刺槐生长及盐离子吸收分配对干旱和旱盐胁迫的响应

通过盆栽控制土壤水分和氯化钠质量分数,研究了2个刺槐Robinia pseudoacacia无性系（W1和L78）的生长及体内盐离子分布、选择性吸收（运输）离子对干旱和旱盐胁迫的响应,探讨了W1和L78对2种胁迫响应机制的异同及抗旱与耐盐间的相互关系。研究表明：①2种胁迫均抑制了2个无性系的生长。干旱胁迫对W1生长的抑制作用强,而旱盐胁迫对L78生长的抑制作用强。②2种胁迫下,L78根的RK,Na,RCa,Na和RMg,Na比W1的小,而叶的RK,Na,RCa,Na和RMg,Na大,造成根中K^＋,Ca^2＋和Mg^2＋的匮乏,是2种胁迫抑制L78生长的共同原因。L78根控制Na＋吸收和向地上部运输的能力差,是旱盐胁迫进一步抑制L78生长（与干旱胁迫相比）的原因之一。③在旱盐胁迫下,W1能维持相对稳定的矿质营养水平,尤其是K＋和Ca^2＋,同时根系对Na＋的吸收和向地上部的运输有较强的控制能力,表现出较强的抗旱耐盐能力。④干旱胁迫下,W1根中离子总量降低幅度较L78大,表明无机离子在渗透调节中所占的比重较L78小,表明有机渗调作用加强,加大了自身物质和能量的消耗,造成干旱胁迫抑制W1生长的作用较L78大。表5参15

Growth,ionic absorption and ionic distribution responses to soil drought and drought-salt stresses in two Robinia pseudoacacia clones

Growth,ionic distribution and selective ionic absorption(transportation)responses to soil drought stress alone and drought-salt stress two Robinia pseudoacacia(black locust)clones(W1 and L78)were determined.The salt and drought stresses were set by controlling the amount of NaCl and water in potted plants.Results showed that both stresses inhibited growth of the two clones with drought-salt stress inhibiting growth more than drought stress alone.In addition,drought stress alone inhibited growth more on W1 than on L78,whereas drought-salt stress inhibited growth more on L78 than on W1.Also,under drought stress,total Na ,K ,Ca2 and Mg2 content in W1 roots had a greater decline than L78.With both stresses the growth of L78 was inhibited due to low RK,Na(relatively selective ratio),RCa,Na,and RMg,Na rates of L78 roots and large rates for leaves causing a severe decreasing of K ,Ca2 ,and Mg2 in the roots.Contributing to low ion levels was root inability to control both Na absorption and Na transportation to shoots.W1 had higher drought-salt resistance because it maintained a relatively stable mineral nutrient level,especially with K and Ca2 ,and because under drought-salt stress its roots were able to control Na absorption and Na transportation to the shoots.The lower Na ,K ,Ca2 ,and Mg2 in W1 roots compared to L78 under drought stress alone was due to a decrease in the proportion of inorganic oins in osmotic adjustment and an increase in organic ions.This,then,increased consumption of own substances and energy leading to greater inhibition on W1 growth.Ch,5 tab.15 ref.]