全 文 ：文章编号: 1007-0435( 2006) 04-0393-02 ·博士论文摘要·
苗期紫花苜蓿对干旱胁迫的适应机制
博士生 : 韩瑞宏 导师: 卢欣石
(北京林业大学, 北京 100083)
紫花苜蓿(Medicago sativa) (以下简称苜蓿)
是重要的豆科牧草,在世界分布广泛。本研究以强
抗 旱性 ( 陇 东 苜 蓿 Medicago sativa L. cv .
Longdong )、中抗旱性(公农1号 M edicago sativ a
L. cv . Gongnong No. 1)及弱抗旱性( BL-02-329)
3种紫花苜蓿为试验材料进行抗旱机制的研究,
主要结果如下:
1.对干旱胁迫下3种苜蓿叶片活性氧清除机
制的研究结果表明,干旱胁迫会造成苜蓿叶片活
性氧产生速率增大、丙二醛含量增多、细胞膜透性
增大。与抗旱性弱的相比,抗旱性强的苜蓿叶片活
性氧产生速率低, 丙二醛含量积累少, 细胞膜受到
的破坏较轻。同时, 在干旱胁迫下, 3种苜蓿叶片
SOD、POD两种保护酶活性增高、非酶抗氧化物
类胡萝卜素和抗坏血酸含量增多, 抗旱性强的苜
蓿酶系统与非酶系统内部协调性强。
2. 在干旱胁迫下, 3种苜蓿叶片水分代谢及
部分渗透调节物质的变化结果表明, 干旱胁迫使
苜蓿叶片水势和叶片组织相对含水量降低, 水分
饱和亏缺及束缚水含量增加。抗旱性强的苜蓿叶
片水势降低幅度大,叶片组织含水量下降幅度及
叶片水分饱和亏缺增加的幅度小, 束缚水与自由
水的比值增加幅度大, 维持正常水分状况的能力
强。同时叶片脯氨酸及可溶性糖两种主要渗透调
节物质的含量增加,其中脯氨酸增加明显(在抗旱
品种中成百倍地增加) , 陇东苜蓿在控水的第 12
天可溶性糖含量降低时,脯氨酸含量最大, 脯氨酸
在干旱后期的大量积累可能是可溶性糖含量下降
的补偿策略。
3. 在干旱胁迫下, 3种苜蓿净光合速率、蒸腾
速率、气孔导度都有较大幅度下降,气孔导度和蒸
腾速率间呈极显著正相关。抗旱性强的苜蓿随干
旱胁迫程度的加深,净光合速率下降较慢。研究表
明,轻度干旱胁迫下, 气孔限制是3种苜蓿光合作
用降低的主要因素;中度和重度干旱胁迫下净光
合速率降低, 非气孔限制起着主要作用。
4. 苜蓿叶绿素荧光的测定结果表明, 在干旱
胁迫下, 3种苜蓿PSⅡ反应中心光化学效率( Fv /
Fm )、PSⅡ潜在活性( Fv/ Fo)降低。总体上抗旱性
强的苜蓿Fv/ Fm 和Fv/ Fo 下降幅度小, PSⅡ利用
光能的能力及PSⅡ的潜在活性强。在干旱胁迫
下, 光化学淬灭系数 ( qP )、非光化学淬灭系数
( qN )的变化表现为 3种苜蓿qP 值降低、qN 值升
高,总体上抗旱性强的苜蓿qP 降低幅度低, qN 升
高幅度大,表明干旱胁迫下抗旱性强的苜蓿叶片
PSⅡ反应中心电子传递活性受到的影响小,光合
机构的损伤程度低。
5. 在干旱胁迫下,陇东、公农1号、BL-02-329
3种苜蓿叶片ABA、IAA 含量均有不同程度的上
升, GA 3 和ZR的含量均呈下降趋势。在干旱胁迫
下, 4种内源激素之间的协调总趋势是向着气孔
关闭、促进根系发展的方向进行。
关键词: 苗期; 紫花苜蓿; 干旱胁迫; 适应机制; 活性氧产生与清除; 渗透调节; 内源激素; 光合生理
中图分类号: S812 文献标识码: A
完成时间: 2006年3月
收稿日期: 2006-10-30; 修回日期: 2006-11-09
作者简介: 韩瑞宏( 1974-) ,女,内蒙古牙克石市人,农学博士,研究方向为牧草抗性生理, E-mail: hr hf ly@ 126. com
导师简介: 卢欣石( 1947-) ,男,教授,主要从事草地资源与生态方面研究, E-mail : luxinshi@ soh u. com
第14卷 第 4期
Vo l. 14 No . 4
草 地 学 报
ACT A AGRESTIA SIN ICA
2006年 12 月
Dec. 2006
Studies on Adaptive Mechanism of Alfalfa in Drought Stress at Seedling Stage
Candidate: Han Rui-hong Advisor : LU Xin-shi
( Institute o f Resour ce and Envir onment, Beijing Fo restr y Univ er sity, Beijing 100083, China)
Alfal fa ( Medicago sativa) , a very impo rtant kind o f for age, is w idely planted. Studies reco rded in the
pr esent paper on three alfalfa germplasm r esources: Longdong ( st rong drought-resistant ) , Gongnong No1
( medium drought resistant ) , and BL-02-329 ( w eak drought resistant ) , w ere selected to explore the adapt ive
mechanism of alfal fa under drought st ress. T he main results o f research are as follow s:
1. A study on act iv e oxygen generat ion and clearing mechanism in leaves o f the thr ee alfalfa cultivars
show s: Under drought st ress, the leaf act ive oxygen gener ation rate, malondiatdehyde content , and damage of
cell membrane increased. Compared to the w eak drought-resistant alfalfa cul tivar , leaf of the st rong drought
resistant alfalfa gener ated less act ive oxygen, and accumulated less malondiatdehyde, and its cell membrane
w as less damaged. At the same t ime, the leaf SOD, and POD act iv ity enhanced, and the ant ioxidat ion
substance, carotenoid and ascorbic acid, increased. M oreover , the endogenous coo rdination of enzyme sy stem
and non-enzyme system in the leaf of the st rong drought-resistant alfalfa w as w ell regulated.
