砷脅迫對魚腥草生長發育、光合特征及砷積累的影響

摘 要：為了探明砷脅迫對魚腥草生長發育、光合特征及砷積累的影響，采用盆栽試驗研究了不同濃度砷脅迫（0、40、80和120 mg/kg）處理下魚腥草的生長狀況（生長發育指標、光合特征）和不同部位（地下莖、地上莖、葉）的砷含量。結果表明：當砷脅迫濃度超過40 mg/kg時，對魚腥草的生長發育有顯著的抑制作用且顯著降低了葉片凈光合速率（Pn）、蒸騰速率（Tr）和氣孔導度（Gs），同時顯著增加了胞間CO2濃度（Ci）；砷脅迫濃度與魚腥草生長發育各指標均呈現不同顯著水平的負相關，與光合特性中的Pn、Tr和Gs均呈極顯著負相關，而與 Ci呈極顯著正相關；魚腥草不同部位的砷含量隨砷脅迫濃度的而增高，表現出葉＞地上莖＞地下莖的分布。因此，為保證魚腥草的生長發育和產量，應控制魚腥草生長區土壤砷濃度在40 mg/kg以下。

關鍵詞：魚腥草；砷脅迫；生長發育；光合特性

中圖分類號：X53 文獻標識碼：A 文章編號：1006-060X（2023）07-0034-06

Abstract：The main objective of this experiment is to study the effects of As stress on the growth， photosynthetic characteristics and As accumulation of Houttuynia cordata. The growth status of H. cordata （morphological indices and photosynthetic characteristics） and the content of As in each part of the plants （underground stem， overground stem and leaf） under different levels of As stress （0， 40， 80 and 120 mg/kg） were investigated through a pot culture method. The results showed that when the concentration of As was ≥ 40 mg/kg， the plant growth and development was inhibited markedly， the net photosynthetic rate of leaves （Pn）， transpiration rate （Tr） and stomatal conductance （Gs） were reduced significantly， but the intercellular CO2 concentration （Ci） was dramatically increased. We found that As concentration was negatively correlated with the growth and development indicators of H. cordata at different significant levels， was very significantly negatively correlated with Pn， Tr and Gs， and was very significantly positively correlated with Ci. The content of As in different parts of H. cordata increased with the increase of As stress level， presenting a gradient distribution of leavesgt;overground stemgt;underground stem. Therefore， to ensure the growth and yield of H. cordata， the As concentration in the soil of the growing area should be controlled below 40 mg/kg.

Key words： Houttuynia cordata; As stress; growth and development; photosynthetic characteristics

砷（As）廣泛存在于自然界中，對植物有劇毒，被美國毒物和疾病登記署列為最嚴重的10種有毒物之首。當少量砷進入人體被吸收后，可以破壞細胞的氧化還原能力，影響細胞正常代謝，引起組織損害和機體障礙，最終引起中毒死亡；而大量砷化物進入體后可以麻痹中樞神經，使人體出現四肢疼痛性痙攣、意識模糊、譫妄、昏迷、脈搏速弱、血壓下降、呼吸困難等癥狀，數小時內就會致人死亡[1-2]。伴隨著采礦、冶金以及工農業的發展，大量砷元素進入到農田生態系統中，導致耕地污染日益嚴重。據調查，湖南、云南、廣西、廣東等省的土壤中砷含量達到16.4～19.20 mg/kg，均值為17.8 mg/kg[3]。……