Abstract
Plastic mulching (PM) is widely used to improve crop water use efficiency and grain yield, but few studies have reported the effects of PM on cereal crop quality, especially sulfur (S) nutrition of wheat, which has significant effects on grain protein content, dough rheology, baking quality and human health. To fill this knowledge gap, we conducted a multi-site field experiment on the Loess Plateau from 2014 to 2016 to study the effects of PM combined with nitrogen (N) fertilizer on grain yield, shoot S accumulation, and grain S concentration of winter wheat in dryland. Compared with no mulching (NM), PM increased grain yield by 13.7% but decreased grain S concentration, S requirement for 1,000 kg–1 grain, soil available S concentration, and post-anthesis S uptake by 9.0, 9.7, 24.4, and 51.8%, respectively. Plastic mulching significantly increased shoot S accumulation at anthesis by 19.2%, but there was no significant difference at maturity. Additionally, grain S concentration and S requirement had a linear-plateau relationship with N fertilization amount, reaching maximum values at 110 and 127 kg N ha–1 under PM, 37.5 and 27.0% higher than those under NM. Furthermore, shoot S accumulation and N application rates well-fitted the linear-plateau model at anthesis and maturity. At maturity, straw, grain, and shoots accumulated the most S at threshold N rates of 120, 85 and 110 kg N ha–1, respectively. Crucially, stem + leaf S concentration at anthesis had a significant linear relationship with grain S concentration under PM; a 1 g kg–1 increase in stem leaf concentration corresponded with a 0.24 g kg–1 increase in grain S concentration. This study’s findings suggest that combining soil S supplementation with optimal N fertilizer under PM in northwest China and other regions with similar cropping systems increases grain S concentration and improves nutritional and processing qualities.
Highlights
IntroductionSulfur (S) is an indispensable chemical element in the human body. Sulfur deficiency can cause frequent skin disease and alopecia and exacerbate the occurrence of blood glycosylation and cardiovascular diseases, threatening human health (Herr and Buchler, 2010; Ingenbleek and Kimura, 2013)
Every 100 kg N ha−1 increase in N fertilizer decreased the proportion of grain S contributed from vegetative organs by 9.3% but increased the proportion of grain S contributed from post-anthesis S uptake by 9.3% (Wang and Yu, 2007)
Grain S concentration and S requirement declined significantly under Plastic mulching (PM) compared to no mulching (NM), by 9.0 and 9.7% averaged across sites and years (Figures 2C,E and Supplementary Table 2)
Summary
Sulfur (S) is an indispensable chemical element in the human body. Sulfur deficiency can cause frequent skin disease and alopecia and exacerbate the occurrence of blood glycosylation and cardiovascular diseases, threatening human health (Herr and Buchler, 2010; Ingenbleek and Kimura, 2013). Sulfur metabolism in cereal crops is closely related to nitrogen (N) metabolism, with efficient cysteine synthesis requiring both N and S (Zörb et al, 2013; Carciochi et al, 2020). Every 10 kg ha−1 increase in shoot N in wheat varieties with high and moderate N/S ratios increased S accumulation by 1.1 and 1.6 kg ha−1, respectively (Wang et al, 2009). Under soil N deficiency, S remobilization in crop shoots can account for 39% of grain S accumulation (Wang et al, 2017). Increased N fertilizer significantly increased shoot S accumulation by 20.7–64.0% in wheat. Excessive N application does not increase root activity inhibiting root S uptake and reducing shoot S accumulation and grain S content (Wang and Yu, 2007; Xu et al, 2018)
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