间作模式对社区花园可食植物生理特性及铅吸收的影响

Effects of intercropping patterns on physiological characteristics and Pb uptake of edible plants in community gardens

【目的】研究间作东南景天Sedum alfredii的社区花园受铅污染土壤中的植物生理特性及对重金属铅的吸收特征,以期筛选出降低可食植物对重金属铅吸收的最佳种植模式。【方法】以东南景天以及可食植物青芹Apium graveolens、上海青Brassica chinensis、辣椒Capsicum annuum和樱桃萝卜Raphanus sativus为研究材料,在浙江省杭州市临安区平山苗圃开展盆栽试验。以单作为对照,分析间作东南景天对可食植物生理生化指标的影响,以及可食植物的铅吸收转移特征、植物根际土壤pH和铅形态分布特征。【结果】(1)间作显著增加了东南景天、青芹和辣椒的生物量(P<0.05),降低了上海青和樱桃萝卜生物量;(2)东南景天和可食植物叶片内丙二醛浓度变化表现出一致规律,间作均低于单作;间作体系中青芹、辣椒、樱桃萝卜叶片内过氧化氢酶活性比单作分别显著增长33.92%、41.94%、53.80%(P<0.05);(3)间作东南景天显著降低了青芹、辣椒、樱桃萝卜可食部位对铅的积累(P<0.05),与单作相比分别下降了24.37%、162.50%和39.82%;(4)间作模式降低植物根际土壤pH,且改变土壤中铅形态分布。间作东南景天降低了可食植物根际土壤弱酸提取态铅和可氧化态铅的形态占比,提高了可还原态铅的形态占比。【结论】间作模式促进东南景天对铅的富集和迁移,减缓铅对可食植物的毒害作用。与东南景天间作,青芹、辣椒可食部位铅质量分数显著降低,达到安全食用标准;樱桃萝卜可食部位铅质量分数有降低的趋势。

[Objective]The objective is to study the physiological characteristics of plants in Pb contaminated soil and uptake characteristics of Pb in community gardens intercropped with Sedum alfredi,in order to screen out the best planting mode to reduce the uptake of Pb by edible plants.[Method]S.alfredii,Apium graveolens,Brassica chinensis,Capsicum annuum and Raphanus sativus were used as research materials.A pot experiment was carried out in Pingshan Nursery of Lin’an District of Hangzhou City,Zhejiang Province.The effects of intercropping S.alfredii on physiological and biochemical indexes of edible plants,uptake and transfer characteristics of Pb,the pH of rhizosphere soil and distribution characteristics of Pb were analyzed.[Result](1)Intercropping significantly improved the biomass of S.alfredii,A.graveolens and C.annuum,and reduced the biomass of B.chinensis and R.sativus(P<0.05).(2)The content of MDA in leaves of S.alfredii and edible plants showed a consistent pattern,and intercropping was lower than monoculture.In the intercropping system,CAT activities in leaves of A.graveolens,C.annuum and R.sativus significantly increased by 33.92%,41.94%and 53.80%,compared with the monoculture system(P<0.05).(3)Intercropping S.alfredii significantly reduced Pb accumulation in edible parts of A.graveolens,C.annuum and R.sativus,which decreased by 24.37%,162.50%and 39.82%,respectively(P<0.05),compared with monoculture.(4)Intercropping decreased the pH of rhizosphere soil and changed the distribution of Pb in soil.Intercropping S.alfredii decreased the form proportion of weak acid extracted and oxidized Pb in the rhizosphere soil of edible plants,but increased the form proportion of reducible Pb in soil.[Conclusion]The intercropping mode can promote the enrichment and migration of Pb in S.alfredii and reduce the toxic effect of Pb on edible plants.Intercropping S.alfredii significantly reduces Pb content in edible parts of A.graveolens and C.annuum,reaching the safe edible standard.The Pb content in edible parts of R.sativus tends to decrease,which is an ideal combination mode for intercropping restoration.