Abstract:

The content of mineral elements in soil, walnut leaves and fruits were tested under different soil mulching treatments to clarify the effects of soil mulching on fruit quality. ‘Jifeng’ walnut was used as the research material, three treatments of straw mulching (SM), ground cloth mulching (GCM) and natural grass mulching (NGM) were adopted, and bare earth was set as the control. The content of mineral elements in walnut leaves, walnut kernel and soil were measured by Inductively Coupled Plasma (ICP) instrument. And the phenotypic characteristics of walnut under the three treatments and control were measured. The results showed that there were significant differences in the content of K in soil among different treatments; the content of K after SM treatment was the highest, reaching 418.04 mg/kg on average, which was significantly higher than that of other treatments and control. And SM treatment could significantly reduce the content of Ca in soil. The K content in leaves under NGM treatment was the highest, reaching 9480.32 mg/kg on average, which was significantly higher than that of SM treatment and control. And there were significant differences in the content of Mn in leaves among different treatments, under SM treatment, the content of Mn reached 1670.78 mg/kg on average, which was significantly higher than that of other treatments and control. GCM treatment increased the content of Mg in walnut kernel, but it did not reach a significant level compared with the control. There were significant differences in the Mn content of walnut kernel among different treatments. Under SM and NGM treatments, the content of Mn in walnut kernel was the highest, reaching 385.84 mg/kg and 363.17 mg/kg on average respectively, which was significantly higher than that of GCM treatment and control. So was the content of Cu in walnut kernel. Under SM and NGM treatments, the content of Cu reached 16.45 mg/kg and 13.52 mg/kg on average respectively, especially under SM treatment, it was significantly higher than that under GCM treatment and control. SM treatment increased side diameter of fruit, which reached 53.85 mm on average, but it did not reach a significant level compared with the control. The thickness of shell decreased under NGM and SM treatments, reaching 1.78 mm and 1.87 mm on average respectively, especially under NGM treatment, it was significantly lower than that under GCM treatment and control. The kernel rate increased under both NGM and SM treatments, reaching 54.02% and 52.23% on average respectively, especially under NGM treatment, it was significantly higher than that under GCM treatment and control. In conclusion, NGM treatment can increase the kernel rate of nut, improve the content of trace elements in fruit and reduce the thickness of shell, so it is suggested to be popularized in production.

Key words: soil, mulching, walnut, quality, mineral element