蒸发脱湿过程中盐胁迫对苜蓿生长及矿质元素吸收运输的影响

Effect of NaCl Stress on Growth and Mineral Element Absorption of clove (Medicago Sativa L.) Seedling during Changes of Soil Moisture

用土壤溶液浓度ＮａＣｌ７５ ～３２５ ｍｍｏｌ／Ｌ的中性盐对苜蓿 进行胁迫处理，研究苜蓿在土壤脱湿过程中，盐胁迫对其生长及矿质元素吸收运输的影响． 结果表明，ＮａＣｌ胁迫浓度的增加和胁迫时间的延长均使苜蓿的相对生长速率、含水量、累积 蒸散量、水分利用效率、Ｋ含量和Ｋ／Ｎａ值下降，但土体中的剩余水量却呈上升趋势．苜蓿生长 受到水分与盐分胁迫双重胁迫的影响．随ＮａＣｌ胁迫的增加，苜蓿的Ｎ素含有率变化不大，但积 累量显著减少；Ｋ＋、Ｃａ２＋的比吸收率（ＳＡＲ）显著降低，植株Ｋ＋、Ｃａ２＋含 量减少，而植株Ｎａ＋、Ｃｌ－的比吸收率ＳＡＲ显著提高，牧草体内Ｎａ＋、Ｃｌ－含量不断积 累增加，植株Ｋ／Ｎａ值降低．对Ｐ、Ｍｇ２＋的吸收在不同水盐条件下变化不一致．苜蓿根系 吸收钾钠离子后，向茎叶运输钾的选择性随ＮａＣｌ胁迫的不同而呈现出不同的趋势．

The grass of Medicago Sativa L. was treated with 25, 75 , 125, 175, 225, 275, 325 mmol/L NaCl in soil for 50 days. The effects of NaCl stress on growth and mineral element absorption by the plant seedling were invest igated dur- ing changes of soil moisture. The results indicated that high NaCl con centration decreased the relative growth rate (RGR), water content of grass, evapotranspiration, water use efficiency (WUE), K content, K/Na ratio, specific absorption rate (SAR) of K and Ca, the contents of K and Ca in plant.However, the residual water in soil was increased. The growth of clover was influenced by water and salt stresses. With the increase of salt stress, nitrogen contents in the clover retained unchanged, but nitrogen accumulation was decreased dramatically. The specific absorption rate of Na and Cl, and the con- tents of Na and Cl in the clover increased continuously and significantly. The uptake of both P and Mg varied inconsistently with the changes of soil water and salt. Additional, after uptake of the K and Na, the selection of K transport to stem and leave was varie d differently with the changes of NaCl stress.