海南火龙果园土壤肥力与根结线虫数量调查

A survey of soil fertility and number of root-knot nematodes in dragon fruit orchards in Hainan

为了明确海南岛火龙果园土壤肥力状况和根结线虫危害情况,采集了海南岛68家火龙果园的土壤样品共204份,分析测定了土壤氮、磷、钾、钙、镁等矿质营养元素含量及根结线虫的数量,并采用模糊综合评判法对果园土壤综合肥力状况进行评价,分析了根结线虫数量与土壤养分状况的相关性。结果表明:海南岛火龙果园土壤pH为6.4,整体呈中性或弱酸性;有机质含量为19.9 g·kg^(-1),碱解氮含量为63.9 mg·kg^(-1),速效钾含量为95.8 mg·kg^(-1),均处于缺乏状态,而有效磷、交换性钙含量为丰富及以上等级,交换性镁处于中量水平;土壤pH与有机质、交换性钙、镁含量呈显著正相关,表明维持中性的pH水平有利于土壤有机质的积累,对钙、镁的有效性有重要意义;土壤有机质含量与碱解氮、有效磷、速效钾、交换性钙、镁含量呈显著正相关,说明土壤有机质的提高有助于提升土壤基础矿质养分的含量;各火龙果园根结线虫数量差异较大,其中,每100克干中土根结线虫2龄幼虫(J2)数量最多的可达736条,而较少的仅有14条;根结线虫发生轻重情况南北差异较大,整体上北部地区的火龙果园根结线虫数量低于南部地区;土壤pH、有机质、有效磷、交换性钙与根结线虫数量呈正相关。调查结果显示,海南岛火龙果园土壤综合肥力指数处于较高水平。

To clarify soil fertility and damage of root-knot nematodes in dragon fruit orchards in Hainan Island,a total of 186 soil samples were collected from 62 dragon fruit orchards,and the soil contents of nutrient elements such as nitrogen,phosphorus,potassium,calcium and magnesium,and the number of root-knot nematodes in the orchards were analyzed.The comprehensive soil fertility in the orchards was evaluated by using the fuzzy comprehensive evaluation method,and the correlation between the number of root-knot nematodes and soil nutrients was analyzed.The results showed that the average soil pH was 6.4 in the dragon fruit orchards,with the soil being generally neutral or weakly acidic in the orchards.The average soil content was 19.9 g/kg for organic matter,63.9 mg/kg for alkali-hydrolyzed nitrogen and 95.8mg/kg for available potassium content,all of which were in the state of deficiency.The soil contents of available phosphorus and exchangeable calcium were abundant or above,and the soil exchangeable magnesium content was in the medium level.The soil pH was positively correlated with the soil contents of organic matter,exchangeable calcium and magnesium,indicating that a neutral soil pH level was conducive to the accumulation of organic matter in the soil and had important significance for the availability of calcium and magnesium.The soil content of organic matter was positively correlated with the soil contents of alkali-hydrolyzed nitrogen,available phosphorus,available potassium,exchangeable calcium and magnesium,which indicated that the increase of soil organic matter would help to increase the contents of soil basic mineral nutrients.The number of root-knot nematodes in the dragon fruit orchards varied greatly.The maximum number of second-stage juveniles(J2)of root-knot nematodes in the orchards was 736 per 100 g dry soil,while the minimum number of the J2 root-knot nematodes was only 14 per 100 g dry soil.The incidence of the root-knot nematodes was different between the orchards in the north and the south of Hainan Island.On the whole,the number of the root-knot nematodes in the dragon fruit orchards was lower in the north than that in the south of Hainan Island.The soil pH and the soil contents of organic matter,available phosphorus and exchangeable calcium were positively correlated with the number of the root-knot nematodes in the soil.The findings of this survey showed that the comprehensive soil fertility index of the dragon fruit orchards in Hainan Island is at a high level.The changes of the soil pH and the contents of organic matter,available phosphorus and exchangeable calcium might have some reference for integrated management of the root knot nematodes in the dragon fruit orchards in Hainan.