模拟酸雨及其酸化土壤对小麦幼苗生物量和某些生理活动的影响

Effect of Simulated Acid Rain and Its Acidified Soil on the Biomass and Some Physiological Activities of Wheat Seedlings

以小麦为试材,采用盆栽的方法研究了模拟酸雨及其酸化土壤对小麦幼苗生物量和某些生理活动的影响。结果表明,pH值为5.6、4.5、3.5、3.0和2.5的系列模拟酸雨对黄棕壤的淋溶,引起了土壤酸化和盐基流失。当模拟酸雨的pH值由5.6下降到2.5时,被淋溶土壤的pH值也由6.06下降到3.41,且交换性盐基总量从56.5mmol.kg-1下降到41.1mmol.kg-1。将小麦幼苗栽培在该系列酸化土壤中,并分别用5种不同pH值的模拟酸雨喷淋地上器官,导致小麦幼苗的生物量迅速下降和某些生理活动降低。其中模拟酸雨喷淋小麦幼苗对株高、地上部干重、叶绿素含量以及光合速率的影响大于酸化土壤对其产生的影响。而酸化土壤对小麦幼苗的单株次生根条数、根干重、根系活力以及根系呼吸速率的影响大于模拟酸雨喷淋对其产生的影响。pH≤3.0的高强度酸雨以及由其产生的酸化土壤(T4、T5土壤)对小麦幼苗的生长发育、生理活动产生了明显的伤害作用。

Acid rain can damage either plant leaves directly or plant roots indirectly resulting from soil acidification and release of base ions. The stress effect of acid rain and its acidified soil does a lot of harm to the plants. A pot experiment of wheat seedlings was conducted to study the effects of simulated acid rain and its acidified soil on the biomass and physiological activities. The results showed that leaching lose of base ions was caused by simulated acid rain treatments with pH 5.6, 4.5, 3.5, 3.0 and 2.5. With the decrease of pH value of simulated acid rain from 5.6 to 2.5, the pH value of the acid rain-leached-soil decreased from 6.06 to 3.41 and the total amount of exchange able base ions decreased from 56.5 mmol· kg^-1 to 41.1 mmol· kg^-1. Spraying the shoots of the wheat seedlings planted in such acidified soils by simulated acid rain with five different pH values caused a rapid decrease in the biomass and some physiological activities. Plant height, shoot dry weight, chlorophyll content and photosynthetic rate of wheat seedlings were greater when the plant was treated by simulated acid rain than by acidified soil, while secondary root number per plant, root dry weight, root activity and root respiratory rate were greater when the plant was treated by acidified soil than by simulated acid rain. The obvious harm to the growth and physiological activity of wheat seedlings was caused by the simulated acid rain and acidified soil both with pH≤3.0.