多年生黑麦草叶片形态与低温胁迫的生理响应

多年生黑麦草(Lolium perenne)在冬季低温多风条件下易受寒害影响,造成脱水死亡。本研究以抗寒性强品种‘Brightstar SLT’和抗寒性弱品种‘Linn’为试验材料,在自然状态下观察两种黑麦草叶片形态,测定叶片相对失水速率,并在0℃低温胁迫条件下测定相关生理指标,以探究多年生黑麦草叶片形态与其低温胁迫生理响应的关系。结果表明,自然状态下,‘Brightstar SLT’叶片气孔数量显著多于‘Linn’(P0.05),气孔长度、气孔面积、叶片表皮细胞和相对失水速率显著小于‘Linn’(P0.05)。低温胁迫后,两品种多年生黑麦草蒸腾速率和气孔导度在短时间内均升高,‘Brightstar SLT’蒸腾速率和气孔导度显著小于‘Linn’(P0.05),光合速率显著高于‘Linn’(P0.05),电解质渗透率低于‘Linn’。由此得出:抗寒品种失水速率慢,在低温胁迫条件下表现出光合能力稳定和受低温伤害程度低的特点与其气孔数目多、长度小、面积小和表皮细胞小的叶片形态紧密相关。

Relationship between leaf morphology and physiological responses of perennial ryegrass under cold stress

Perennial ryegrass(Lolium perenne )is susceptible to cold and windy condition in winter,which re-sults in dehydration and death.In order to explore the relationship between leaf morphology and physiological changes of perennial ryegrass under cold stress,leaf morphology,relative water loss rate of detached leaves and some physiological indices under cold stress 0 ℃ of cultivar ‘Brightstar SLT’(freezing-tolerant)and ‘Linn’ (freezing-sensitive)were measured.Under natural condition,the stomatal number of ‘Brightstar SLT’was significantly higher than (P ﹤0.05)that of ‘Linn’,whereas stomatal length,stomatal area,leaf epidermal cell and leaf relative water loss of ‘Brightstar SLT’were significantly lower than (P ﹤0.05)those of ‘Linn’.Un-der cold stress,transpiration rate and stomatal conductance of both perennial ryegrass cultivars increased in a short time,however,those of the ‘Brightstar SLT’were significantly lower (P ﹤0.05)than those of ‘Linn’. In addition,the photosynthetic rate of ‘Brightstar SLT’was significantly higher (P ﹤ 0.05 )than that of‘Linn’,whereas electrolyte leakage of ‘Brightstar SLT’was lower than that of ‘Linn’.In conclusion,there was a close correlation between lower water loss rate along with better performance under cold stress (including stable photosynthesis ability and less cold injury)and leaf morphology (including larger quantity of stoma, shorter stomatal length,smaller stomatal size and smaller leaf epidermal cell)in freezing-tolerant cultivar.