草酸对刺梨立地石灰性土壤及叶片养分和果实产量、品质的影响

Effects of oxalic acid on the nutrient of calcareous cultivated soil and leaf,fruit yield and quality of Rosa roxburghii Tratt.

【目的】探究外源草酸对喀斯特地区刺梨栽培的石灰性黄壤及树体营养状况和果实产量、品质的影响,为应对石灰性土壤对刺梨的养分胁迫和提高其果实产量、品质寻找新的技术路径。【方法】以石灰性黄壤上种植的3年生贵农5号刺梨为材料,连续3 a(年)进行每株0(对照)、5、10、15 g的草酸施入量处理。【结果】施用草酸能够明显降低刺梨立地石灰性黄壤的pH值和交换性Ca的含量,增加其他营养元素的有效含量,增强土壤脲酶、硝酸还原酶、碱性磷酸酶、铁还原酶、蛋白酶的活性,增加三大微生物种群及固氮菌、解磷菌、解钾菌的数量,提高叶片中除Ca以外的营养元素的含量,能够明显提高刺梨果实的产量及可溶性固形物、可溶性总糖、维生素C的含量,其中,以每株施用10 g草酸处理的效果最好。【结论】施用草酸能够增强喀斯特地区刺梨立地石灰性黄壤的养分酶活性和有效氮、磷、钾、铁、锌、硼等营养元素的有效性,改善土壤微生物种群结构,增加土壤和树体的养分含量,对提高刺梨的产量、品质有明显作用。

【Objective】Rosa roxburghii Tratt.is a characteristic fruit tree native to southwest China.Its fruit is rich in Vc and other nutrients,and is a high-quality crude material for processing nutritious foods.In recent years,the planting area of R.roxburghii in Guizhou increased to 150000 hectares,and most of the trees were planted in calcareous yellow soil with high Ca content and soil pH value in Karst areas.Such soil conditions have extremely adverse effects on the growth,yield and quality of R.roxburghii due to low the availability of soil nutrients as a result of the strong immobilization of soil nutrients by massive free CaCO3.It is also difficult to improve soil nutrients by fertilization.Therefore,it is an important problem to be solved urgently in production of R.roxburghii in calcareous yellow soil of Karst areas.The effects of exogenous oxalic acid in improving the nutrient status of calcareous yellow soil and trees of R.roxburghii as well as the yield and quality of fruit were explored in this study in order to find a new technical solution for nutrition improvement as well as yield and quality improvement in R.roxburghii in calcareous yellow soil in Karst areas.【Methods】Trees of R.roxburghii Tratt.‘Guinong 5’planted in the calcareous yellow soil in Karst area of Southwest Guizhou were taken as materials.The experiments were carried out for three consecutive years to study the effects of oxalic acid application at different applied amounts(0 g,5 g,10 g and 15 g per plant)on the nutrient status of calcareous yellow soil and the leaf of R.roxburghii,as well as on fruit yield and quality.【Results】The pH value and Ca content could be decreased greatly by the application of oxalic acid.The soil pH decreased from 8.13 to 7.49,6.93 and 6.54 by applying 5 g,10 g and 15 g oxalic acid per plant,respectively,while the content of exchangeable Ca decreased from 3108.25 mg·kg-1 to 2410.76 mg·kg-1,1906.39 mg·kg-1,and 1353.88 mg·kg-1,respectively.Compared with the control,the activities of urease,nitrate reductase,alkaline phosphatase,Fe3+reductase and protease in the soil were significantly higher;the contents of available nutrient elements except for exchangeable Ca were also increased;the number of bacteria,fungi,actinomycetes,azotobacters,inorganic phosphorus bacteria,organic phosphorus bacteria and potassium bacteria increased as well.In the three treatments,application of 10 g oxalic acid per plant had the highest contents of available N,P,K,Fe and B in the soil,highest activities of urease,nitrate reductase,alkaline phosphatase and Fe3+reductase,and maximum numbers of functional bacteria.With higher oxalic acid applied,the contents of exchangeable Mg and available Mn,Cu and Zn in the soil increased.The contents of N,P,K,Mg,Fe,Mn,Cu,Zn and B in the leaves of R.roxburghii treated by oxalic acid were significantly higher than those in the control,and the treatment of 10 g oxalic acid per plant had the highest contents of N,P,K,Fe,Zn and B in the leaves.With the increase in application amount,Ca content in the leaves decreased significantly but Cu content increased dramatically.Fruit set,single fruit weight,fruit yield per plant and contents of soluble solids,total soluble sugars,total acids and Vc in the fruit were also increased by applying oxalic acid.The highest yield and best quality were obtained by the treatment of 10 g oxalic acid per plant.【Conclusion】The application of oxalic acid could significantly improve the contents of available nutrients in the yellow calcareous soil in Karst areas,and improve the microbial population structure in the soil,increase the activities of nutrient enzymes in the soil,and increase leaf nutrient and fruit yield and quality.In the experiment,applying 10 g oxalic acid per plant proved to be the most effective in increasing the fruit yield and quality of R.roxburghii grown in the calcareous soil.