入侵植物长刺蒺藜草对不同程度干旱胁迫的适应对策

Adaptive countermeasures of invasive plant Cenchrus longispinus to different degrees of drought stress

研究长刺蒺藜草在逆境条件下的生理适应机制,明确其抗旱能力,对防治长刺蒺藜草有重要意义。本研究选择内蒙古自治区通辽市科尔沁沙地长刺蒺藜草的成熟期刺苞中的种子为材料,模拟不同程度的干旱胁迫,通过室内盆栽试验方法进行处理,设置3个水分处理梯度,土壤含水量分别控制在田间饱和持水量的80%、55%和35%,分别研究恒定的充分供水处理(CK)、中度干旱胁迫处理(MD)、重度干旱胁迫处理(SD)对长刺蒺藜草各器官生物量、保护酶活性及丙二醛含量的影响。结果表明:(1)随着干旱胁迫程度增强,长刺蒺藜草的茎、叶生物量以及地上总生物量均逐渐减少,果实生物量呈现先增长后减少的趋势。(2)随干旱胁迫程度的加强,长刺蒺藜草的过氧化物酶(POD)活性、丙二醛(MDA)含量迅速上升;超氧化物歧化酶(SOD)活性平缓上升;过氧化氢酶(CAT)活性呈先上升后下降。(3)中度干旱胁迫下长刺蒺藜草的生育期与充分供水的无显著差异且显著长于重度干旱胁迫下的。综上所述长刺蒺藜草在中等干旱胁迫下采用耐旱的适应策略,降低营养体的生物量分配,增加繁殖体的生物量分配并且延长生长发育时间从而获得更大的结实量;而在重度干旱胁迫下采用逃旱的适应策略,营养体的生物量分配进一步降低,向繁殖体的转化率增加,在较短的时间内快速完成生活史周期,获得更大的繁殖成功率。

It is of great significance to study the physiological adaptation mechanism of Cenchrus longispinus under adversity conditions and clarify its drought resistance. The seeds from C. longispinus burs at mature period in Horqin sandy land of Tongliao City,Inner Mongolia Autonomous Region were collected as materials to simulate different degrees of drought stress. Through the indoor pot experiment method,three water treatment gradients were set up,and the soil water contents were controlled at 80%,55% and 35% of the field saturated water capacity,respectively. The effects of constant water treatment(CK),moderate drought stress(MD) and severe drought stress(SD) on the biomass,protective enzyme activity and malondialdehyde(MDA) content of different organs of C. longispinus were studied. The main results were as follows:(1) With the increase of drought stress,the stem biomass,leaf biomass and total above ground biomass of C. longispinus decreased gradually,and the fruit biomass increased firstly and then decreased.(2) With the increase of drought stress,the activity of peroxidase(POD) and the MDA increased rapidly;the superoxide dismutase(SOD) activity increased slowly;the activity of catalase(CAT)increased firstly and then decreased.(3) There was no significant difference in the growth period of C.longispinus under moderate drought stress and sufficient water supply,and it was significantly longer than that under severe drought stress. In summary,under moderate drought stress,C. longispinus adopts a drought-tolerant adaptation strategy to reduce the biomass allocation of nutrients,increases the biomass allocation of propagule,and prolong the growth and development time to obtain greater seed yield. However,under severe drought stress,C. longispinus adopts the adaptation strategy of escaping drought. At the same time,the biomass allocation of its vegetative body is further reduced,and the conversion rate to the propagule is increased,and it can quickly complete the life cycle in a short time,thereby obtaining a greater reproductive success rate.