土壤干旱对黄土高原3个常见树种幼苗水分代谢及生长的影响

应用盆栽试验,在人工控制土壤水分条件下对黄土高原3个常见树种丁香(Syringa oblata)、杠柳(Perip-loca sepium)和连翘(Forsythia suspensa)幼苗的生长及水分生理代谢进行了研究.结果表明,随干旱胁迫程度加剧,各树种耗水量明显减少;不同树种单株耗水量差异明显,表现为:连翘>杠柳>丁香.3树种新生枝条生长和叶面积扩展速率明显受土壤含水量影响,均表现为适宜水分>中度干旱>严重干旱,且在同一胁迫水平下,连翘>杠柳>丁香.随干旱胁迫程度的加剧和干旱时间的延长,丁香、杠柳和连翘叶片的含水量、游离脯氨酸以及叶绿素含量均有不同程度的变化,连翘和杠柳的叶片含水量在3种水分条件下均明显高于丁香,杠柳叶片游离脯氨酸含量明显高于丁香和连翘,连翘体内脯氨酸含量最低,丁香和连翘的叶绿素a/b值随土壤含水量的减少逐渐降低,杠柳则表现出相反趋势.不同树种对土壤干旱和高温的响应机制不同,但它们都具有较强的抗旱能力,适应黄土高原干旱的自然条件.

Effect of Soil Drought on Seedling Growth and Water Metabolism of Three Tree Species in Loess Plateau

The growth and water metabolism of three tree species on the Loess Plateau was studied under soils with different water contents.The results showed that water consumption of those species decreased with the increase of drought stress,and water consumption of those tree species was different:Forsythia suspensa was the greatest and Syringa oblata was the lowest.The growth rate of new branches and leaf area of the three native tree species were the fastest under adequate soil water conditions,and were the lowest under severe drought.Under the equal water conditions,the growth of F.suspense was fastest while S.oblata was the slowest.The water content,proline and chlorophyll content of different species changed with the increase of soil water stress.The leaf water content of P.sepium and F.suspensa were higher than that of S.oblata obviously,while the leaf proline content of F.suspensa and S.oblata were lower than that of P.sepium.The leaf chlorophyll a/b ratio of F.suspensa and S.oblata decreased with the decrease of soil water content.Although these three tree species had different mechanism in response to drought stress,they all had higher drought resistance and could adapt to the drought condition in Loess Plateau.The result provided some basis of chosing tree species in Loess Plateau.