花生根系分泌物自毒作用研究

Autotoxic potential of peanut (Arachis hypogaea) root exudates

采用连续收集法提取花生植株的根系分泌物,就其对花生种子发芽、幼苗生长、细胞膜的过氧化、抗氧化酶系统的影响等进行了研究,旨在探讨花生是否存在自毒作用。结果表明,花生根系分泌物的中性、酸性和碱性组分显著抑制了胚根的生长(P<0.01),随添加浓度的增加抑制作用逐渐增强,其中,中性组分的抑制作用最强。经过20d的处理,3种组分对花生幼苗的生长均表现出显著的化感抑制作用(P<0.05),作用规律与对胚根的抑制作用相似,在中性组分最高添加浓度30 mg/L处理下,株高、地上部鲜重、根系鲜重分别为对照的80%、73%和66%。叶片中SOD和POD的活性显著提高(P<0.01),MDA的含量也显著增加(P<0.001)。3种组分中中性组分的化感促进作用最强,其次是酸性组分,碱性组分的作用相对最弱。研究结果证明了花生根系分泌物自毒作用的存在,是导致花生连作障碍的原因之一。

In this study,we assessed the autotoxic potential of peanut（Arachis hypogaea） root exudates.The effects of peanut root exudates collected using the continuous trapping system on seed germination,seedling growth,membrane peroxidation,and antioxidant enzyme activities in peanut were evaluated.Results showed that radicle elongation was significantly inhibited in a dose-dependent manner by the neutral,acidic,and basic fractions of root exudates（P0.01）.The neutral fraction showed the strongest inhibitory effect.After 20 days of treatment,all three fractions inhibited seedling growth in a similar manner to their inhibitory effects on radicle elongation（P0.05）.At a concentration of 30mg/L,the neutral fraction reduced plant height,shoot fresh weight,and root fresh weight to 80%,73%,and 66% of control values,respectively.Superoxide dismutase（SOD） activity,Peroxidase（POD） activity（P0.01） and malondialdehyde（MDA） content（P0.001） in the leaf significantly increased when peanut seedlings were treated with root exudates.Among these three fractions,the neutral fraction caused the greatest increases in antioxidant activities and MDA content,followed by the acidic fraction and the basic fraction.The results of this study demonstrated the autotoxic potential of peanut root exudates,which is one of the reasons causing continuous cropping obstacle of peanut.