ABSTRACT
To study the sources and potential risks of heavy metals in soils of characteristic agricultural product producing areas is of great significance for the scientific management and safe utilization of soil and crop resources. The contents of heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the 254 surface soil samples collected from the Heze oil peony planting area were determined. The content characteristics and correlation of heavy metals were analyzed using multivariate statistical methods. The sources of heavy metals in topsoil were analyzed using Igeo, PMF, and PCA/APCS. The ecological risks of the eight heavy metals were assessed through the potential ecological risk index (PERI). The results showed that the average contents of seven heavy metals in the soil were basically consistent with the background values of soil elements in Heze City, except that the average value of Cd was 1.44 times higher than the background value in Heze City. Correlation analysis and cluster analysis revealed that Pb, Hg, and Cd elements in the soil were greatly affected by human activities in the later period. The sources of eight heavy metals in the study area were natural sources, agricultural fertilizer sources, industrial coal sources, and domestic transportation sources, with the contribution rates of 81.31%, 15.45%, 2.74%, and 0.50%, respectively; 84.25% of the sites in the study area were at slight ecological risk, whereas the moderate risk and strong risk sites accounted for 14.96% and 0.79%, respectively. Among them, Cd and Hg were the dominant elements of ecological risk in the study area.
ABSTRACT
In order to clarify the mechanisms underlying dryland wheat quality improvement through sowing technology, the effects of wide space sowing (WSS), furrow sowing (FS), and drill sowing (DS) on soil moisture dynamics and grain protein formation in dryland wheat field were studied in Wenxi, Shanxi Province in 2017-2018 (normal year) and 2018-2019 (dry year). The results showed that compared with the DS, FS significantly increased soil water storage in the 0-200 cm depth at anthesis stage (8.2%-18.7%), and increased the soil water storage in 0-60 cm layer during the two years, 60-120 cm layer in normal year, and 120-200 cm layer in dry year. WSS significantly increased soil water storage in 0-200 cm layer at anthesis stage in normal year (5.2%). Compared with DS, FS significantly increased water consumption of anthesis to mature stage, while WSS significantly increased water consumption from sowing to anthesis stage in dry year. Compared with DS, the glutamine synthetase (GS) activity of grains at 15-35 days after anthesis was significantly increased by FS and WSS, while the glutamate synthase (GOGAT) activity of flag leaves and grains at 5-35 days after anthesis was significantly increased by FS in the dry year. Compared with DS, FS significantly increased grain yield by 20.4%-44.8%, grain protein yield by 25%-49%, and increased grain albumin and globulin contents. WSS significantly increased grain yield by 9%-40%, and increased grain gliadin content. Under different sowing modes of dryland wheat, GS and GOGAT activities in flag leaves and grains after anthesis were significantly correlated with water consumption at anthesis to maturity stage. There were significant correlations between GS and GOGAT activities in flag leaves and grains and 0-120 cm soil layers in the normal water year, and between GS and GOGAT activities and 0-60 cm, 120-200 cm soil layers in the dry year. The contents of grain albumin, globulin and total protein were significantly correlated with soil water storage in 0-60 cm layer at anthesis stage, as well as soil water storage in 120-200 cm layer at anthesis stage in the dry year. In conclusion, FS was beneficial to increasing soil water storage at anthesis and water consumption after anthesis of dryland wheat, improving GS and GOGAT activities of flag leaf and grain, with positive consequences on yield and grain protein content. In addition, deep water storage was more conducive to quality improvement in the late growth period in the dry year.
