连作对花生根系分泌物化感作用的影响

采用连续收集法提取连作5 年、3 年和轮作处理的花生结荚期根系分泌物, 研究其对土壤微生物及花生种子发芽、幼苗生长发育和细胞膜过氧化的化感作用及连作对花生根系分泌物化感作用的影响。结果表明,花生结荚期根系分泌物对花生根腐镰刀菌36194 菌丝的生长、叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及丙二醛(MDA)含量存在促进作用, 对固氮菌14046 的生长, 花生种子胚根的伸长、幼苗的苗高、茎叶鲜重、根系鲜重、叶片叶绿素含量等有抑制作用, 促进和抑制作用均随根系分泌物添加浓度和连作年限的增加呈增强趋势。连作花生结荚期根系分泌物化感物质在土壤中的累积, 很可能是导致花生连作障碍的原因之一。

Effect of continuous cropping on allelopathy of peanut root exudates

Root exudates of peanut at podding stage under 3 years and 5 years of continuous cropping, and rotation cropping were collected using the continuous collection method. Allelopathic effects of the collected root exudates on soil microbes, peanut seed germination, seedling growth and development and membrane peroxidation were analyzed. The effects of continuous cropping on allelopathic effectiveness of peanut root exudates were also investigated. Results showed that root exudates at peanut podding stage stimulated the growth of root rot fungi (Fusarium sp.) 36194 mycelium, and activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and the content of malondialdehyde (MDA) in peanut leaf. It, however, inhibited the growth of N-fixing bacteria (Bradyrhizobium vigna) 14046, the elongation of seedling radicle and height, the fresh weights of leaf and stem, and root, and leaf chlorophyll content. The stimulating and inhibitive effects of peanut root exudates increased with both the increasing concentration of exudates and the length of period of continuous cropping. Accumulation of allelopathic substances in root exudates at podding stage was a possible obstacle to continuous peanut cropping.