铜、镉对三种豆科植物生长及氮磷钾含量的影响

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Cu~(2+)、Cd~(2+)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.Cu~(2+)、Cd~(2+)处理浓度分别为:0、400、800、1200 mg·kg~(-1)和0、1、10、20 mg·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Cd~(2+)污染的土壤中均能正常生长.在Cu~(2+)添加量≤1200 mg·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Cu~(2+)添加量≥800 mg·kg~(-1)时生长受到抑制.土壤Cu~(2+)添加量≤1200 mg·kg~(-1)时,能促进紫花苜蓿对N、P、K的吸收;Cu~(2+)添加量≤800 mg·kg~(-1)时,对红三叶N、P、K含量没有明显影响;Cu~(2+)添加量≤400 mg·kg~(-1)时,可提高沙打旺中N、P、K含量,但当Cu~(2+)添加量≥800 mg·kg~(-1)时则显著降低.土壤Cd~(2+)添加量≤20 mg·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Cu~(2+)和Cd~(2+)均有一定的耐性,红三叶对Cu~(2+)的耐性较好,紫花苜蓿对Cd~(2+)的耐性较好.

Abstract：

Aimed to understand the growth status and nutrient uptake of leguminous plants under soil copper-or cadmium contamination, a pot experiment with Medicago sativa, Trifolium pre-tense, and Astragalus adsurgens was conducted, with their plant height, root length, plant bio-mass, 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), re-spectively. 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. Pratease leaf, were significantly positively correlated with the application amounts of Cu~(2+) and Cd~(2+). Un-der the application of Cd~(2+), all the three leguminous plants grew normally. When the application amount of Cu~(2+) was≤1200 mg·kgM-1, T. Pratense grew normally, while the growth of M. Sativa was significantly inhibited. The growth of A. Adsurgens was inhibited when the application amount of Cu~(2+) was≥800 mg·kg~(-1). An apphcation amount of≤1200 mg·kg~(-1) of Cu~(2+) pro-moted the N, P and K absorption of M. Sativa, 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 in-creased when the application amount of Cu~(2+) was ≤400 mg·kg~(-1), but decreased significantly when the Cu~(2+) application amount was≥800 mg·kg~(-1). When the application amount of Cd~(2+)was≤20 mg·kg~(-1) , the N, P and 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. Prat-ease to Cu~(2+) and M. Sativa to Cd~(2+).

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

Aimed to understand the growth status and nutrient uptake of leguminous plants under soil copper-or cadmium contamination, a pot experiment with Medicago sativa, Trifolium pre-tense, and Astragalus adsurgens was conducted, with their plant height, root length, plant bio-mass, 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), re-spectively. 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. Pratease leaf, were significantly positively correlated with the application amounts of Cu~(2+) and Cd~(2+). Un-der the application of Cd~(2+), all the three leguminous plants grew normally. When the application amount of Cu~(2+) was≤1200 mg·kgM-1, T. Pratense grew normally, while the growth of M. Sativa was significantly inhibited. The growth of A. Adsurgens was inhibited when the application amount of Cu~(2+) was≥800 mg·kg~(-1). An apphcation amount of≤1200 mg·kg~(-1) of Cu~(2+) pro-moted the N, P and K absorption of M. Sativa, 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 in-creased when the application amount of Cu~(2+) was ≤400 mg·kg~(-1), but decreased significantly when the Cu~(2+) application amount was≥800 mg·kg~(-1). When the application amount of Cd~(2+)was≤20 mg·kg~(-1) , the N, P and 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. Prat-ease to Cu~(2+) and M. Sativa to Cd~(2+).