模拟岩溶旱钙土壤基质中AM真菌对玉米幼苗光合生长的影响

利用盆栽试验,探讨了AM真菌在模拟岩溶区干旱、高钙及其双重胁迫的土壤基质中对玉米幼苗光合生长的影响。结果表明:玉米幼苗的菌根侵染率在不同处理下的大小顺序为对照干旱双重胁迫高钙。无论接种与否,干旱、高钙及其双重胁迫均导致玉米幼苗生物量、净光合速率下降。未接种AM真菌条件下,玉米幼苗生物量在干旱、高钙及其双重胁迫下较对照分别低3.2%、63.7%、76.0%,净光合速率较对照分别低33.4%、86.9%、98.8%;接种AM真菌条件下,玉米幼苗生物量在干旱、高钙及其双重胁迫下较对照分别低16.3%、78.4%、80.2%,净光合速率较对照分别低9.7%、92.8%、91.7%。与同种条件下的非菌根植株相比,干旱及双重胁迫下的菌根植株生物量、叶绿素含量、光合蒸腾速率、最大光化学效率,以及P吸收均呈上升趋势;高钙胁迫下的菌根植株叶绿素含量、最大光化学效率有所增加,但生物量、光合蒸腾速率以及N、P的吸收未体现菌根促进效应。AM真菌与干旱及双重胁迫的交互作用对玉米幼苗的净光合速率影响显著,与高钙交互作用对玉米幼苗净光合速率无显著影响。AM真菌能够通过促进玉米幼苗N、P吸收及叶绿素含量增加,光化学效率、气孔导度增大,从而提高玉米幼苗光合作用能力促进生长。实验结果对岩溶生态系统中合理利用菌根技术及制定合理的农业生产措施具有重要的理论和实践意义。

Effect of AMF on the photosynthetic characteristics and growth of maize seedlings under the stress of drought, high calcium and their combination in Karst area

Drought and high concentration of calcium are the main characters of the karst soils, and always show great heterogeneity in the karst ecosystems. In order to explore the effects of AMF on the photosynthetic and growth characters of maize (Zea mays L.) under various stresses, three treatments including drought, high concentration of calcium (high Ca), and their combination (double stress) were applied to potted maize seedlings. The results showed that the colonization rate of the AMF to maize seedlings was following the sequence of: control > drought > double stress > high Ca. Compared to the control group, the biomass, net photosynthetic rate (Pn) of the seedlings were decreased in the three treatments. Under non-inoculation conditions, the biomass of maize seedlings subjected to drought, high calcium and double stress were 3.2%, 63.7%, 76% lower than that of control respectively, while those of Pn were 33.4%, 86.9%, and 98.8%. In the same time, under inoculation conditions, compared with the control, the seedling''s biomass in drought, high calcium and double stress were 16.3%, 78.4%, 80.2% lower, and net photosynthetic rate were 9.7%, 92.8%, and 91.7% lower. Additionally, compared to the seedlings without AMF, those vaccinated AMF showed significantly higher biomass, chlorophyll content, transpiration rate (Tr), maximum photochemical efficiency, and absorbed more phosphorus, when subjected to the drought and double stress. On the contrary, in the environment of high calcium, the AMF only enhanced the content of chlorophyll, maximum photochemical efficiency, while there was no increase in terms of plant biomass, Tr and the absorbing amount of nitrogen and phosphorus. Moreover, the interaction of AMF×drought and AMF×double stress had significant effects on the Pn of seedlings, while no significant effects of AMF×high Ca were found on the Pn. AM fungi can assist the plant to absorb more phosphorus, enhancing the contents of chlorophyll, improving the activity of light reaction center, increasing the plant stomatal conductance, so as to enhance photosynthesis ability to promote the growth of plant. This research can provide references for a reasonable utilization of AMF and increasing agricultural productivity in the karst ecosystem.