红薯叶片浸提液对5种主要农田杂草种子萌发及幼苗生长的化感作用

以发芽率、发芽势、根长、茎长和鲜重变化为种子萌发和幼苗生长参数,研究了作物红薯叶片水浸液对云南省农田5种恶性杂草牛膝菊、藿香蓟、鬼针草、马唐和稗草的化感作用。结果表明,红薯叶片水浸液对5种受体杂草种子发芽率的影响不明显,但对发芽势有显著抑制作用。牛膝菊、藿香蓟、鬼针草和马唐的根长和生物量随红薯叶片水浸液浓度增加而显著降低,其中对马唐的抑制最强,高浓度0.1 g/m L时对根长和生物量抑制率分别为92.04%和73.33%,而低浓度0.0125 g/m L时分别为40.99%和46.67%;其次为鬼针草、藿香蓟、牛膝菊;最差的是稗草,随浓度的变化趋势均不明显。随红薯叶片水浸液浓度增加牛膝菊、鬼针草和马唐的茎长显著地降低,其中对马唐的抑制最强,高浓度0.1 g/m L和低浓度0.0125 g/m L时分别为86.85%和70.64%;其次为鬼针草和牛膝菊;相反藿香蓟和稗草的茎长随浓度增加而显著增加,高浓度0.1 g/m L和低浓度0.0125 g/m L时对藿香蓟的促进率分别为86.97%和16.03%。红薯叶片水浸液低浓度0.0125 g/m L时对牛膝菊的茎长和生物量有促进作用(低促高抑)。从化感作用响应指数和综合效应指数的综合对比来看,红薯对牛膝菊、藿香蓟、鬼针草、马唐具有显著的化感抑制作用,随浓度增加其抑制能力显著增加;其中对马唐的为最强,其次为鬼针草、牛膝菊和藿香蓟,相反对稗草具有促进作用(除了浓度0.1 g/m L)。所有这些表明,红薯叶片水浸液对5种杂草化感作用的敏感性趋势总体为:马唐鬼针草牛膝菊藿香蓟,最不敏感或者具有促进作用的是稗草。

Allelopathic effects of water extracts from sweet potato (Ipomoea batatas) leaves on five major farming weeds

The allelopathic effects of water extracts from sweet potato (Ipomoea batatas) leaves on seed germination and seedling growth of five noxious farming weeds (Galinsoga parviflora, Ageratum conyzoides, Bidens pilosa, Digitaria sanguinalis, and Echinochloa crusgalli) in the Yunnan Province, China were examined in the laboratory. Effects were based on seed germination rate, seed germination vigor, root length, stem length, and fresh biomass. The results showed that the seed germination vigor of the five weeds was markedly suppressed by water extracts of sweet potato leaf, but seed germination rates were less influenced. Root length and fresh biomass of G. parviflora, A. conyzoides, B. pilosa, and D. sanguinalis were significantly reduced with increasing concentration of water extracts of sweet potato leaf, and D. sanguinalis was the most inhibited, with suppression rates of 92.04% (length) and 73.33% (biomass) at a concentration of 0.1 g/mL, 40.99% (length) and 46.67% (biomass) at a concentration of 0.0125 g/mL. The next most suppressed species were B. pilosa, A. conyzoides and G. parviflora; and the least suppressed was E. crusgalli. With increasing concentration of water extracts of sweet potato leaf, stem length of G. parviflora, B. pilosa and D. sanguinalis was significantly decreased. The highest inhibition was for D. sanguinalis, consisting of 86.85% and 70.64% at concentrations of 0.1 g/mL and 0.0125 g/mL, respectively, followed by B. pilosa and G. parviflora. However, the stem length of A. conyzoides and E. crusgalli was significantly increased with concentration increases in water extracts of sweet potato leaf, and for A. conyzoides rates of promotion were 86.97% and 16.03% at concentrations 0.1 g/mL and 0.0125 g/mL, respectively. For stem length and biomass of G. parviflora, the water extracts of sweet potato leaf showed a "low-promotion and high-inhibition effect" at a concentration of 0.0125 g/mL water extracts of sweet potato leaf. Generally, compared to combination of response index and synthetical allelopathic index, G. parviflora, A. conyzoides, B. pilosa, and D. sanguinalis were significantly inhibited with increasing concentration of water extracts of sweet potato leaf, and D. sanguinalis had the strongest inhibition, followed by B. pilosa, G. parviflora and A. conyzoides, however E. crusgalli exhibited positive effects (except at a 0.1 g/mLconcentration). Thus the sensitivity of five weeds to the allelopathic effects of sweet potato is in the order of D. sanguinalis > B. pilosa > G. parviflora > A. conyzoides > E. crusgalli from highest to lowest allelopathic sensitivity.