黄瓜对镉污染的适应性及安全性评价研究

Study on the Cucumber Adaptability and Safety Evaluation of Cadmium Pollution

摘要: 黄瓜对不同镉污染水平的响应与镉胁迫的适应性，以苗期人工添加镉的实验室研究居多，基于大田生产环境的研究甚少。本试验在0.78 mg/kg、1.46 mg/kg、2.12 mg/kg三种大田土壤镉背景下，以津优48号、蔬研白绿、津优35号等9个黄瓜品种为材料，采用随机区组设计，初步研究了黄瓜在大田生产环境下对不同镉污染水平的响应能力，以及镉污染对黄瓜生长发育及不同部位果实镉含量的影响，并对黄瓜食品的镉安全性进行了初步评价。同时，以津优35号、津优48号、蔬研白绿三个主栽品种为材料，采用对比设计方法，研究了纳米技术对黄瓜果实的降镉效果。结果表明：1) 在高镉土壤背景下，所有黄瓜果实检测样本的镉含量均低于0.05 mg/kg的国家绿色食品标准，且黄瓜生长发育正常，说明黄瓜具有很强的抗镉污染能力，属低镉吸收积累蔬菜作物，其食用果实具有很高的镉安全水平。2) 在土壤镉背景值0.78 mg/kg、1.46 mg/kg、2.12 mg/kg时，低节位黄瓜果实平均镉含量分别为0.0133 mg/kg、0.0271 mg/kg、0.0320 mg/kg，黄瓜果实镉含量随着土壤镉背景值的提高而增加，且二者间存在极显著的直线回归关系(P = 0.01)。不同黄瓜品种适应的土壤镉临界值在2.6593~4.3021 mg/kg之间，对镉适应能力排序为：津优48号 > 蔬研五号 > 蔬研翠玉 > 津优35号 > 浏阳白黄瓜 > 蔬研十号 > 蔬研白绿 > 湘园一号，生产上应根据土壤的污染程度选择不同镉适应能力的品种。3) 在土壤镉背景0.78 mg/kg时不同品种间果实镉含量差异显著(P = 0.05)，而1.46 mg/kg时不同品种间无显著差异；同时，在土壤镉背景0.78 mg/kg时不同黄瓜品种果实镉含量与1.46 mg/kg土壤镉背景下果实镉含量增加值之间存在显著的负相关关系(P = 0.05)，说明随着镉胁迫水平的提高，吸收积累镉能力较强的黄瓜品种产生了较大的镉抗拒能力或镉适应能力。4) 在土壤镉背景2.12 mg/kg条件下，津优35号、津优48号、蔬研白绿的中部节位(第7~8节位)果实镉含量较低节位(第3~4节位)黄瓜分别降低了62.95%、44.7%和41.07%，差异达极显著水平(P = 0.01)，说明黄瓜不同品种由根茎向中上部果实转运或迁移镉的能力存在明显差异，黄瓜中上部果实的镉安全水平较下部果实显著提高。5) 纳米技术(第一代降镉产品)对黄瓜具有一定的降镉作用，但降镉效果未达到显著水平(P = 0.05)。可见，黄瓜作物对镉污染土壤的适应能力较强，黄瓜果实在土壤镉含量2.12 mg/kg时仍具有很好的安全性，该研究将为重金属污染土壤的蔬菜产业结构调整、黄瓜低镉品种选育与应用提供新的思路和实践指导。

Abstract: Cucumber is one of the main vegetables in the world. Zhuzhou area accounts for about 3.2% of the vegetable cultivation area. The response of cucumber to different levels of cadmium pollution and the adaptability of cadmium stress are mostly laboratory studies of artificially adding cadmium at the seedling stage, and there is little research based on the field production environment. Under the cadmium background of 0.78 mg/kg, 1.46 mg/kg, and 2.12 mg/kg soils in this experiment, 9 cucumber varieties including Jinyou 48, Shuyan Bailv and Jinyou 35 were used as materials. Ran-domized design was used to research the ability of cucumber to different levels of cadmium pollu-tion, the effect of cadmium pollution on the growth and development and cadmium content in dif-ferent parts. The cadmium safety of cucumber food was also studied. At the same time, with the three main varieties of Jinyou 35, Jinyou 48, and Baiye of green vegetables as materials, compara-tive design methods were used to study the effect of nanotechnology on the cadmium-reducing ef-fect of cucumber fruits. At the same time, with the three main varieties of Jinyou 35, Jinyou 48, and Baiye of green vegetables as materials, the comparative design method was used to study the effect of nanotechnology on the cadmium reduction of cucumber fruits for the first time. The results showed that: 1) In the high cadmium soil background, the cadmium content of all cucumber fruit samples was lower than the national green food standard of 0.05 mg/kg, and the cucumber was normal in growth and development, indicating that cucumber has strong cadmium-resistance ability, and is a low-cadmium absorption of accumulated vegetable crops; its edible fruit has a high level of cadmium safety. 2) In the soil cadmium background values of 0.78 mg/kg, 1.46 mg/kg, 2.12 mg/kg, the average cadmium content of low-node cucumber fruits was 0.0133 mg/kg, 0.0271 mg/kg, and 0.0320 mg/kg, respectively. The content of cadmium in fruits increased with the in-crease of soil cadmium background value, and there was a very significant linear regression relationship between them (P = 0.01). The critical value of soil cadmium in different cucumber varieties was between 2.6593 - 4.3021 mg/kg, and the order of cadmium adaptability was: Jinyou 48 > Vegetable Research V > Vegetable Research Cuiyu > Jinyou 35 > Liuyang White Cucumber > Vegetable Research No. 10 > Vegetable Research Bailv > Xiangyuan No. 1; production should be based on the degree of contamination of the soil to select different varieties of cadmium adaptability. 3) Cadmium content in different cultivars was significantly different (0.77 mg/kg) (P = 0.05), but there was no significant difference among different cultivars at 1.46 mg/kg. At the same time, the soil cadmium background was 0.78 mg/kg. There was a significant negative correlation between the cadmium content in fruits of different cucumber cultivars and the increase of cadmium content in the cadmium background of 1.46 mg/kg soil (P = 0.05), indicating that the cadmium stress level in-creased with the increase of cadmium stress. Cucumber varieties that have a higher ability to accumulate cadmium have a greater cadmium resistance or cadmium adaptability. 4) Under the condition of soil cadmium background 2.12 mg/kg, the lower cadmium content in the fruits (7 - 8th position) in the middle position of Jinyou 35, Jinyou 48, and Baiyan of vegetable research (Section 3 - 4) cucumber decreased by 62.95%, 44.7% and 41.07% respectively, and the difference was extremely significant (P = 0.01). This indicated that the ability of different varieties of cucumber to transfer or migrate cadmium from the rhizomes to the middle and upper parts of cucumbers was significantly different. The level of cadmium in the upper middle fruits was significantly higher than that in the lower part. 5) Nanotechnology (the first generation of cadmium reduction products) had a certain cadmium-reducing effect on cucumbers, but the cadmium reduction effect did not reach a significant level (P = 0.05). It can be seen that cucumber crops have strong adaptability to cadmium-contaminated soils. Cucumber fruits still have good safety when the soil cadmium content is 2.12 mg/kg. This study will adjust the structure of vegetable industry in heavy metal-contaminated soils and low cadmium varieties of cucumbers. Breeding and application provide new ideas and practical guidance.