Mechanism of exogenous calcium alleviating drought stress damage to Fraxinus malacophylla seedlings
To investigate the damage mechanism of exogenous calcium in alleviating drought stress on the photosynthetic pigments and leaf anatomical structure of Fraxinus malacophylla seedlings.In the present study,a two-factor completely randomized block test was conducted using 2-year-old F.malacophylla seedlings,with factor 1 being the degree of drought with four drought levels,normal(80±5)％,mild drought(65±5)％,moderate drought(50±5)％,and severe drought(35±5)％,and factor 2 beings exogenous CaCl2 with four levels(0,25,50,and 75 mmol·L-1).Measure the leaf characteristics and photosynthetic pigments of F.malacophylla seedlings,and use the bare handed and paraffin sectioning methods to measure the thickness of the upper and lower epidermis,leaf thickness,and the thickness of the palisade tissue of the leaves.The results showed that during the same drought period,the leaf traits,photosynthetic pigments[chlorophyll a,chlorophyll b,and chlorophyll(a+b)],leaf thickness,upper and lower epidermal thickness,and palisade tissue thickness of F.malacophylla seedlings all showed an increasing trend followed by a decreasing trend with the increase of calcium concentration,and the best relief effect was achieved with a treatment of 25 mmol·L-1.During normal water and mild drought periods,the chlorophyll a/b value chang-es in a"V"shape with increasing calcium concentration.Under the same calcium concentration,the leaf traits,photosynthetic pigments,leaf thickness,and palisade tissue thickness of F.malacophylla seedlings showed a significant downward trend with the deepening of drought severity.Applying 25 and 50 mmol·L-1 calcium effectively improved the drought resistance of F.malacophylla seedlings.The correlation analysis showed that there was a highly significant positive correlation between leaf traits,photosynthetic pig-ments,leaf thickness,and palisade tissue thickness.
NETL
NSTL
万方数据
