Prevention and Control of Continuous Cropping Obstacle of Watermelon by Reductive Soil Disinfestation (RSD)

强还原法防治西瓜连作障碍研究（英文）

This study aimed to explore whether reductive soil disinfestation（RSD） is an effective method of controlling continuous cropping obstacle of watermelon. Samples of watermelon continuous cropping soils were treated by RSD in laboratory tests and pot experiments in August 2015 and from December 10,2016 to April 10,2017. The soil samples for the laboratory test were divided into 16 groups,and each group comprised three parallel samples of 100 g（dry soil weight）. Except for the original and control（CK） samples,the 14 other groups of soil samples were treated with different combinations of 1% or 3% alfalfa powder,1% or 3% ammonia（NH3） water,and 1% or 3% acetic acid. The soil samples were placed inside size-five self-styled plastic bags and incubated in a constant-temperature biochemical incubator at 35°C for 14 days after blending,flooding,and sealing. Seven groups of soil samples were designed for the pot experiments based on the laboratory test results. Each group consisted of 30 parallel samples of 3 kg（dry soil weight）. These samples were incubated outdoors for 4 months after mixing with alfalfa powder and/or NH3 and/or acetic acid according to the experimental design,blending,flooding,and sealing. Watermelon seedlings were planted in the air-dried soil samples from May to July in 2017. The results showed that the p H of the soil samples treated by RSD were elevated except for those samples with acetic acid. In addition,the electrical conductivities of the soil samples treated by RSD were effectively adjusted. The presence of soil-borne pathogenic Fusarium oxysporum f.sp. niveum was significantly suppressed（p 0.05） in soil samples treated by RSD,and the incidence and mortality rate of watermelons planted in these samples were remarkably lower than those planted in the CK and flooded CK soil samples. Therefore,continuous cropping obstacle of watermelon can be controlled by RSD.

采用强还原土壤灭菌法(Reductive Soil Disinfestation,RSD)处理西瓜连作土壤,室内试验和盆栽试验相结合,探讨RSD防治西瓜连作障碍的有效方法。室内试验将西瓜连作土壤分设16组进行RSD处理,每组设3个平行样,每个土样折合干土重100 g,除原土样(OS)和对照(CK)外,其它14组处理分别按1%和3%两个比例添加苜蓿粉、氨水和乙酸,以及它们的不同组合,装入5号自封塑料袋内,混匀后加水,排空后密封,置于35°C恒温生化培养箱内培养14天,分析土样pH、电导率(Ec)、细菌、真菌、放线菌和致病尖孢镰刀菌(fusarium oxysporum f.sp.niveum,FON)等指标变化。RSD处理对土壤细菌含量影响不显著(p>0.05),添加氨水和乙酸处理的土样中均未检测出FON、真菌和放线菌,其它处理土样中FON数量显著低于OS和CK中FON(p<0.05);除添加有乙酸的土样pH低于5.0外,其它处理pH均高于OS和CK,其中添加氨水处理的土样pH最高。盆栽试验共设计7组,每组又分设30个平行样,每土样折合干土重约3 kg,除苜蓿粉用量为2%干土重外,氨水和乙酸均为干土重0.25%,各土样按设计添加物料、混匀、加水排空后密封,置于户外培养4个月,晾干后栽植西瓜直播苗,期间跟踪观察各处理西瓜长势及发病等情况,结果表明各处理发病率、死亡率显著低于对照和淹水对照,长势好于对照和淹水对照,产量显著高于对照和淹水对照(p<0.05)。可见,RSD能有效地调节土壤pH和Ec,抑制FON,防治西瓜连作障碍。