秸秆还田对棉花生长的化感效应

The allelopathic effects of returning cotton stalk to soil on the growth of succeeding cotton

研究了秸秆不同还田量及不同腐解时间对后茬棉花抗氧化物酶活性和光合生理特性的影响。结果表明,棉花秸秆腐解产物,在一定程度上抑制了棉花种子的萌发,延长了种子出苗时间,影响棉花植株生长。随着秸秆腐解时间延长和秸秆还田数量增加,棉花单叶净光合速率、气孔导度、蒸腾速率和胞间CO2浓度降低。当加入秸秆量为10g·kg-1时,净光合速率略高于对照,随着秸秆还田量的增加,又呈现下降趋势,表现出一定"浓度效应",其中加入秸秆量为90g·kg-1时,净光合速率下降最明显,腐解30d和60d净光合速率分别比对照减少了26.8%和43.4%;随着秸秆还田量的增多和秸秆腐解时间延长,POD活性增加,SOD活性和根系活力呈现下降趋势,叶片MDA含量却升高。表明棉花秸秆还田后分解产生的化学物质具有一定的自毒效应,对连作棉花种子萌发、抗氧化物酶活性和光合生理造成影响。

A pot experiment was conducted to investigate effects of addition rates of cotton stalk and the decomposed days of cotton stalk on the antioxidant enzyme activity and physiological parameters relative to photosynthesis of cotton. Results showed that substances from decomposed contton stalk inhibited the germination of seeds and the growth of seedling for cotton to some extent. With increasing decomposed days of cotton stalk, and rate of stalk added, the net photosynthetic rate （Pn）, stomatal conductance （Gs）, Transpiration rate （Tr） and intracellular CO2 （Ci） in succeeding cotton leaves decreased respectively. When stalk addition rate was 10 g. kg^-1 , Pn value was slightly higher than control （without cotton stalk addition ）, while when stalk addition rates increased progressively, Pn value decreased correspondingly. At the addition rate of 90 g.kg^-1, Pn value of succeeding cotton leaves decreased 26.8% and 43.4% respectively at 30-day and 60-day decomposed time. With increasing stalk rate and decomposed time, POD activity increase, SOD and root vigor was declined too, but MDA content in leaf was enhanced. The results suggested that the decomposing substances after cotton stalks returned to soil have autotoxic effect. Cotton seed germination and photosynthesis physiological activities were affected by decomposed substances of cotton stalks.