Abstract:

The effects of heavy metals: copper, cadmium and lead on the seed germination and seedling growth of seven kinds of leguminous forage were studied in this paper with the distilled water as control. The results showed that with the increases of Cu²⁺, Cd²⁺ and Pb²⁺ concentrations, the seed germination percentage, germination index, seedling root length and shoot length of Vicia villosa, Trifolium pratense, Medicago varia, Coronilla varia, Medicago ruthenica, and Lotus corniculatus decreased. The seed germination percentage of Vicia villosa under 300 mg·L^-1 Cu²⁺ concentration was significantly higher than that of control (P <0.05). The germination indexes of Onobrychis viciaefolia seeds under 200, 300 and 400 mg·L^-1 Cu²⁺ concentrations were significantly higher than that of control (P <0.05). The germination index of Onobrychis viciaefolia seed under 150 mg·L^-1 Cd²⁺ concentration was significantly higher than that of control (P <0.05). The germination indexes of Onobrychis viciaefolia seeds under 500 or 1000 mg·L^-1 Cd²⁺ concentrations were significantly higher than that of control and the treatment of 2000 mg·L^-1 Pb²⁺ concentration (P <0.05). The shoot and root lengths of Onobrychis viciaefolia seedling showed a decreasing tendency with the increases of Cu²⁺, Cd²⁺ and Pb²⁺ concentrations. The comprehensive evaluations of the resistance of leguminous plant seeds to the metal ions during germination stage were done by membership function method. The resistance of seed to Cu²⁺ stress was ordered as Onobrychis viciaefolia >Vicia villosa >Trifolium pratense >Lotus corniculatus >Medicago varia >Medicago ruthenica >Coronilla varia, and to Cd²⁺ stress was ordered as Onobrychis viciaefolia >Vicia villosa >Trifolium pretense>Lotus corniculatus >Medicago ruthenica >Medicago varia>Coronilla varia, while to Pb²⁺ stress was ordered as Onobrychis viciaefolia >Vicia villosa >Medicago ruthenica >Trifolium pratense >Coronilla varia >Medicago varia>Lotus corniculatus. Comprehensive analyses showed that the resistances of the Onobrychis viciaefolia and Vicia villosa seeds to heavy metals of Cu²⁺, Cd²⁺ and Pb²⁺ during seed germination period were better than other five tested plants.

Key words: Leguminous forage, Seed germination, Seedling growth, Cu²⁺, Cd²⁺, Pb²⁺

摘要：

以蒸馏水为对照,研究了重金属铜、镉、铅离子对7种豆科植物种子萌发和幼苗生长的影响。结果表明,随着Cu²⁺,Cd²⁺和Pb²⁺浓度的增大,毛苕子(Vicia villosa)、红三叶(Trifolium pratense)、苜蓿(Medicago varia)、小冠花(Coronilla varia)、扁蓿豆(Medicago ruthenica)和百脉根(Lotus corniculatus)种子的发芽率、发芽指数、幼苗的根长和芽长均呈不同程度的降低趋势;但毛苕子的降低趋势相对较缓。经300 mg·L^-1的Cu²⁺处理后,红豆草种子发芽率显著高于对照(P <0.05),在200,300和400 mg·L^-1浓度的Cu²⁺下红豆草种子的发芽指数均显著高于对照;经150 mg·L^-1的Cd²⁺浓度处理下红豆草种子的发芽指数显著高于对照;在500和1000 mg·L^-1 的Pb²⁺处理下红豆草种子的发芽指数显著高于对照和2000 mg·L^-1 的Pb²⁺处理(P <0.05)。随着Cu²⁺,Cd²⁺和Pb²⁺离子浓度的增大,红豆草种子萌发后形成的幼苗的根长和芽长都呈降低趋势。采用模糊数学隶属函数法,对供试7种豆科植物种子相对发芽率、相对发芽指数、相对芽长和相对根长进行隶属函数值计算,得出种子萌发期耐重金属胁迫的隶属函数总平均值,耐Cu²⁺的强弱顺序为:红豆草 >毛苕子 >红三叶 >百脉根 >苜蓿 >扁蓿豆 >小冠花;耐Cd²⁺的强弱顺序为:红豆草 >毛苕子 >红三叶 >百脉根 >扁蓿豆 >苜蓿 >小冠花;耐Pb²⁺的强弱顺序为:红豆草 >毛苕子 >扁蓿豆 >红三叶 >小冠花 >苜蓿 >百脉根。综合分析,红豆草和毛苕子种子在萌发期对重金属Cu²⁺,Cd²⁺和Pb²⁺的耐性较好。

关键词: 豆科牧草, 种子萌发, 幼苗生长, Cu²⁺, Cd²⁺, Pb²⁺