Abstract: Studies were conducted with five alfalfa(Medicago sativa) seed with diverse hardness levels after accelerated aging at 24~96 h.This study compares seed germination;physiological and biochemical characteristics,and determines internal physiological factors inducing seed hardness affects to seed quality.Results show that both seed germination rate and electronical conductivity increase after aging treatment.Cell membrane permeability is increased with accelerated aging,while the hardness of seed is broken.For MS-1 sample(highest hardness),germination rate,superoxide dismutase(SOD),catalase(CAT) and Malonaldehyde(MDA) decrease with aging,whereas electronical conductivity increases.After aging 72h,germination rate,electronical conductivity,CAT and SOD contents decrease,whereas MDA contents increase.For MS-4 sample(less hardness),both electronical conductivity and MDA contents increase,whereas CAT and SOD levels decrease after 48h of accelerated aging.Harder seeds have stronger resistances,but higher seed germination rate does not mean higher seed vigor.

Key words: Alfalfa, Hard seed, Accelerated aging

摘要： 以5份具有不同硬实程度的苜蓿(Medicago sativa)种子为材料,研究加速老化24~96 h对其种子发芽及生理生化特性的影响,以确定引起苜蓿种子硬实变化的内在生理因素。结果表明:经过老化处理的种子发芽率、电导率较处理之前均有所提高,人工加速老化处理可以增加细胞膜的渗透性,部分解除硬实。在具有最高硬实率的种子样品MS-1中,随着老化程度的加剧,种子发芽率、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性及丙二醛(MDA)含量均呈下降趋势,而电导率上升;在老化72 h之后发芽率、电导率、SOD、CAT活性下降,MDA则进一步积累。在硬实率最低的种子样品MS-4中,老化48 h后的电导率、MDA含量上升,CAT、SOD的活性下降。样品MS-2,MS-3,MS-5中各项生理指标没有一致性的变化规律。因此,种子硬实率高的耐受性好,而发芽率高的并不代表种子活性也高。

关键词: 苜蓿, 硬实种子, 人工老化