2. Results o f the study on w ater metabol ism and osmot ic adjustment substance in the leaves o f the thr ee
alfalfa cult ivars show that , under drought st ress, the leaf w ater potent ial and w ater relat ive content decr eased,
w hile the water saturat ion deficit and bound w ater content increased. T he st rong drought- resistant alfalfa
boasted the abil ity to keep no rmal w ater state under drought st ress, and to maintain gr eater ex tent of low water
po tent ial, limited extent of decreased w ater relat ive content and of w ater saturat ion def icit , while the r at io of
bound w ater content to f ree water content in the leaves increased. At the same t ime, the content of pro line and
so luble sugar w hich are tw o main osmot ic adjustment substances increased. M ore part icularly , the pro line
content in the leaves of the st rong drought-resistant alfalfa under drought st ress rose a hundred t imes than
before. On the 12 th day under dr ought str ess, the proline content of leaves o f Longdong alfalfa reached the
highest , and the soluble sugar content reduced. In the later drought st ress period, the rich accumulat ion of
pr oline content could offset the reduct ion o f soluble sugar content .
3. The net photosynthet ic rate, t ranspirat ion rate, and stomatal conductance of leaves of the three alfalfa
cult ivars under dr ought st ress decreased dramat ically. A positive co rrelation existed between stomatal
conductance and transpir at ion. Compared to the weak drought-resistant alfalfa under intense drought st ress,
the net pho to synthet ic r ate of leaves of the st rong drought-resistant alfalfa descended slow ly . Stomatal
rest rict ion w as the main factor causing the net photosynthetic rate to decrease in the leaves of the three alfalfa
cult ivars under slight drought st ress, whereas under medium or serious drought st ress, the non-stomatal
rest rict ion became the main factor inducing the net photosynthesis to decrease in the leaves of the three alfalfa
cult ivars.
4. Measuring the chlorophyll fluorescence of leave o f the thr ee alfalfa cultivar s under drought st ress
show ed that their PSⅡFv/ Fm and Fv/ Fo decreased. How ever, the st rong drought resistant alfalfa decreased
less in Fv/ Fm and Fv / Fo and its PSⅡ capability of l ig ht ut ility and potential act iv ity w as higher than tho se of
the o ther tw o alfalfa cul tivars. T he three alfalfa Quenching ( qP) of chlo rophy ll f luo rescence decr eased and Non-
photochem ical Quenching ( qN) of chlorophy ll fluorescence increased. What s more, the fact that qP decreased
less and qN increased more in the leaves of the st rong drought-resistance alfalfa pr oved that the elect ron
t ranspo rt act ivity and photosynthesis apparatus damaged less the leaves of the st rong drought-resistant alfalfa
than the other tw o cultiv ar s.
5. T he study on the endogenous hormones content in leaves of the three al falfa cult ivars show s: Under
dr ought st ress the content of ABA and IAA in the leaves of the three alfalfa cult iv ar s increased and the content
of GA3 and ZR decreased at dif ferent ex tents The general tr end of co ordination among the four endogenous
hormones w as closing the stomas and pr omot ing the g row th of ro ots.
Key words : Seedling stage; Alfal fa; Dr ought resistance; Adapt ive mechanism ; Act ive oxygen gener at ion
and clear ing ; Osmot ic adjustment ; Endogenous hormones; Pho to synthet ic physiolog y
(责任编辑 才 杰)
394 草 地 学 报 第 14卷