Effects of sorbitol and mannitol combined with NPK on the growth, fruit quality and nutrient absorption of peach

Abstract:【Objective】Sorbitol and mannitol are low- molecular- weight organic compounds. Studies have shown that sorbitol and mannitol promote the absorption of nutrients by plants, increase the utiliza-tion rate of fertilizers, improve fruit quality, and thus increase economic benefits. This study conducted a field experiment to explore the effects of sorbitol and mannitol combined with NPK fertilizer solution on the growth, fruit quality and nutrient absorption in peach. The study aimed to provide theoretical ba-sis for development of fertilizer formula for peach trees.【Methods】The experiment consisted of 2 field  trials, and Zhongtao 8 and Zhongyou 20 were used as the materials for the experiment. The application of water soluble NPK fertilizer was used as the control, and six treatments were set including sorbitol 2.5% plus NPK water soluble fertilizer (T1), sorbitol 5% plus NPK water soluble fertilizer (T2), sorbi-tol 10% plus NPK water soluble fertilizer (T3), mannitol 2.5% plus NPK water soluble fertilizer (T4),mannitol 5% plus NPK water soluble fertilizer (T5), and mannitol 10% plus NPK water soluble fertiliz-er (T6). The performance of peach tree growth, fruit quality and nutrient content in different treatments were measured.【Results】With the increase in the sorbitol concentration, the soluble solid content, sug-ar-to-acid ratio, and fruit N content decreased first and then increased; the chroma (C) showed an in-creasing trend, but the shoots length and K content in fruit showed a decreasing trend. In Zhongtao 8, compared with CK, the content of soluble solids in T1, T2, and T3 was significantly increased by 11.91%, 10.71%, and 14.08%, respectively. At the same time, T1, T2 and T3 increased the single fruit weight significantly, which were 22.3%, 20.4% and 16.70% larger compared with CK, respectively. In addition, the vitamin C content in T1 and T3 treatments increased significantly by 37.01% and 32.47%, respectively. And the treatment of T3 had the highest leaf fresh weight, which was significantly in-creased by 25.63% compared with CK. In Zhongyou 20, compared with CK, the soluble solids and sug-ar-acid ratio in T3 treatment were higher than T1 and T2, but the difference was not significant. The yield, C value, and CCI value in T3 were the highest and were significantly increased by 86.67% ,27.62%, and 58.14%, respectively, compared with CK. The P content in T1 treatment increased signifi-cantly by 31.19%. With the increase in the concentration of mannitol, the single fruit weight, soluble sugar and sugar-acid ratio increased first and then decreased. In Zhongtao 8, compared with CK, leaf fresh weight and sugar-acid ratio in T5 were significantly increased by 22.38% and 38.28%, respective-ly. In treatment of T6, single fruit weight, yield, titratable acid content, and CCI value were significantly increased by 18.05%, 30.29%, 25.58% and 49.07%, respectively, but the h° value was significantly re-duced by 23.96% . As for the fruit K nutrient content, T4 was significantly reduced by 16.61% . In Zhongyou 20, Among them, fruit weights in T4 and T5 were significantly increased by 8.43% and 6.66% compared with CK, respectively. T5 soluble sugar was significantly higher than CK, with an in-crease of 42.01%; T4, T6 and CK were not significantly different. At the same time, K contents in T5 and T6 were significantly increased by 8.21% and 6.51% compared with CK, respectively. In addition, C value in the treatments of T4 and T6 was significantly increased by 14.07% and 10.21%, respectively.The comprehensive ranking based on principal component analysis and membership function, the rank was T3> T6> T1> T5> T2> T4> CK in Zhongtao 8, and in Zhongyou 20 was T3> T5> T2> T1> T4> CK>T6.【Conclusion】The combined application of sorbitol and mannitol with NPK water soluble fertil-izer can promote the growth of peach trees, improve fruit quality, deepen the redness of the peach sur-face, improve the color of the fruit, and promote the absorption of nitrogen, phosphorus and potassium by the peach fruit. The combined application of sorbitol and mannitol with NPK water soluble fertilizer can significantly increase the fruit weight and soluble solid content of Zhongtao 8. The combination of 5% or 10% sorbitol with NPK water soluble fertilizer could significantly increase the yield, soluble sug-ar content and fruit color in Zhongyou 20 and the combined application of 2.5% and 5% sorbitol and NPK water soluble fertilizer promoted the P content uptake in Zhongyou 20 and Zhongtao 8. The com-bined application of 5% and 10% mannitol and NPK water soluble fertilizer increased K content in Zhongyou 20 fruit. Based on comprehensive analysis, the treatment with 10% sorbitol combined with NPK water soluble fertilize had best comprehensive effect.