Alleviating Effects Of Exogenous Ca²⁺ On Zoysia Japonica Under Drought Stress

As a kind of common lawn grass, Zoysia japonica is drought resistance anddistributed throughout China. Drought is the most common and one of the mostimportant factors affecting the growth of plants. Drought stress significantlyrestrained the growth of plants, reduced photosynthesis and enzymatic activity. Manyresearches indicated that plants have defenseless of mild to moderate stress, butsevere stress can cause drooping and dying of plants. There is a lot of researchesindicated that exogenous substances can alleviate the drought damage to plants. CaCl₂as an exogenous substances, has been applicated in resistance of plants drought for along time. CaCl₂can suppress plant transpiration and mitigate the impact of droughton plants. Therefore, through the analysis of growth index, photosynthesis andfluorescence indexes, and enzymatic activity index under drought stress and CaCl₂, tounderstand the alleviate effects of CaCl₂to Zoysia japonica.In this experiment, Zoysia japonica as the test material, using natural droughtand weighing method to drought stress. The experimental treatment were divided intofour groups: CK was pretreated with distilled water; T1was pretreated with5mmol/LCaCl₂; T3was pretreated with10mmol/LCaCl₂; T3was pretreated with20mmol/LCaCl₂; Then Zoysia grass were natural drought treated.The results showed that: From the early to mid stage of drought stress （0-6days）,Zoysia japonica has drought resistance ability, activity of enzyme system andphotosynthesis enzyme system enhanced, fluorescence parameters rised. Effects ofCaCl₂solution was not obvious. Stress in the later period （6-16days）, enzyme system,photosynthesis and parameters of CK group decreased, while the pretreatments ofCaCl₂groups were gentle, effects of CaCl₂pretreatments significantly increased.Pretreatment CaCl₂promoted photosynthesis inhibition of Zoysia japonica, risedfluorescence parameters, reduced intracellular MDA content, increased Pro content,and enhanced the activity of antioxidant enzymes.To sum up, Zoysia japonica has very strong defensive ability on mild andmoderate drought stress, but severe drought stress would cause serious damage to it. Exogenous CaCl₂can effectively alleviate the severe stress on Zoysia japonica. Theresult of10mmol/LCaCl₂was the best.