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研究在苹果连作土壤中添加甲壳素对苹果幼苗生长、土壤酶及土壤真菌群落结构的影响,探讨甲壳素缓解苹果连作障碍的可能性,为防控苹果连作障碍提供依据。盆栽条件下,以平邑甜茶幼苗为试材,在苹果连作土壤中分别添加0,0.5,1.0和2.5g/kg的甲壳素,测定了连作土壤中添加不同量的甲壳素后,幼苗生物量、根系保护酶活性、土壤主要酶(蔗糖酶、脲酶、磷酸酶等)活性以及土壤中真菌群落结构的变化。9月份结果表明,与对照相比,1.0 g/kg的甲壳素处理连作土,可显著提高平邑甜茶幼苗株高和干鲜重,分别比对照增加了36.8%、82.1%和100.8%;甲壳素处理能增加幼苗根系保护酶活性,其中1.0 g/kg甲壳素处理SOD、POD和CAT活性最高,其次为0.5 g/kg,而2.5 g/kg甲壳素处理显著抑制了幼苗根系保护酶活性。1.0 g/kg甲壳素处理可提高土壤中细菌/真菌值,并且提高了土壤中蔗糖酶、脲酶、蛋白酶、磷酸酶、过氧化氢酶和多酚氧化酶活性,分别比对照提高了8.6%、40.5%、81.1%、15.3%、18.7%和49.8%,2.5 g/kg甲壳素处理则降低土壤酶活性或者使土壤酶活性与对照相当。根据T-RFLP的图谱中OUT的数量、种类及丰度,分别计算了不同处理土壤的真菌多样性,发现1.0 g/kg甲壳素处理的连作土具有最高的多样性、均匀度和丰富度指数,分别比对照增加了52.2%、8.0%和87.1%。主成分分析(PCA)结果显示,不同剂量甲壳素处理的连作土壤中真菌被PC2分成了两部分,其中0.5 g/kg和1.0 g/kg的甲壳素添加量分布在PC2的负方向上,而CK和2.5g/kg的甲壳素处理分布在PC2的正方向上,这说明添加不同量的甲壳素对连作土壤真菌群落多样性有显著影响,添加量太多或者太少均会造成土壤真菌多样性下降,只有适量的甲壳素可提高真菌群落结构多样性。实验结果表明1.0 g/kg的甲壳素可提高连作平邑甜茶幼苗生物量,改善连作土壤环境,有效缓解平邑甜茶的连作障碍。
To study the effects of adding chitin on the growth of apple seedlings, soil enzymes and soil fungal community structure in apple continuous cropping soils, and to explore the possibility that chitin could alleviate the continuous cropping obstacles and provide the basis for prevention and control of crop continuous cropping obstacles. Under the condition of pot culture, the seedlings of Hippophae rhamnoides L. were treated with 0, 0.5, 1.0 and 2.5g / kg chitin respectively in continuous cropping soil. After adding different amounts of chitin in continuous cropping soil, the seedling biomass , The activities of protective enzymes in roots, the activity of major enzymes in soil (sucrase, urease, phosphatase, etc.) and the changes of fungal community structure in soil. The results in September showed that the 1.0 g / kg chitin treatment could increase the plant height and dry weight of the seedlings significantly, which were 36.8%, 82.1% and 100.8% higher than that of the control respectively. The treatment with 1.0 g / kg chitin had the highest activity of SOD, POD and CAT, followed by 0.5 g / kg, while the treatment with 2.5 g / kg chitin significantly inhibited the activity of protective enzyme in roots of seedlings. The 1.0 g / kg chitin treatment increased the bacterial / fungal values in the soil and increased the activities of sucrase, urease, protease, phosphatase, catalase and polyphenol oxidase in the soil by 8.6% 40.5%, 81.1%, 15.3%, 18.7% and 49.8%, respectively. Chitin treatment at 2.5 g / kg reduced soil enzyme activity or caused soil enzyme activity to be comparable to that of the control. According to the number, type and abundance of OUT in T-RFLP map, the fungal diversity of different treatments was calculated. The highest diversity, evenness and richness index of 1.0-g / kg chitin-treated silt soil were found Respectively, increased by 52.2%, 8.0% and 87.1% respectively compared with the control. The results of principal component analysis (PCA) showed that the fungi in continuous cropping soil with different doses of chitin were divided into two parts by PC2. The addition of 0.5 g / kg and 1.0 g / kg of chitin distributed in the negative direction of PC2 Chitin treatment with CK and 2.5g / kg distributed in the positive direction of PC2, indicating that adding different amounts of chitin has a significant effect on the diversity of soil fungal communities, and too much or too little addition of soil fungal diversity Decline, only the appropriate amount of chitin can improve the diversity of fungal community structure. The results showed that 1.0 g / kg of chitin could improve the biomass of continuous Eupolyphaema chinensis seedlings and improve the continuous cropping environment so as to effectively alleviate the continuous cropping obstacle.