苗期紫花苜蓿株体对不同地区垂穗披碱草种子萌发生长的化感作用

以发芽率、苗长、根长、苗干重、根干重变化为种子萌发和幼苗生长参数,研究苗期紫花苜蓿(Medicago sativa)植株浸提液对不同地区垂穗披碱草(Elymus nutans)种子萌发生长的化感作用。结果表明:地上部浸提液对LS、DX垂穗披碱草种子发芽率具有明显的促进作用,而对GS、KMX、LKZ、LZ地区垂穗披碱草种子发芽率均表现为抑制作用,其中对GS垂穗披碱草种子发芽率的抑制作用最强,在14.5%和5.5%浓度处理时抑制率分别为57.89%、55.26%;苗长方面,浸提液5.5%浓度对垂穗披碱草苗长的抑制率顺序为:LZNQDXLSKMXQHGSLKZ,14.5%处理时抑制率顺序为:LZKMXLKZNQGSQHDXLS,其中抑制率最高的为LZ垂穗披碱草,在14.5%和5.5%浓度处理时抑制率分别为33.03%、28.97%;根长方面,5.5%处理对垂穗披碱草根长的抑制率顺序为:QHNQLZKMX、GSLKZDX、LS,14.5%处理时抑制率顺序为:GSQH、NQLZLSKMXDXLKZ,其中在高浓度下抑制率最高的为GS垂穗披碱草,抑制率为57.69%;地上部浸提液对LKZ、LZ垂穗披碱草苗干重均具有促进作用,高浓度浸提液对NQ垂穗披碱草苗干重产生促进作用(RI0),而对KMX、DX垂穗披碱草苗干重均表现为抑制作用;根干重方面,浸提液对LS、QH、GS、NQ、LKZ垂穗披碱草根干重均有明显的抑制作用,而对KMX、DX垂穗披碱草根干重产生促进作用,高浓度浸提液对LZ垂穗披碱草的根干重产生促进作用。从根浸提液的作用来看,根浸提液除对LS、DX垂穗披碱草种子发芽率和根干重、GS垂穗披碱草种子发芽率和苗干重及NQ垂穗披碱草根干重具有促进作用外(P 0.05),对其余地区垂穗披碱草的各项指标均有明显的抑制作用(RI0)。所有以上结果表明,紫花苜蓿植株浸提液对垂穗披碱草种子萌发生长的作用具有一定的浓度效应。不同地区垂穗披碱草对紫花苜蓿地上部浸提液的敏感性趋势总体为:GSQHLSKMXNQLKZLZ,最不敏感或有促进作用的是DX垂穗披碱草;对根浸提液的敏感性趋势总体为:QHNQLZKMX,根浸提液对LS、GS、LKZ、DX垂穗披碱草种子萌发生长具有促进作用。紫花苜蓿植株不同部位浸提液对垂穗披碱草种子萌发生长的化感效应顺序为:地上部根。

Allelopathic effects of alfalfa (Medicago sativa) in the seedling stage on seed germination and growth of Elymus nutans in different areas

The allelopathic effects of water extracts from alfalfa (Medicago sativa) in the seedling stage on seed germination and growth of Elymus nutans in different areas were examined in the laboratory based on seed germination rate, seedling length, root length, and dry weight of seedlings and roots. The results showed that the seed germination rate of Elymus nutans in LS (Lhasa) and DX (Damxung County) was significantly promoted by water extracts from the aboveground alfalfa, but that of those in GS (Gansu), KMX (Kangma County), LKZ (Nagarzê County), and LZ (Nyingchi County) was inhibited, and Elymus nutans in GS was the most inhibited, with suppression rates of 57.89% and 55.26% at concentrations of 14.5% and 5.5%, respectively. At the concentration of 5.5%, the seedling length of Elymus nutans in LZ was the most inhibited with the suppression rate of 33.03%, followed successively by those in NQ (Nagqu region), DX, LS, KMX, QH (Qinghai), GS, and LKZ. At the concentration of 14.5%, the seedling length of Elymus nutans in LZ was nearly the most inhibited with the suppression rate of 28.97%, followed successively by those in KMX, LKZ, NQ, GS, QH, DX, and LS. At the concentration of 5.5%, the root length of Elymus nutans in QH had the strongest inhibition, followed by those in the order of NQ > LZ > KMX, GS > LKZ > DX, LS. At the concentration of 14.5%, the root length of Elymus nutans in GS had the strongest inhibition with the suppression rate of 57.69%, followed successively by those in the order of QH, NQ > LZ > LS > KMX > DX > LKZ. The dry weight of seedlings of Elymus nutans in LKX and LZ increased by the aboveground water extracts, whereas that of those in KMX and DX decreased and the dry weight of seedlings of Elymus nutans in NQ was only increased at high concentrations (RI > 0). The dry weight of roots of Elymus nutans in LS, QH, GS, NQ, and LKZ was decreased by the aboveground water extracts, whereas that of those in KMX and DX was increased and the dry weight of roots of Elymus nutans in LZ was only increased at high concentrations. Seed germination rate, seedling length, root length, and dry weight of seedlings and roots of Elymus nutans in most areas were significantly inhibited (RI < 0) by water extracts from the root of alfalfa, except for seed germination and dry weight of roots of Elymus nutans in LS and DX. Seed germination and dry weight of seedlings of that in GS and the dry weight of roots of that in NQ were significantly promoted (P > 0.05). All the above results showed that the sensitivity of Elymus nutans in different areas to the allelopathic effects of the aboveground alfalfa in the seedling stage is in the order of GS > QH > LS > KMX > NQ > LKZ > LZ > DX from the highest to the lowest allelopathic sensitivity. The allelopathic sensitivity to the root of the alfalfa is in the order of QH > NQ > LZ > KMX > LS,from the highest to the lowest. The allelopathic sensitivity of Elymus nutans in different areas to water extracts from the aboveground alfalfa is higher than that from the root of alfalfa.