看麦娘根系对小麦根水提液化感作用的生理响应

Physiological response of Alopecurus aequalis root to allelopathic effects of wheat(Triticum aestivum L.) root tissue extracts

为探讨小麦化感作用机理,以强化感小麦‘115/青海麦’、‘92L89’和弱化感小麦‘抗10103’材料,设置小麦根水提液浓度为0%、0.2%、1.0%和5.0%的水培试验,测定了看麦娘根系对小麦根水提液化感作用的生理响应。结果表明,小麦根水提液处理显著抑制了看麦娘根的生长,根鲜重抑制率随处理浓度的升高而增大,强化感小麦的抑制率高于弱化感小麦。当处理浓度达5.0%时,不同化感小麦间无显著差异。‘115/青海麦’、‘92L89’和‘抗10103’根水提液处理后,看麦娘的根系活力的抑制率分别为52.0%～59.6%、46.5%～55.0%和27.2%～44.7%,但前二者间无显著差异;看麦娘根系中可溶蛋白含量、SOD、POD、CAT活性及MDA含量显著升高;SOD和POD活性大小均表现为‘115/青海麦’〉‘92L89’≈‘抗10103’;CAT活性随处理浓度的升高显著增大,但不同品种小麦间无显著差异。‘115/青海麦’、‘92L89’和‘抗10103’根水提液处理的看麦娘根系MDA含量依次是对照的10.9～25.5倍、5.9～24.2倍和1.2～6.8倍。小麦化感作用引起看麦娘根系细胞膜脂氧化胁迫,并诱导看麦娘根系抗氧化物质类黄酮和总酚含量的合成。可见,降低根系活力、增强保护酶系统活性及抗氧化物质代谢是看麦娘应答小麦化感作用的生理响应。

In order to illustrate the mechanism of wheat allelopathy, two strong allelopathic wheat accessions（‘115/Qinghai＇ and ‘92L89＇） and one weak allelopathic accession（‘Kang10103＇） were used in a set of hydroponic culture experiments. Roots of Alopecurus aequalis were treated with 0%, 0.2%, 1.0% and 5.0%（v/v） water-based extracts of root tissues of different wheat accessions to determine physiological responses of A. aequalis root to the wheat root extracts. The results showed that extracts significantly inhibited the growth of A. aequalis, with root fresh weight decreasing with increasing extract concentration. Also strong allelopathic accessions had higher inhibitory rates than weak accession. No differences existed among the 3 accessions when extract concentration reached 5.0%. After exposure to extracts, A. aequalis root vigor declined at inhibitory rates of 52.0%-59.6%, 46.5%- 55.0% and 27.2%-44.7% respectively for ‘115/Qinghai＇, ‘92L89＇ and ‘Kang10103＇. Also no differences were noted between the two strong allelopathic accessions. The contents of soluble protein and methane dicarboxylic aldehyde（MDA） as well as the activities of superoxide dismutase（SOD）, peroxidase（POD） and catalase（CAT） of A. aequalis roots increased significantly after treated with wheat root extracts. The order of the activities of SOD and POD was ‘115/Qinghai＇ 〉‘92L89＇ ≈ ‘Kang10103＇. The activity of CAT changed significantly with changing concentrations of the extracts, and not with different wheat varieties. The contents of MDA in roots of A. aequalis treated with ‘115/Qinghai＇, ‘92L89＇ and ‘Kang10103＇ root tissues extracts were respectively 10.9-25.5 times, 5.9-24.2 times and 1.2-6.8 times that of the control. Lipid peroxidation was activated and anti-oxidative flavonoids and phenols were induced in the roots by wheat allelopathy. Thus decreasing root vigor, enhancing protective enzyme activities and synthesizing anti-oxidative substances were promising physiological responses of roots of A. aequalis exposed to wheat allelopathy.