乌头块根浸提液对3种牧草的化感效应

Allelopathic effects of extracts from tuberous roots of Aconitum carmichaeli on three pasture grasses

乌头Aconitum carmichaeli是传统的大宗中药材之一,广泛种植于四川省江油市,所释放的化感物质严重影响周围和后茬作物的生长发育。试验以当地种植乌头的后茬牧草白三叶、黑麦草和紫花苜蓿为材料,研究了乌头块根浸提液(ETR)浸种对种子萌发和幼苗生长的化感效应。结果表明,牧草品种不同,种子发芽和幼苗生长对ETR浓度的响应也不一样。低浓度的ETR(0.01 g·L-1)促进紫花苜蓿种子发芽,ETR 1.00 g·L-1对3种牧草的种子发芽率均有抑制作用。用高浓度的ETR(1.00 g·L-1)浸种,苗高的最大降幅为:紫花苜蓿(42.05%)≥白三叶(40.21%)>黑麦草(10.64%)。因此,在乌头-牧草种植体系中,选择对ETR相对不敏感的黑麦草有益于减轻乌头产生的化感效应,提高土地整体生产力。随ETR浸种浓度提高,抑制牧草种子中的蛋白质、淀粉和肌醇磷酸盐水解,降低游离氨基酸、可溶性糖和可溶性磷含量,进而影响种子发芽。此外,高浓度的ETR还显著降低牧草幼苗的根系活力、硝酸还原酶活性和叶绿素含量,说明ETR中的化感成分可抑制养分吸收,硝酸盐同化和光合作用,妨碍幼苗生长。

The tuberous roots of Aconitum carmichaeli are largely used in traditional Chinese medicine and widely grown in Jiangyou,Sichuan,China. During the growth process,this medicinal plant releases a large amount of allelochemicals into soil,which retard the growth and development of near and late crops. Therefore,a pure culture experiment was thus carried out by seed soaking to study the allelopathic effects of extracts from tuberous roots of A. carmichaeli（ ETR） on the seed germination and young seedling growth of Lolium perenne,Trifolium repens,and Medicago sativa,the late pasture grasses after cultivation of A. carmichaeli. The results showed that three pasture grasses varied significantly in seed germination and young seedling growth in response to ETR concentrations. Seed germination of M. sativa was stimulated by low ERT concentration（ 0. 01 g·L- 1）,while all of pasture grass seeds germinated poorly in solution with 1. 00 g·L- 1. Seed soaking with 1. 00 g·L- 1also inhibited significantly the growth of pasture young seedlings,with M. sativa showing the highest seedling height reduction of 42. 05% in seeding height,followed by T. repens（ 40. 21%） and L. perenne with about 11%. Cultivation of L. perenne could thus be beneficial to increase whole land productivity in A. carmichaeli-pasture grass cropping systems. In addition,hydrolysis of protein,starch,and inositol phosphates was blocked and free amino acids,soluble sugars and phosphorus were decreased in seeds by seed soaking with ETR,which could be one of the reason for the inhibition of seed germination. There was a significant reduction in root vigor,nitrate reductase,and chlorophyll after the seed treatment with ETR,indicating the suppression of nutrient uptake,nitrate assimilation,and photosynthesis by allelopathic chemicals in ETR,which could lead to the slow growth rate of pasture grass seedlings.