木麻黄根区土壤理化特性及酶活性与青枯病发生关联分析

Correlation Analysis of the Occurrence of Bacterial Wilt and Physicochemical Properties and Enzyme Activity of Root-Zone Soil of Casuarina spp.

为探究木麻黄(Casuarina spp.)根区土壤理化特性及酶活性与青枯病发生的关系,进而为加强生物防治提供参考。选取位于广东省潮州市饶平县大埕镇、湛江市吴川市塘尾镇和湛江市徐闻县前山镇的3个木麻黄人工林为研究对象,在每个林分下分别设置3个样地,每个样地采集木麻黄青枯病感病植株和健康植株根区土壤各3份,共54个土壤样品,并测定部分土壤理化指标和酶活性。结果表明,饶平样地感病指数为1.33,吴川样地为5.47,徐闻样地为10.53。为了便于分析,根据感病指数将这3个研究样地进行青枯病发病等级的人为划分,由轻及重划分为饶平样地(1级)、吴川样地(2级)和徐闻样地(3级)。木麻黄青枯病感病植株根区土壤pH,土壤有机质(SOM)、全氮(TN)、全磷(TP)、全钾(TK)含量以及碱解氮(AN)、有效磷(AP)、速效钾(AK)含量均较健康植株低,且TN含量差异显著(P<0.05),SOM、AP、TK、AK和AN含量差异极显著(P<0.01)。木麻黄健康植株根区土壤脲酶(URE)、酸性磷酸酶(ACP)、过氧化氢酶(CAT)、过氧化物酶(POD)以及多酚氧化酶(PPO)活性均高于感病植株;而蔗糖酶(INV)活性低于感病植株。此外,木麻黄青枯病发病等级与土壤中TK含量和AP含量呈极显著负相关关系(P<0.01),与PPO活性呈极显著正相关关系(P<0.01),与ACP、INV、CAT、POD活性均呈负相关关系。不同发病等级土壤PPO活性分别为:1级23.45mg·g^(-1)·h^(-1)、2级30.43 mg·g^(-1)·h^(-1)、3级59.63 mg·g^(-1)·h^(-1)。综上,PPO活性可以作为反映木麻黄感染青枯病程度的酶学指标。土壤理化特性和酶活性对木麻黄起到的抗病机理是复杂的,仍需进一步从分子和生理水平上进行研究和考证;探究其抵御木麻黄青枯病的最适浓度,研究与其他元素的作用,将多种元素结合协同发挥作用。从土壤微生物角度,与生防菌协同预防植物病害的发生是未来可研究的方向。

In order to investigate the relationship between the occurrence of bacterial wilt in Casuarina spp. forest and soil physicochemical properties and enzymatic activity, this study selected diseased and healthy plants of Casuarina spp. from Dacheng Town, Raoping County, Chaozhou City of Guangdong Province, Tangwei Town, Wuchuan City and Qianshan Town, Xuwen County of Zhanjiang City. A total of 54 soil samples were collected and the physicochemical properties and enzyme activity in the soil were measured. The results showed that the disease index was 1.33 in Raoping, 5.47 in Wuchuan, and 10.53 in Xuwen. As part of the data analysis, the three sampling plots were classified according to the disease index, from light to severe, as Raoping plot(level 1), Wuchuan plot(level 2), and Xuwen plot(level 3). Soil pH value, SOM, TN, TP, TK, AN, AP, and AK content in the root-zone of diseased plants of Casuarina spp. were lower than those of healthy plants. There were significant differences in TN contents(P<0.05), and the differences in SOM, AP, TK, AK and AN contents were highly significant(P<0.01). The contents of URE, ACP, CAT, POD and PPO in the roots of healthy plants of Casuarina spp. were higher than those in diseased plants. The the contents of INV in the root had highly significant negative correlations with the TK and AP content in the soil(P<0.01), and highly significant positive correlation with the content of PPO(P<0.01), and negatively correlations with ACP, INV, CAT, and POD activity. The soil PPO activity of different disease degrees were as follows: level 1(23.45 mg·g^(-1)·h^(-1)), level 2(30.43 mg·g^(-1)·h^(-1)), and level 3(59.63 mg·g^(-1)·h^(-1)). In summary,PPO activity can be used as an indicator of the degree of bacterial wilt infection of Casuarina spp.. The mechanism of soil physicochemical properties and enzymatic activity against bacterial wilt is complex and thus needs to be further investigated. Future studies may prove it at the molecular and physiological levels, explore its optimal concentration to resist bacterial wilt, take into account other elements, and examine combined effects of multiple elements. From the perspective of soil microbes, future research should examine the prevention of plant diseases in collaboration with biocontrol bacteria.