摘要
目的:探讨不同干旱类型对梭梭种子萌发及早期幼苗生长的抑制程度,以期为干旱环境条件下梭梭种苗的高效培育提供科学支撑.方法:以梭梭种子为材料,采用PEG模拟土壤干旱,NaCl模拟生理干旱,通过测定发芽率、发芽势、发芽指数、幼苗活力指数、幼苗长和幼苗根长、根冠比等指标,研究不同等渗梯度(0、-0.46、-1.38、-2.30、-3.23 Mpa)下2种胁迫对梭梭种子萌发及早期幼苗生长的影响.结果:高浓度PEG胁迫(-1.38～-3.23 Mpa)使梭梭种子发芽率、发芽势、发芽指数、幼苗活力指数、幼苗长和根长显著降低,表明中度土壤干旱即可抑制梭梭种子萌发及早期幼苗生长.重度NaCl胁迫(-3.23 Mpa)显著降低发芽率、发芽势和发芽指数,轻度NaCl胁迫(-0.46 Mpa)下幼苗活力指数和根冠比显著高于对照,表明重度生理干旱明显抑制梭梭种子萌发,轻度生理干旱促进梭梭早期幼苗生长.NaCl胁迫比PEG胁迫有更高的发芽率、发芽势、发芽指数、幼苗活力指数、幼苗长和根冠比.结论:土壤干旱和生理干旱显著抑制了梭梭种子萌发及幼苗生长,但土壤干旱抑制作用更强.梭梭更适宜在土壤水势不低于-2.25 Mpa的干旱盐碱地区播种育苗.
Abstract
Objective:To investigate the inhibition degree of different drought types on seed germination and early seedling growth of Haloxylon ammodendron,with a view to providing scientific support for the efficient cultivation of H.ammodendron seedlings under arid environmental conditions.Methods:Seeds of H.ammodendron were used as materials,PEG was used to simulate soil drought,and NaCl was used to simulate physiological drought.The effects of the two stresses under different isotonic gradients(0,-0.46,-1.38,-2.30,-3.23 Mpa)on the seed germination and early seedling growth of H.ammodendron were studied by determining germination rate,germination potential,germination index,seedling vitality index,seedling growth and seedling root length,root-to-head ratio and other indicators.Results:High concentrations of PEG stress significantly reduced the germination rate,ger-mination potential,germination index,seedling vitality index,seedling length and root length of H.ammodendron,indicating that moderate soil drought could inhibit seed germination and early seedling growth of H.ammodendron.Severe NaCl stress(-3.23 Mpa)significantly reduced germination rate,germination potential and germination index,while seedling vitality index and root-to-head ratio were significantly higher than the control under mild NaCl stress(-0.46 Mpa),indicating that severe physio-logical drought significantly inhibited the germination of H.ammodendron seeds,while mild physio-logical drought promoted the growth of H.ammodendron seedlings at early stage.NaCl stress had higher germination rate,germination potential,germination index,seedling vitality index,seedling length and root-to-head ratio than PEG stress.Conclusion:Soil drought and physiological drought sig-nificantly inhibited seed germination and seedling growth of H.ammodendron,but soil drought inhibi-tion was stronger.H.ammodendron was more suitable for sowing seedlings in arid saline areas where the soil water potential not less than-2.25 Mpa.
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