不同品种蓖麻对镉的响应及修复能力评价

Evaluation of Cadmium Tolerance and Cadmium-phytoextraction Ability of 30 Castor Bean Cultivars

蓖麻(Ricinus communis L.)是一种有价值的能源作物,可用于修复镉污染农田同时生产生物能源。本研究在温室条件下(5~32℃)采用盆栽试验,设定2个镉质量分数梯度(2和5 mg·kg^(-1)),对比研究镉胁迫下30个蓖麻品种的生长状况,评估蓖麻对镉的耐性及蓖麻茎、叶和果实中镉的富集特征,以及不同蓖麻品种对镉的修复能力。研究发现,随着土壤中镉质量分数增加,10个蓖麻品种的生物量增加,20个蓖麻品种的生物量减少;表明不同品种蓖麻对镉的耐受程度不同。2 mg·kg^(-1)镉胁迫下,茎、叶和果实中镉质量分数变化范围分别为0.600~1.670、0.310~1.970和0.130~0.909 mg·kg^(-1),平均值分别为1.030、0.831和0.362 mg·kg^(-1)。5 mg·kg^(-1)镉胁迫下,茎、叶和果实中镉质量分数变化范围分别为1.012~4.032、0.698~3.514和0.227~1.525mg·kg^(-1),平均值分别为1.964、1.583和0.694 mg·kg^(-1)。蓖麻地上部分对镉的富集能力大小依次为茎、叶、果实。基于蓖麻品种茎、叶和果实中镉的质量分数,采用聚类分析的方法分析发现,30个蓖麻品种对镉的富集能力存在差异:4个蓖麻品种为高镉富集型,25个蓖麻品种为低镉富集型。根据蓖麻地上部分中镉质量分数及富集系数(小于1),判断蓖麻不是镉的超富集植物。2 mg·kg^(-1)镉胁迫下,蓖麻地上部分吸收的镉含量变化范围为26.3~65.7μg·pot^(-1),平均值为42.4μg·pot^(-1)。5 mg·kg^(-1)镉胁迫下,蓖麻地上部分吸收的镉含量变化范围为37.0~121.6μg·pot^(-1),平均值为76.0μg·pot^(-1)。蓖麻地上部分对镉的富集能力及提取能力主要由品种决定,受土壤中镉浓度的影响相对较小。因此,蓖麻作为一种潜在的镉的植物修复作物,不适用于植物提取的用途,可用于植物固定的用途;选用对镉具有较高耐性蓖麻品种种植可以在健康合理地利用镉污染农田的同时生产生物能源。

Castor bean (Ricinus communis L.), a valuable renewable resource, is cultivated as a resource for bioenergy production, and also for bioremediation. In this study, we compare the growth of 30 castor bean cultivars under 2 mg·kg-1 Cd and 5 mg·kg-1 Cd conditions in a pot experiment in the greenhouse (5~32℃). We evaluate Cd accumulation in different parts of the plants, and compare the abilities of the cultivars to extract Cd from the soil. The 30 cultivars show different degrees of Cd tolerance, as indicated by the aboveground biomass response to Cd stress index (> 0 with 10 cultivars, < 0 with 20 cultivars). Under 2 mg·kg-1 Cd conditions, the range of Cd concentrations is 0.600~1.670 mg·kg-1 in the stems, 0.310~1.970 mg·kg-1 in the leaves and 0.130~0.909 mg·kg-1 in the fruit. The average Cd concentrations in stems, leaves and fruit is 1.030, 0.831 and 0.362 mg·kg-1, respectively. Under 5 mg·kg-1 Cd conditions, the range of Cd concentrations is 1.012~4.032 mg·kg-1 in the stems, 0.698~3.514 mg·kg-1 in the leaves and 0.227~1.525 mg·kg-1 in the fruit. The average Cd concentrations in stems, leaves and fruit is 1.964, 1.583 and 0.694 mg·kg-1, respectively. Four cultivars are high-Cd accumulators, and 25 cultivars are low-Cd accumulators. The cultivars also show a range of abilities to extract Cd from soil (26.3~65.7μg·pot-1 under 2 mg·kg-1 Cd and 37.0~121.6μg·pot-1 under 5 mg·kg-1 Cd). Cd concentrations and extraction capability (EA) in aboveground organs are cultivar-dependent, and less affected by the Cd concentration in the soil. On the basis of the Cd concentrations and enrichment factors of the aerial part, castor is not a Cd hyperaccumulator. Therefore, the relative high tolerance cultivars of castor can address the Cd contaminated farmland for phytostabilization and high seed-oil production with a healthy pattern.