镉、铅排异大白菜品种的筛选和鉴定及安全生产调控技术

随着工农业的快速发展，土壤重金属尤其Cd和Pb污染日益严重。筛选和培育具有重金属低积累特性的农作物排异品种被认为是当前应对土壤重金属污染最为合理和有效的途径之一。本文通过盆栽试验、大田试验和砂培试验，研究了大白菜品种对Cd和Pb的吸收和积累的品种差异、对Cd、Pb胁迫的响应以及大白菜安全生产的调控技术，得出以下结论： 1) 盆栽梯度试验中，80种大白菜地上部对Cd的吸收存在显著差异(p < 0.05)。在3种Cd处理下(1.0, 2.5和5.0 mg/kg)，80种大白菜Cd含量浓度范围分别为(mg/kg) 0.22–2.46, 0.90–14.10和2.03–18.01, 其平均值分别为 0.79, 3.76 和6.79 mg/kg DW。大白菜对Cd胁迫具有较强的耐性。大田试验中，15种大白菜的富集系数和转运系数与盆栽梯度试验的结果基本一致。排异植物的筛选和鉴定标准包括：(1)该植物的地上部和根部的Cd含量都很低或者可食部位低于有关标准；(2) 富集系数(BF) < 1.0；(3) 转运系数(TF) < 1.0；(4)该植物具有较高的Cd耐性，在较高的Cd污染下能够正常生长且生物量无显著下降。采用此标准，结合盆栽梯度试验和大田试验结果，北京新3号、绿星70和丰源新3号可鉴定为Cd排异品种。秋傲和赛新5号具有排异Cd特性，但其对Cd的耐性较差。 2) 盆栽梯度试验中，在Pb投加浓度为500和1500 mg/kg处理下，30种大白菜地上部对Pb的吸收存在显著差异 (p < 0.05)，其Pb浓度的范围分别为：0.52–8.68 和1.86–16.20 mg/kg, 其平均值分别为3.01 和6.87 mg/kg DW。并且，随着Pb浓度的增加，白菜地上部Pb含量有随之增加的趋势。大白菜对Pb具有较强的耐性。低浓度的Pb处理对大白菜的生物具有一定的促进作用。结合盆栽试验和大田试验的结果，秋傲、世博秋抗和福星80可鉴定为Pb排异大白菜品种。 3) 砂培试验中，在Cd和Pb胁迫下，大白菜地上部的丙二醛(MDA)含量增加，随着Cd处理浓度的增加，超氧化物歧化酶(SOD)活性呈现先下降后上升接着下降的趋势，酸菜王的SOD活性要高于北京新3号SOD的活性。随着Pb处理浓度的增加，福星80地上部的SOD活性随之增加，而绿星大棵菜地上部的SOD活性先下降后增加。在不同梯度的Cd处理下，大白菜地上部的可溶性蛋白(SP)含量未见显著降低，甚至有所增加，而在不同梯度的Pb处理下，大白菜地上部的SP含量有所降低。 4) 施用改良剂可升高土壤的pH值和降低土壤中的有效态Cd，从而对大白菜的生长具有促进作用。施用改良剂可显著降低大白菜对Cd和Pb的吸收和累积。

With the rapid development of industry and agriculture production, heavy metal pollution in soils, especially Cd and Pb pollution, becomes increasingly severe. The screening and breeding of excluder crop cultivars with low heavy metal accumulation is believed as one of the most reasonable and effective pathways for heavy metal pollution in soils. The pot-culture experiment, field-culture experiment and sand-culture experiment were conducted to explore cultivar differenced of uptake and accumulation of Cd and Pb in Chinese cabbage (Brassica pekinensis L.) cultivars, response of Chinese cabbage to Cd and Pb toxicity, and regulating technology for safe production of Chinese cabbage. The main results were shown below: 1) In the pot-culture experiment, significant (p < 0.05) difference existed in Cd uptake in shoots of 80 Chinese cabbage cultivars. Under 3 Cd treatments (1.0, 2.5 and 5.0 mg/kg), Cd concentration (mg/kg) in shoots of 80 Chinese cabbage cultivars ranged from 0.22 to 2.46, 0.99 to 14.10 and 2.03 to 18.01, and with the mean of 0.79, 3.76 and 6.79 mg/kg DW, respectively. Chinese cabbage had high tolerance to Cd toxicity. In the field-culture experiment, the enrichment factors (EFs) and translocation factors (TFs) in 15 Chinese cabbage cultivars were basicly in accordance to those in the pot-culture experiment. The standards for the selection and identification of excluder include (1) Cd accumulations in plant shoot and root are low, or low accumulation in the edible parts of plants, lower than relative criterion; (2) BF < 1.0; (3) TF < 1.0; (4) The plant had high tolerance to Cd toxicity and can normaly grow in pollution soils without significant decreasion in biomass. Based on these standars and the results from pot-culture experiment and field-culture experiment, New Beijing 3, Lvxing 70 and Fengyuanxin 3 can be identified as excluder cultivars. Qiuao and Saixing 5 can exclude Cd uptake, while both of them had poor tolerance to Cd toxicity. 2) There are significant (p < 0.05) difference in Pb uptake among 30 Chinese cabbage cultivars under Pb treatments 500 and 1500 mg/kg in the pot-culture experiment, ranging from 0.52 to 8.68, 1.86 to 16.20 mg/kg, and with the mean of 3.01 and 6.87 mg/kg DW, respectively. Moreover, shoot Pb accumulation in Chinese cabbage increased with the increasing of Pb concentration in soil. Chinese cabbage had high tolerance to Pb toxicity. Based on the results from pot-culture experiment and field-culture experiment, Qiuao, Shiboqiukang and Fuxing 80 can be confirmed as Pb excluder cultivars. 3) In the sand-culture experiment, malondialdehyde (MDA) concentration in Chinese cabbage shoots increased under Cd and Pb toxicity, and superoxide dismutase (SOD) activity firstly decreased and then increased. SOD activity in Suancaiwang is higher than that in Newbeijing 3. SOD activity increased with the increasing of Pb concentration, while SOD activity firstly decreased and then increased. Under different Cd treatment, soluble protein (SP) content in shoots of Chinese did not decreased significantly, and even increased to some extent. However, SP in Chinese cabbage decreased under different Pb treatments when compared to control. 4) The addition of amendments can increased pH values and decreased available Cd in soils, and thus can stimulate the growth of Chinese cabbage. The addition of amendments can decreased the accumulation of Cd and Pb in Chinese cabbage.