilling stresses. Adjusting the sowing date is an effective measure for mitigating these stresses. However, the underlying mechanisms remain poorly understood. We performed a 5‐year field experiment to determine how the sowing date mitigated heat and chilling stresses at Wuqiao Experimental Station in the NCP with three treatments: early sowing (ES), middle sowing (MS), and late sowing (LS). In all 5 years, higher grain yields were observed in the MS (averaged 11.7 Mg/ha) and LS (averaged 11.4Mg/ha) treatments compared with the ES (averaged 10.9Mg/ha) treatment. The lower yield in ES treatment mainly resulted from high temperature 5 days pre‐silking and 5 days post‐silking (>31.8°C). In 2015 and 2016, the lower grain yield in LS (11.4Mg/ha in 2015 and 11.2Mg/ha in 2016) treatment compared with MS (12.1Mg/ha in 2015 and 11.9Mg/ha in 2016) was mainly because the minimum temperature was <13.0°C 5 days before maturity or <13.6°C 10 days before maturity. Long‐term weather data further verified middle sowing would be appropriate in a changing climate. Therefore, we can conclude that sowing date manipulation constitutes a useful method for mitigating heat and chilling stresses for maize production.

Increasing planting density is one of the key management practices to enhance soybean yield. A 2-yr field experiment was conducted in 2018 and 2019 including six planting densities and two soybean cultivars to determine the effects of planting density on branch number and yield, and analyze the contribution of branches to yield. The yield of ZZXA12938 was 4389 kg ha−1, which was significantly higher than that of ZH13 (+22.4%). In combination with planting year and cultivar, the soybean yield increased significantly by 16.2%, 31.4%, 41.4%, and 46.7% for every increase in density of 45,000 plants ha−1. Yield will not increase when planting density exceeds 315,000 plants ha−1. A correlation analysis showed that pod number per plant increased with the increased branch number, while pod number per unit area decreased; thus, soybean yield decreased. With the increase of branch number, the branch contribution to yield increased first, and then plateaued. ZH13 could produce a high yield under a lower planting density due to more branches, while ZZXA12938 had a higher yield potential under a higher planting density due to the smaller branch number and higher tolerance to close planting. Therefore, seed yield can be increased by selecting cultivars with a little branching capacity under moderately close planting.