土层置换对连作土壤微生物及再植幼苗的影响

Effects of soil layer replacement on continuous cropping soil microorganisms and replanted seedlings

试验旨在探讨土层置换对连作再植幼苗生长及土壤微生物的影响,为老果园更新提供理论依据。以蒙阴、莱州和栖霞三地25年生苹果园土壤、平邑甜茶幼苗和苹果嫁接苗为试验材料,设置定植沟原位回填(CK)和上下土层置换(SLR)2个处理,测定不同处理对幼苗生物量、蒸腾速率、净光合速率、气孔导度、胞间CO_(2)浓度、土壤微生物数量和土壤阳离子交换量的影响,并使用实时荧光定量技术检测土壤中主要有害真菌的数量变化。结果表明,与定植沟原位回填(CK)处理相比,上下土层置换后,显著促进了再植幼苗的生物量;蒙阴9月数据结果表明,上层土置换到下层后(MSLRA),土壤真菌数量降低了28.1%,土壤细菌数量增加了38.1%;下层土置换到上层后(MSLRB),土壤真菌数量降低了37.1%,土壤细菌数量增加了31.3%,且土层置换处理后显著增加了三地果园各层土壤的细菌/真菌值,降低了土壤中4种有害镰孢菌的基因拷贝数,优化了土壤微生物群落结构;同时显著提高了植株叶片的蒸腾速率、净光合速率、胞间CO_(2)浓度和土壤阳离子交换量。综上,土层置换措施可有效减轻老龄苹果园连作障碍。

The experiment was to explore the effects of the soil layer replacement on growth and soil microorganisms of replanted seedlings,and to provide a theoretical basis for the renewal of old orchard.The experimental site was selected from the 25-year apple orchard soil in Mengyin,Laizhou and Qixia,and the Malus hupehensis Rehd.seedlings and YanFu3/M9T337 apple grafted seedings were taken as the material.Two treatments were set up,which were CK(engraftment ditch of in-situ backfill)and SLR(soil layer replacement).The effects of the soil layer replacement on growth,transpiration rate,net photosynthetic rate,stomatal conductance,intercellular carbon dioxide concentration,soil microorganisms and soil cation exchange capacity were studied.The number of the Fusarium sp.was detected by a real-time quantitative PCR detection system.The results showed that treatment with SLR significantly promoted the growth of replanted seedlings than CK.The results of the data of Mengyin in September showed that the number of soil fungi decreased by 28.1%and the numbers of soil bacteria increased by 38.1%after the upper soil was replaced by the lower soil(MSLRA);the number of soil fungi decreased by 37.1%and the numbers of soil bacteria increased by 31.3%after the lower soil was replaced by the upper soil(MSLRB);the bacterial/fungi ratio of each layer of soil in the three ochards was increased significantly,the gene copy number of four harmful Fusarium sp.was reduced significantly,indicating that the structure of soil microbial community was optimized;The leaf transpiration rate,net photosynthetic rate and intercellular carbon dioxide concentration were increased.At the same time,the change of soil environment significantly increased the soil cation exchange capacity after the upper soil was replaced by the lower soil.In conclusion,the soil layer replacement can effectively alleviate the continuous cropping obstacles of aging apple orchards.