外源草酸对钙质黄壤营养环境和刺梨苗生长及生理特性的影响

Effects of Exogenous Oxalic Acid on the Nutrient Environment of Calcareous Yellow Soil and the Growth,Physiological Characteristics of Rosa Roxburghii Seedlings

为探究外源草酸改善喀斯特地区石灰土营养环境和刺梨( Rosa roxburghii Tratt.)苗生长及生理特性的作用,以钙质黄壤和‘贵农5号’刺梨实生苗为材料,设置每kg土壤分别施入外源草酸5 mg、 25 mg和45 mg的3个处理的盆栽试验,研究了外源草酸的不同施用量对钙质黄壤有效养分含量、微生物种群结构、养分酶活性和对刺梨苗生长及相关生理特性的影响。结果显示:随外源草酸施入量的增大,钙质黄壤的pH值和交换性Ca、Mg的含量和放线菌的数量明显降低,有效N、P、K、Fe、Mn、Zn、Cu、B的含量明显增大,细菌、真菌和固氮菌、解磷菌解钾菌的数量明显增多,脲酶(Urase)、硝酸还原酶、Fe^ 3+铁还原酶和蔗糖酶的活性明显增强。在上述处理中,25 mg ·kg ^-1 草酸处理的钙质黄壤中碱性磷酸酶、蛋白酶和淀粉酶的活性最强,有效Fe、Zn、B的含量最高。另外结果还显示:施用外源草酸能够改善刺梨苗根系形态,降低Ca、Mg的吸收,对增强N、P、K、Fe,Mn,Cu,Zn和B的吸收和促进生长有明显的作用。25 mg ·kg^-1 草酸处理的植株生长高度、基径、生物量、根冠比值、根系总表面积、总体积、总根尖数都最大,N、P、K、Fe和Cu的吸收量最多,根系活力、Fe ^3+还原酶、谷氨酰胺合成酶和分泌性碱性磷酸酶的活性最强,与对照和其他处理的差异均达到显著水平(P<0.05)。根中硝酸还原酶和碱性磷酸酶的活性随外源草酸的施入量增加而增强。本研究表明,施入适量的外源草酸能够明显改善钙质黄壤的营养生态环境,对促进刺梨苗吸收N、P、K、Fe,Mn,Cu,Zn和B等营养元素和生长具有明显的作用,研究结果可为喀斯特地区钙质黄壤上刺梨栽培的养分及生长调控提供科学依据。

To investigate the effects of exogenous oxalic acids on the nutrient environment of calcareous soil and the growth and physiological characteristics of Rosa roxburghii seedlings. In this study, the calcareous yellow soil the ′Guonong 5′ Rosa roxburghii seedlings were taken as materials, and the pot experiments of three treatments as 5 mg, 25 mg and 45 mg exogenous oxalic acid per kg of soil were established to study the effects of different application rates of exogenous oxalic acid on the available nutrients content, the structure of microbial population, nutrient enzyme activity of the calcareous yellow soil, and the effects of these treatments on the growth and related physiological characteristics of Rosa roxburghii seedlings on the calcareous yellow soil. The results showed that, with the increasing applied amounts of exogenous oxalic acid, the pH value, exchangeable Ca and Mg contents and the number of actinomycetes were reduced significantly, and the contents of effective N, P, K , Fe, Mn, Zn,Cu, and B were significantly improved, the amounts of bacteria, fungi, azotobacter, phosphorus solubilizing bacteria and potassium -releasing bacteria were significantly increased, and the activities of urease, nitrate reductase, iron reductase and sucrase were enhanced significantly. of thezhree treatments, after applying 25 mg ·kg ^-1 oxalic acid on the calcareous yellow soil, the activities of alkaline phosphatase, protease and amylase,the contents of effective Fe, Zn, and B contents were the highest. Additionally, the results also showed that the exogenous oxalic acid has the effects of improving the root morphology, reducing absorption of Ca and Mg,enhancing absorption of N, P, K , Fe, Mn, Zn, Cu,Zn,B and promoting growth of the Rosa roxburghii seedlings. There were the highest growth height, base diameter, biomass, root/shoot ratio, total root surface area, total volume, total root tip, and the most absorption of N, P, K, Fe and Cu as well as, the activities of root activity, Fe^ 3+ reductase, glutamine synthetase and secreted alkaline phosphatase were the strongest in the treatments of 25 mg ·kg ^-1 oxalic acid, the differences from control and other two treatments reached significant levels (P<0.05). With the increasing of oxalic acid application amount, the activities of nitrate reductase and alkaline phosphatase were increased. Our study indicated that proper application of exogenous oxalic acid into calcareous yellow soil could significantly improve the soil nutrient ecological environment and promote absorption of N, P, K , Fe, Mn, Cu, Zn, B and growth of Rosa roxburghii seedlings, and these results could provide scientific basis for the nutrients and growth regulation of Rosa roxburghii cultivated on calcareous yellow soil of Karst area.