关键词: 袋控缓释, 桃, 氯化钾, 硫酸钾, 产量, 品质

Abstract:

【Objective】The effects of mixtures of potassium fertilizers being bag-controlled released on the photosynthesis, fruit yield and qualities of peach trees and the chloride content in soil were studied to provide reference for scientific application of potassium fertilizers in peach orchard.【Method】Late-ripening peach ‘Ruipan 21’/Prunus persica (Carr. ) Franch. were used as research materials, and a 2-year field trial was conducted with five types of fertilizers being bag-controlled released, including without potassium fertilizer (Control), 100% potassium sulfate (PC 0), 30% potassium chloride and 70% potassium sulfate (PC 30), 60% potassium chloride and 40% potassium sulfate (PC 60) and 100% potassium chloride (PC 100). It was fertilized at the beginning of March every year, the soil dynamic changes of available potassium and chloride content in 0-20 and 20-40 cm soil layer were determined in the middle of April, June, August and October of each year. The potassium and chloride content, SPAD values and photosynthetic rates in leaves were determined in the first rapid growth stage (S1), the hard core stage (S2), the second rapid growth stage (S3) and the maturity stage (S4) of peach trees, and the chloride content in fruit and the yield and qualities were investigated.【Result】The average Cl^- content in the 0-20 and 20-40 cm soil layer was 34.03 and 38.78 μg·g^-1 in the orchard without chlorine treatment. With the increase of potassium chloride, the Cl^- content in different soil layers showed an increasing trend. The average content of Cl^- in the 0-20 and 20-40 cm soil layer under PC 30, PC 60 and PC 100 were 37.98, 39.55, 41.61, 45.62, 51.17 and 58.87 μg·g^-1, respectively. However continuous application of bag-controlled potassium chloride for two years did not result in the accumulation of Cl^- in soil. The content of Cl^- in the leaves also increased with the increase of the amount of chlorine applied. The content of Cl^- under PC 30, PC 60 and PC 100 was 6.35%, 24.30% and 32.22% higher than that under PC 0. Among them, the content of Cl^- in the leaves of the four stages treated by PC 30 was 234.29, 243.16, 233.81 and 233.20 μg·g^-1, respectively. Moreover, PC 30 treatment significantly increased the SPAD value and net photosynthetic rate of leaves, while PC 60 and PC 100 treatment reduced the photosynthetic capacity of leaves. The content of available potassium in soil was higher in the early stage and decreased gradually later. The potassium release peak under PC 30, PC 60 and PC 100 treatments occurred in June, while the peak under PC 0 treatments occurred in August. The potassium content in the leaves reached the highest value in the second fruit growth stage (S 3), then decreased gradually, and the potassium content in the leaves at the maturity stage (S4) was the lowest. There was no significant change in the content of available potassium in leaves under different potassium treatments, indicating that the release rate of potassium chloride treatment had no significant effect on potassium absorption in leaves. The Cl^- content between PC 30 and PC 0 fruits had no significant difference, with an average content of 55.0 μg·g^-1. But the Cl^- content increased by 10.40% and 28.45% under PC 60 and PC 100, compared with PC 0 on average. For two consecutive years, the single fruit weight and yield treated with PC30 increased slightly, and which of PC 60 and PC 100 treatments were significantly reduced. The application of low potassium chloride had no significant effect on fruit quality, however medium or high potassium chloride could reduce the fruit quality.【Conclusion】Using the method of fertilizer being bag-controlled release, replacing potassium sulfate with 30% potassium chloride resulted in no accumulation of Cl^- in the soil, and could promote leaves photosynthesis, increase yield, and did not cause the decline of fruit quality and toxicity of the tree. Therefore, the proper amount of potassium chloride could be used instead of potassium sulfate in the peach orchard following the model of fertilizers being bag-controlled release.

Key words: bag-controlled release fertilizer, peach, potassium chloride, potassium sulfate, yield, quality