外源脱落酸、水杨酸对小麦种子萌发及生理特性的影响

Effect of exogenous abscisic acid and salicylic acid on germination and physiological characteristics of wheat seed

穗发芽严重降低籽粒产量、品质和种用价值,是小麦育种和生产急需解决的难题.为利用发芽抑制剂的化控途径有效防治穗发芽,研究了不同浓度的外源激素脱落酸(ABA)、水杨酸(SA)对种子发芽的抑制作用及其生理生化响应.结果表明:浓度大于70 mg L-1 ABA和大于4 mmol L-1 SA均不同程度地抑制种子发芽并表现剂量效应,赤霉素对二者有拮抗作用,70 mg L-1 ABA+8.0 mmol L-1 SA对小麦普遍具有强烈的发芽抑制效应;ABA阻抑种子发芽是一种延缓作用,受基因型影响较大;SA对不同基因型有强烈的休眠促进作用,并显著提高种子对ABA的敏感性(P<0.01);种子萌发过程中,两种激素均诱导籽粒α-淀粉酶和PPO活性下降,且SA处理组的酶活性降幅更大;ABA明显促进种子PAL活性,而SA处理组的PAL活性水平最低.因此,ABA与SA的发芽抑制效应与作用方式不同,SA增强种子的ABA敏感性,二者组合产生了良好、稳定的发芽抑制效果.

Pre-harvest sprouting （PHS）, which causes devastating damage to grain yield and end-use quality, is a serious problem for wheat breeding and production in the world. Exogenous abscisic acid （ABA） and salicylic acid （SA） were used to study the effect of applied hormones on wheat seed germination, and the physiological chemistry of germinated seeds after hormone treatment. The results showed that both ABA （〉 70 mg L-1） and SA （〉 4 mmol L-1） blocked wheat seed germination in a dosage dependent manner whereas gibberellin antagonized the inhibitory effects slightly. Co-application of 70 mg L~ ABA and 8 mmol L-~ SA commonly caused intensive germination inhibition without genotype-dependent variation. ABA displayed stronger germination inhibition on ABA-sensitive wheat genotypes than on ABA-insensitive ones, probably caused by postponing germination process. Comparatively SA showed more intensive effect on germination inhibition, with no correlation between inhibitory effects and wheat genotypes. SA significantly inhibited the transfer of seed development from dormancy to germination, and had noticeably positive effect on plant ABA sensitivity for inhibition of seed germination （P 〈 0.01）. During seed germination, activities of alpha-amylase and polyphenol oxidase （PPO） decreased significantly when treated by either ABA or SA, with lower activity levels in SA group. Compared with the control, ABA significantly promoted phenylalanine ammonialyase （PAL） activity whereas SA group showed the lowest level of PAL activity. In conclusion, ABA and SA have different effect on seed germination in terms of inhibition extent and underlying mechanisms.SA increases seed sensitivity to ABA, and the hormone combination causes stable and intensive germination inhibition.