铜、镉对三种豆科植物生长及氮磷钾含量的影响

Effects of copper and cadmium on leguminous plant growth and nutrient uptake.

为了解豆科植物在Cu、Cd单一污染土壤中的生长状况及对土壤养分的吸收利用特点,采用盆栽实验研究了Cu2+、Cd2+单一污染下紫花苜蓿、红三叶、沙打旺3种豆科植物的株高、根长、生物量和叶、茎部N、P、K、Cu和Cd含量的变化情况。Cu2+、Cd2+处理浓度分别为:0、400、800、1200mg.kg-1和0、1、10、20mg.kg-1。结果表明,3种豆科植物对Cu和Cd均有较强的吸收能力,除红三叶叶片中Cu含量外,3种豆科植物根、茎、叶中Cd和Cu的含量均与土壤中重金属添加量呈显著正相关。3种豆科植物在严重Cd2+污染的土壤中均能正常生长。在Cu2+添加量≤1200mg.kg-1时,红三叶能正常生长,而紫花苜蓿的生长则受到显著抑制作用,沙打旺在Cu2+添加量≥800mg.kg-1时生长受到抑制。土壤Cu2+添加量≤1200mg.kg-1时,能促进紫花苜蓿对N、P、K的吸收;Cu2+添加量≤800mg.kg-1时,对红三叶N、P、K含量没有明显影响;Cu2+添加量≤400mg.kg-1时,可提高沙打旺中N、P、K含量,但当Cu2+添加量≥800mg.kg-1时则显著降低。土壤Cd2+添加量≤20mg.kg-1时,对紫花苜蓿和红三叶茎叶以及沙打旺茎部的N、P、K含量有促进作用,但对沙打旺叶片的N、P、K含量起抑制作用。总体来看,3种豆科植物对Cu2+和Cd2+均有一定的耐性,红三叶对Cu2+的耐性较好,紫花苜蓿对Cd2+的耐性较好。

Aimed to understand the growthstatus and nutrient uptake of leguminous plants under soil copperor cadmium contamination, a pot experiment with Medicago sativa, Trifolium pretense, and Astragalus adsurgens was conducted, with their plant height, root length, plant biomass, and N, P, K, Cu and Cd contents in leaf and stem measured. The application amounts of Cu^2＋ and Cd^2＋ were 0,400, 800, and 1200 mg · kg^-1, and 0, 1, 10, and 20 mg · kg^-1, respectively. All the test three leguminous plants had strong capability of absorbing Cu and Cd. The Cu and Cd contents in their roots, stems, and leaves, except the Cu content in T. pratense leaf, were significantly positively correlated with the application amounts of Cu^2＋ and Cd^2＋. Under the application of Cd^2＋ , all the three leguminous plants grew normally. When the application amount of Cu^2＋ was ≤1200 mg · kg^-1, T. pratense grew normally, while the growth ofM. sativa was significantly inhibited. The growth of A. adsurgens was inhibited when the application amount of Cu^2＋ was ≥ 800 mg· kg^-1. An application amount of ≤1200 mg · kg^-1 of Cu^2＋ promoted the N, P and K absorption of M. sattva, but applying ≤ 800 mg · kg^-1 of Cu^2＋ had little effects on the N, P and K absorption of T. pretense. The N, P and K contents of A. adsurgens increased when the application amount of Cu^2＋ was ≤400 mg · kg^-1, but decreased sigmficantly Cd^2＋ when the Cu^2＋ application amount was ≥800 mg · kg^-1. When the apphcation amount of Cd was ≤20 mg· kg^-1 , the N, Pand K contents in M. sativa and T. pratense stems and leaves and in A. adsurgens stem increased, while those in A. adsurgens leaf decreased. As a whole, the three leguminous plants all had certain tolerance to Cu^2＋ and Cd^2＋ stresses, especially T. pratense to Cu^2＋ and M. sativa to Cd^2＋.