梭梭和头状沙拐枣形态及生理生化特性对干旱胁迫的响应

Physiological,biochemical and morphological responses of Haloxylon ammodendron and Calligonum caput-medusae to drought stress

目前,干旱和沙漠化等生态问题对植物的生存和适应提出新挑战。因此,探索植物的干旱适应策略对沙漠人工生态系统的维护和可持续发展具有重要意义。本研究采用灌溉(CK)和干旱(D)两个处理,研究塔克拉玛干沙漠防护林梭梭(Haloxylon ammodendron)和头状沙拐枣(Calligonum caput-medusae)生理生化和形态的适应情况。结果表明:形态上,两种植物的同化枝在干旱胁迫下均显著变短变细;生理上,两种植物在干旱胁迫下光合参数和羧化过程无显著变化,同化枝黎明水势显著降低,头状沙拐枣同化枝正午水势显著降低;生化上,两种植物的叶绿素a、叶绿素b、总叶绿素、光合酶含量在干旱胁迫下无显著变化。两种植物的初始荧光、最大荧光显著降低,梭梭的PSⅡ最大光化学效率显著升高。以上研究表明,两种植物以减缓同化枝生长和维持碳同化的方式抵御干旱。两种植物在干旱胁迫下光合色素活性降低,激发能力下降。头状沙拐枣稳定的叶绿素含量,使光化学系统免受损伤。

Desertification and drought have emerged as global ecological issues,which pose significant difficulties for plant adaptability and survival.Consequently,it is crucial to investigate the adaptation mechanisms of plants to drought stress to preserve and grow sustainably artificial ecosystems in desert regions.This study examined the physiological,biochemical,and morphological responses of Haloxylon ammodendron and Calligonum caput-medusae in the Taklimakan Desert shelterbelt by employing two treatments:irrigation(20-day irrigation cycle)(CK)and drought(D).The findings demonstrated that under drought stress,the assimilatory branches of both plants were noticeably shorter in terms of morphological traits.The branches of both were also significantly thinner.Regarding physiological reactions,there were no notable distinctions between the two in terms of the photosynthetic gas exchange parameters and the leaf dry mass during drought stress.Additionally,the carboxylation processes,metabolic reaction rates,chlorophyll a,chlorophyll b,total chlorophyll,and photosynthetic enzyme contents of both did not exhibit any appreciable alterations under drought stress.However,both showed substantially reduced Fm and Fo values.The Fv/Fm values of H.ammodendron were noticeably greater,but those of C.caput-medusae did not change much.According to our study,H.ammodendron and C.caput-medusae were able to adapt to drought by reducing the assimilate-branch growth,excitation capacity,and photosynthetic pigment activity,thereby preserving photosynthetic capacity.The photochemical system of C.caput-medusae was less vulnerable to damage due to a stable chlorophyll concentration.