设施蔬菜栽培茬口对生态型无土栽培基质性状变化的影响

Effect of different rotation systems on the characteristic change of ecotype soilless culture media for vegetables in greenhouse environments

以设施番茄生态型无土栽培正茬、迎茬、连茬基质为试材,研究了不同茬口对设施番茄根圈基质酶活性和理化性状的影响。结果表明,番茄正茬栽培基质的绝对含水量、蔗糖酶和脱氢酶活性最高,多酚氧化酶活性最小;连茬基质的纤维素酶和多酚氧化酶活性最高,容重和酸碱度(pH值)最大。基质酶活性与理化性质的相关性分析表明,番茄无土栽培中,连茬、迎茬和正茬条件下基质的化学性质与生物学性状是密切相关的,从而导致了番茄连茬基质微生态环境的改变,最终导致产生连作障碍。所有指标的相关性中,脱氢酶活性与理化性质的相关性较差,蔗糖酶、多酚氧化酶和纤维素酶活性与理化性质的相关性较好,说明蔗糖酶、多酚氧化酶和纤维素酶活性是影响基质pH值、电导率(EC)和物理性质的重要因素。正茬基质的容重、总孔隙度和通气孔隙度的可塑性指数均最大,蔗糖酶活性、pH值和持水孔隙度的可塑性指数均最小;连茬基质的脱氢酶、多酚氧化酶、纤维素酶、绝对含水量、总孔隙度、通气孔隙度、大小孔隙比的可塑性指数均最小,说明正茬基质比连茬基质具有更广泛的环境适应性,更能适应番茄根系不同分泌物的累积。各茬口基质的大小孔隙比、通气孔隙度、脱氢酶和绝对含水量的可塑性指数均较大,能较其他指标更好地反映不同茬口基质的优越性。综合分析表明,不同茬口基质生物、理化性状的优越性表现为:正茬>迎茬>连茬;设施生态型无土栽培番茄连茬严重破坏了基质的生物和理化性状,正茬栽培对基质生物、理化性状的影响较小。

With the development of ecological agriculture and sustainable circular agriculture, greenhouse tomato plants develop rapidly in organic media culture. However, due to plant habitat requirements and reduction of production costs, the reuse of the cultivation medium has become common. As reuse increases, the influence that diseases and pests have increases, which decrease the yield and quality of fruits and impacts both the physical and chemical character, and so on. This becomes a major bottleneck that restricts the sustainable development of the greenhouse tomato in organic media culture. Self allelopathy is one of the most important obstacles to continuous cropping, commonly found in protected vegetable cultivation. Therefore, in protected tomato cultivation systems, the biological character and physicochemical character have an important theoretical and practical significance when exploring different enzyme activities in cropping rotation organic ecotype soilless culture media. This paper studied the effects of three cropping rotations （i.e. normal cropping, alternate cropping and continuous cropping） on the ellulase activity, polyphenol oxidase activity, invertase activity, dehydrogenase activity and pH, electrical conductivity and physical properties of the greenhouse tomato rhizosphere matrix in soilless culture. The results showed that substrate enzyme activities and pH, electrical conductivity and physical properties were strongly affected by the different cropping rotations. The absolute water content, invertase activity and dehydrogenase activity were the highest in normal cropping matrix and the polyphenol oxidase activity was the lowest. However, in the continuous cropping matrix, the substrate ellulase activity and polyphenol oxidase activity were the highest and substrate bulk density and pH were the largest. In soilless culture, the chemical properties in the substrate are closely related to the physical properties under normal cropping, alternate cropping and continuous cropping, leading to a change of micro-ecological environment, and finally resulting in continuous cropping obstacles. There was a poor correlation between dehydrogenase activity and the physical and chemical properties, but there were significant correlations of ellulase activity, polyphenol oxidase activity and invertase activity with the physical and chemical properties, which leads to a conclusion that the activities of sucrase, polyphenol oxidase and cellulase were the main factors influencing the pH, electrical conductivity and physical properties of the matrix. Under normal cropping, the plasticity index of the substrate, bulk specific gravity, total porosity and aeration porosity were statistically the greatest in all indexes, but the activities of dehydrogenase, polyphenol oxidase, fiber luciferase, absolute water content, total porosity, aeration porosity and void ratio plasticity indexes were the lowest when the tomato was continuously cropping. This leads to a conclusion that the normally cropped matrix has a very good and more extensive environmental adaptability than the succession cropping stubble. The plasticity index, void ratio, aeration porosity, dehydrogenase activity and absolute water content in all crops for rotation were greatest. Therefore, the void ratio, aeration porosity, dehydrogenase activity and absolute water content can be used to evaluate advantages of biological and physicochemical parameters in different rotation matrices. The observed results indicated that the different crops used for rotation have advantages as follows： normal cropping〉alternate cropping〉continuous cropping. Continuous cropping caused severe damage to the enzyme activity, biological and physicochemical characteristics of the matrix, while normal cropping has little effect on its biological and physicochemical parameters.