Cultivar (lines) and soil factors affecting wheat grain sulfur concentration in the major wheat-producing regions of China

Objectives The grain sulfur concentration (GSC) of wheat cultivars (lines) in China’s main production regions and the effects of year-round climate, cultivar and soil nutrient content on GSC were analyzed to understand the primary factors related to grain sulfur content.

Methods Local wheat cultivars were planted at 47 sites in dryland wheat regions (DW), wheat-maize regions (WM), and rice-wheat regions (RW). The wheat biomass, harvest index, yield and its composition, sulfur accumulation and distribution were investigated. Correlation analysis between grain sulfur concentrations of leading wheat cultivars (lines) and wheat biomass, harvest index, yield and its composition, and soil factors were analyzed.

Results The GSC of the main wheat cultivars in DW, WM, and RW was 1.73–2.27, 1.59–2.01, and 1.42–1.73 g/kg, respectively, with an average of 1.98, 1.78, and 1.53 g/kg. GSC in the same wheat regions was mainly affected by cultivar, site, and year. In dryland regions, cultivar had the highest contribution to GSC variation (13.1%). In contrast, the planting site recorded the highest contribution (34.2% and 52.0%) in wheat-maize and rice-wheat regions, respectively, followed by cultivars with 25.4% and 7.1% contribution rates. The effects of the harvest index and grain S absorption on wheat GSC were greater than yield components, the S harvest index, and aboveground S absorption. In dryland regions, the GSC showed a positive correlation with 1000 grain weight and aboveground S absorption but was negatively related to yield in wheat-maize regions. No significant relationship was recorded between GSC and yield but not the S harvest index. In rice-wheat regions, there was no relationship between GSC and 1000 grain weight and aboveground S absorption. GSC was positively correlated with grain N, P, Mg, Fe, Zn, and Mn concentrations in all three wheat regions but only correlated with K, Ca, and Cu concentration in several sites. In DW, the higher GSC of Yongshou wheat compared with Yangling may be due to the higher available soil phosphorus and sulfur concentrations in the former. GSC was positively correlated with soil Fe and Mn availability in WM; in RW, GSC was positively correlated with available Fe but negatively correlated with pH, available Zn, and available S.

Conclusions The main factor influencing wheat grain S content is cultivar. The soil nutrients have positive effects on grain S content, depending on the region. They are available P and S in the dryland wheat region; available Fe and Mn in the maize and wheat regions; and an available Fe concentration in the rice-wheat region.