3种质地土壤上As胁迫对小麦灌浆期旗叶光合特性的影响

摘要

为了深入探讨壤土、黏土、沙土3种主要农田土壤质地条件下As胁迫对小麦的影响差异,研究了小麦灌浆期的根长、分蘖、分生根数目、干物质量等形态指标及旗叶的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(Tr)、水分利用率(WUE)、叶绿素含量等光合特性指标.结果表明:当As≤15mg/kg时,小麦受到的胁迫作用不明显；当As≥30mg/kg时,小麦则开始呈现出根长降低,分生根数目减少等明显的胁迫效应.当As≥30mg/kg时,在壤土和黏土条件下生长的小麦根长较长,分生根数目较多,并且小麦旗叶的Pn、Gs、Ci、WUE、叶绿素相对含量较沙土条件下高.As胁迫对3种质地土壤上小麦植株干物质量影响不同,壤土上As≥30mg/kg时、黏土上则As≥45mg/kg时及沙土上各处理As胁迫下,小麦干物质量出现明显降低.总的来说,壤土和黏土条件可以在一定程度上缓解小麦所受到的As胁迫作用,而沙土对As胁迫缓解效果较差.因此,选择适宜的土壤质地种植小麦,能有效缓解As对小麦植株的胁迫作用.%With the same arsenic stress, there are lots of differences to wheat in different textures of soil. The influences of arsenic stress on wheat during filling stage in three textures of soil including loamy soil, clay soil and sandy soil were studied in these experiments. Many indexes of growth and photosynthesis of wheat were measured such as length and number of root, tillering, biomass, net photosynthesis rate( Pn) ,stomatic conductance ( Gs) , intercellular C02 concentration( Ci) ,transpiration rate(Tr) and content of chlorophyll of flag leaves of wheat; as well as water unitilization efficiency ( WUE ) was counted. The results showed that as the concentration of arsenic was less than 15 mg/kg,the stress to wheat was not so strong;but as the concentration of arsenic was more than 30 mg/kg, the stress of arsenic was becoming obviously, with root length and lateral root number of wheat decreasing. To different textures of soil, as arsenic 3 ≥ 30 mg/kg, root length was longer, lateral root number was more , and net photosynthesis rate, stomatic conductance , intercellular CO2 concentration, water unitilization efficiency, chlorophyll relative content of wheat flag leaves in loamy and clay soil were all higher than those in sandy soil. Additionally, biomass of different organs of wheat were all decreased as arsenic ≥30 mg/kg in loamy soil,or arsenic ≥45 mg/kg in clay soil, or all concentrations of arsenic treatment in clay soil. In short,in three textures of soil,effects of alleviating the toxic-ity of arsenic to wheat in loamy and clay soil were more obvious than that in sandy soil. So,soil texture is very important to wheat plant with arsenic stress.