不同大豆根茬比对连作番茄生长发育及根际土壤环境的影响

研究不同比例大豆根茬施入后对番茄连作土壤根际土壤酶活性、土壤微生物群落结构、土壤养分和番茄生长、产量及果实品质的影响,探索作物根茬对连作障碍的缓解作用机制。以非连作土壤(CK)、番茄8a连作土壤(CS)及连作土壤中掺入2%大豆根茬(CSS1)、1%大豆根茬(CSS2)、0.5%大豆根茬(CSS3)为处理,通过大棚盆栽试验,测定定植后14d、21d、28d、35d和42d的番茄株高、茎粗,定植前和果实膨大期测定根际土壤酶活性、土壤养分含量和开花坐果期的土壤微生物群落结构,并测定果实产量和品质。连作条件下,土壤过氧化氢酶、脲酶、蔗糖酶活性降低,碱性磷酸酶活性升高,施入大豆根茬后,土壤过氧化氢酶、脲酶、碱性磷酸酶、蔗糖酶活性都不同程度增加,CSS2处理的土壤脲酶、蔗糖酶、碱性磷酸酶活性显著高于CS处理;CSS1和CSS2处理的土壤细菌占总微生物数量比例、细菌/真菌的比值均不同程度增加,真菌数量和放线菌数量显著下降,其中CSS2处理的细菌数量、细菌/真菌的比值及总微生物数量显著高于CS;施入大豆根茬后,土壤全N、全P、全K、NO-3-N、NH+4-N、速效P、速效K的含量均有增加,以CSS1、CSS2处理的增加效果较明显;施入不同比例大豆根茬不同程度促进了番茄的茎粗生长;CSS2处理增加了果实可溶性糖和有机酸质量分数及番茄产量,降低了成熟果实硬度。综上所述,连作土壤内添入质量分数为1%的大豆根茬既能显著促进土壤酶活性提高,改善土壤微生物区系环境,促进土壤向细菌型转化,增加土壤养分质量分数,又能起到壮苗和提高番茄产量的效果。

Effects of Different Proportion of Soybean Stubble and Continuous Cropping Soil on Tomato Growth and Development and Rhizosphere Soil Environment

The effects of different proportion of soybean stubble on soil enzyme activities, soil microorganism community structures, soil nutrition, plant growth, quality of fruits and yield were evaluated in this experiment to explore the mechanism of soybean stubble reducing the continuous cropping obstacle. Five treatments had been included under greenhouse potted plant conditions: normal soil treatment(CK), continuous cropping obstacle soil (8 years) treatment(CS), continuous cropping soil mixed with 2% soybean stubble treatment(CSS1), continuous cropping soil mixed with 1% soybean stubble treatment(CSS2) and continuous cropping soil mixed with 0.5% soybean stubble treatment(CSS3). Plant height and stem diameter were measured in 14 d, 21 d, 28 d, 35 d and 42 d after planting. Rhizosphere soil enzyme activities, soil nutrition contents were measured in before planting stage and fruit formation stage. And soil microorganism community structures were measured in bloom and fruit set stage. Besides, fruits quality and yield were tested in fruit harvest stage. Results showed that compared with CK, rhizosphere soil catalase activities, urease activities, sucrase activities decreased in CS but phosphatase activities increased at the same time. Increases of soil catalase activities, urease activities, phosphatase activities and surcase activities were detected in CSS1, CSS2 and CSS3. And urease activities, sucrase activities and phosphatase activities in CSS2 were significantly higher than those in CS. Soil microbiological community analysis showed that mixing continuous cropping tomato soil with 2% or 1% soybean stubble had increased the proportion of bacterial quantity to total microbiological quantity and bacteria/fungi ratio. At the same time, CSS1 and CSS2 remarkably decreased the quantity of fungi and actinomycetes. Quantity of soil bacteria, total microorganisms and proportion of bacterial quantity to total microbiological quantity in CSS2 were significantly higher than other treatments. Fungal quantity had a dramatically decrease in CSS2, compared with CS. The CSS1 and CSS2 showed the better performance in soil nutrition contents of total nitrogen, total phosphorus, total potassium, NO^-₃-N, NH⁺₄-N, available phosphorus and available potassium than CS. CSS1, CSS2 and CSS3 had increased the plant stem diameter growth. It also can be clearly seen that the soluble sugar and organic acid contents of fruits, and the yield of tomato increased in CSS2. Meanwhile, fruit hardness decreased in this treatment. This study demonstrated that mixing continuous cropping soil with 1% ( mass fraction) soybean stubble significantly improved soil environment, soil microorganism community structures and increased soil nutrition. In addition, it can also increase the tomato plant growth and improve yield.