甘草叶片形态结构和光合作用对干旱胁迫的响应

叶片结构在植物防御生物和非生物胁迫方面起着重要的作用,可通过合成、储存和分泌次生代谢产物提高植物抗性。以甘草幼苗为试材,采用盆栽控水自然干旱法,探讨叶片光合作用、气孔微形态和腺体形态对干旱胁迫的响应。结果表明:①随着干旱胁迫程度的加剧,叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均呈先升高后降低的趋势;其中胞间CO2浓度(Ci)在重度干旱胁迫(severe stress,SS)时迅速增高。②随着干旱胁迫程度的加剧,叶片总气孔密度和气孔开张比呈先增大后减小的趋势;而气孔开张宽度呈逐渐减小的趋势。③随着干旱胁迫程度的加剧,叶片上表皮和下表皮腺体密度总数整体上呈增大的趋势,腺体颜色随着干旱胁迫程度的加剧逐渐加深,形状出现不规则褶皱和内陷。总之,甘草叶片表面的腺体特征参与抗旱逆境调节,从而避免干旱胁迫对甘草植株的伤害;在SS下,胁迫程度加速了气孔细胞的程序性死亡(PCD),甘草幼苗失去抗旱能力。

Response of Photosynthesis and Leaf Morphological Characteristics to Drought Stress in Glycyrrhiza uralensis

The changes of photosynthesis,stomatal changes and glandular morphologic of leaves in Glycyrrhiza uralensis were measured with pot-culture drought stress in greenhouse,and the drought resistance of them wereevaluated by membership function and drought resistance coefficient.The response of leaf photosynthesis,stomatalmicromorphology and glandular morphology to drought stress was studied by pot controlled water natural droughtmethod.The results showed that leaf net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)have been rising since the degree of drought resistance after the trend of lower,and the intercellular CO2(Ci)concentration increased rapidly in the severe drought stress.Moreover,leaf total stomata density and stomataopening than with the intensification of the degree of drought stress,the trend of first increases and then decreases,and stomatal opening width is gradually decreasing trend.Importantly,since the degree of drought stress,leafepidermis and lower epidermis gland density overall showed a trend of increase in the total number of gland color asthe degree of drought stress increased gradually deepened,shape appears irregular fold and retraction.Theglandular characteristics on the leaf surface of G.uralensis are involved in the regulation of drought resistance,so asto avoid the damage of drought stress to G.uralensis.Under severe drought stress,stress accelerated theprogrammed death of stomatal cells(PCD),and G.uralensis seedlings lost their ability to resist drought.