PEG胁迫对文冠果种子萌发和幼苗生理特性的影响

在种子发芽箱中,以清水为对照,用5%、10%、15%、20%、25%、30%和35%共7个浓度聚乙二醇(PEG-6000)溶液浇灌栽培基质,观察文冠果种子的萌发和幼苗生长情况,以及幼苗叶片脯氨酸、丙二醛的含量和细胞膜相对透性的变化,探讨文冠果种子萌发对土壤水分的要求及其幼苗忍耐干旱的能力。结果显示:(1)在PEG浓度5%～35%范围内,文冠果种子发芽率、成苗率、幼苗根长和细胞膜透性均随着胁迫强度的增加呈明显的下降趋势;细胞膜透性随着胁迫强度的增加先升高后降低,但脯氨酸、丙二醛含量和幼苗根数量则呈现逐渐上升趋势。(2)5%的PEG浓度能够促进文冠果种子萌发,提高成苗率和根数量,降低幼苗死亡率;5%～10%的PEG能够明显促进苗高生长,但对根长影响不大;当PEG浓度高于15%后,种子萌发受到抑制,成苗率明显降低。(3)当PEG浓度高于25%时幼苗死亡率急剧上升,幼苗脯氨酸含量、丙二醛含量和细胞膜透性显著增加,细胞膜结构受到严重伤害。研究表明,低浓度PEG处理有利于文冠果种子萌发和幼苗生长,但过高浓度却对文冠果种子萌发和幼苗生长具有一定的抑制作用;文冠果种子萌发及其幼苗可忍受5%～25%的PEG渗透胁迫,即文冠果种子萌发和幼苗生长可忍受土壤水势为-7.94～-11.05MPa的干旱胁迫。

Effect of PEG Treatment on Seed Germination and Growth of Seedlings of Xanthoceras sorbifolia

To determine the germination and morphological response of Yellow Horn (Xanthoceras sorbifolia) to soil moisture and drought stress,seed germination and seedling growth of Yellow Horn were assessed under controlled conditions that simulated drought stress induced by polyethylene glycol (PEG-6000) in seed germination box.Water stress was supplied through incubation in seven different concentrations (5%,10%,15%,20%,25%,30% and 35%) of PEG-6000 that provide solutions with water potentials being separately -0.58,-1.66,-3.25,-5.34,-7.94,-11.05 and -14.66 MPa.The experiment was designed as a completely randomized design with one factor.The results showed that:(1)The germination capacity,planting percent,root length and relative permeability of cell membrane decreased with a decrease in osmotic potential,whereas free proline content,MDA content and the number of roots of seedling increased.(2)The seed germination,planting percent and the number of roots in 5% of PEG concentration was higher than that of control treatment,and mortality was lower.At the same time,seedling height in 5%~10% of PEG concentreation was higher than that of control treatment,but did not differ significantly from control.(3)More dramatic differences between PEG concentration were evident when the effects of water stress on seed germination,planting percent,mortality,root length,the number of roots and free proline content,MDA content and relative permeability of cell membrane were evaluated.These findings form the rang of water potential which Yellow Horn can suffer from was -7.94~-11.05 MPa.