多效唑对棉花幼苗的生理效应

多效唑抑制棉花幼苗主茎、主根和侧根伸长,增加棉苗含 N 量和干物重,增强主根脱氢酶活性,提高主根和子叶过氧化物酶和吲哚乙酸氧化酶活性,降低 IAA 的有效浓度而抑制棉花幼苗的伸长。GA 能解除多效唑的抑制作用。多效唑能增加棉苗根膜脂不饱和指数和油酸含量,降低肉豆蔻酸、棕榈酸含量,减少棉茎棕榈酸、亚麻酸含量,提高油酸、亚麻酸含量;降低棉叶亚麻酸含量,增多亚油酸、油酸含量。增大根细胞膜差别透性,影响棉苗根系对离子的吸收。多效唑抑制棉根对K~+、NH_4~+阳离子吸收率,但0.1—1ppm 时,对吸收 NH_4~+有一定促进效应:增加棉根对 NO_3~-、H_2PO_4~-阴离于吸收率。不同浓度的多效唑对棉根吸收 K~+的速率符合 Michaelis—Menten 酶动力学模式。0.1—1ppm 多效唑处理后,K~+的吸收 K_m值增大,Vmax 减少,表明 K~+吸收率下降是可靠的。

THE PHYSIOLOGICAL EFFECT OF Multi-effect Triazole ON COTTON SEEDLINGS

Multi-effect Triazole(MET)inhibited the elongation of stem,taprootand lateral roots,increased the percentage of nitrogen and dry matterweight of seedlings.After MET was added to nutrient solution,the acti-vityes of dehydrogenase in taproot,of peroxidase and IAA oxidase intaproot and cotyledon increased obviously.On the contrary,GA antagonizedthe effects mentioned above.MET raised plasmalemma permeability of root cell.The contents of polar lipid of cotton seedlings treated with MET weredifferent from that of the check ones.For example,after MET was used,the contents of myristic acid and palmitic acid in root decreased while thecontents of linolenic acid and linoeic acid increased.The IUFA(index ofunsaturation of fatty acids)of the root of the treated seedlings was alsohigher than of the check ones.MET depressed K~+ and NH_4~+ uptakes of root but promoted NO_3~- andH_2PO_4~- uptakes.The analysis of kinetics of K~+ uptake indicated that,K_mof K~+ uptake in the root treated with MET was higher and V_(max) waslower than those of the check ones.MET reduced the affinity of rootfor K~+ and depressed the uptake.In the authors'opinion,this is relatedto the increase of plasmalemma permeability of root cell promoted byMET.