Effects Of Calcium Fertilizer And Magnesium Fertilizer On Photosynthetic Characterstics And Nutrient Of Toona Ciliata Var.Pubescens

Toona ciliata var.pubescens is a plant of Toona.which with high development prospect and economic value.It is an ideal fast-growing and high-yielding tree species and a national secondary protected plant.The soil nutrient status is plays a decisive role in the stand growth of T.ciliata var.pubescens.And plantation forestry soil nutrient status in our country is poor,cannot satisfy the plantation fast-growing high nutrient requirements,the soil calcium and magnesium is serious,therefore the plantations of T.ciliata var.pubescens common growth is not good.Fertilization is an important means to improve the stand of artificial forest.Studying the effects of calcium and magnesium fertilizer on the growth and nutrients of T.ciliata var.pubescens is of practical significance for rational application of calcium and magnesium fertilizer and improvement of the benefits of T.ciliata var.pubescens plantation.Therefore,in this study,set up the calcium fertilizer,magnesium fertilizer to two factors,three levels,a total of nine treatments,the effects of calcium and magnesium fertilizer on the growth and development,photosynthetic physiology and the absorption of mineral elements of T.ciliata var.pubescens were studied,and the response mechanism of T.ciliata var.pubescens to calcium and magnesium fertilizer was elucidated,so as to provide theoretical basis for the rational fertilization of T.ciliata var.pubescens.The main results are as follows:（1）Calcium and magnesium fertilizer significantly promoted the growth of seedling height and ground diameter.Calcium and magnesium fertilizer is beneficial to improve the leaf length,leaflet width,leaflet number and leaf axis length of T.ciliata var.pubescens,so as to improve leaf area.Among them,the level of Ca₃ and Mg₃ is beneficial to the improvement of leaf index values such as leaf area,leaf axis length and leaflet number of T.ciliata var.pubescens.Among them,Ca₂Mg₃ treatments is the best.Calcium fertilizer promoted the synthesis of T.ciliata var.pubescens protein.Magnesium fertilizer inhibits protein synthesis.Under the condition of magnesium fertilizer application,the rational application of calcium fertilizer can increase the content of soluble protein.（2）Calcium and magnesium fertilizer can increase the chlorophyll content of T.ciliata var.pubescens,and the interaction of calcium and magnesium fertilizer has a significant effect on the chlorophyll content of T.ciliata var.pubescens.The rational application of calcium and magnesium fertilizer can increase the chlorophyll content of T.ciliata var.pubescens and maintain it at a high level for a long time.Among them,the content of chlorophyll a,chlorophyll b and chlorophyll in Ca₃Mg₁ treatment was the highest,followed by Ca₂Mg₃.Calcium and magnesium fertilizer can increase net photosynthetic rate,but not obviously.Magnesium fertilizer can improve the stomatal conductance of T.ciliata var.pubescens,and the stomatal conductance（Gs）at low calcium and magnesium levels is the highest.Both calcium and magnesium fertilizer could significantly improve the intercellular CO₂ concentration（Ci）and transpiration rate（Tr）of T.ciliata var.pubescens.The results showed that the application of proper calcium and magnesium fertilizer could increase the chlorophyll content and photosynthetic rate,and promote the photosynthesis.（3）Calcium and magnesium fertilizer can improve the biggest fluorescence of T.ciliata var.pubescens hand.-mazz（Fm）,PSⅡpotential quantum yield（Fv/Fo）and PSⅡmaximum quantum yield（Fv/Fm）,but the application of magnesium fertilizer could inhibit the Fm of T.ciliata var.pubescens under the condition of calcium fertilizer application.Proper calcium and magnesium fertilizers can improve light energy utilization（α）,maximum electron transfer rate（ETRmax）and tolerance to strong light（Ik）.The results showed that proper amount of calcium and magnesium fertilizer could improve the light energy conversion rate of T.ciliata var.pubescens.Treatment with7（Ca₃Mg₁）was the best.（4）Calcium fertilizer inhibited the absorption of nitrogen in the root system and leaves of T.ciliata var.pubescens,while magnesium fertilizer inhibited the absorption of N in the plant of T.ciliata var.pubescens.The interaction of calcium and magnesium fertilizer had a significant effect on the accumulation of P content in various organs of T.ciliata var.pubescens,and the rational application of calcium and magnesium fertilizer could significantly increase the P content in the roots,stems and leaves of T.ciliata var.pubescens.Calcium and magnesium fertilizer can inhibit the absorption of K in roots,stems and leaves,but not obviously.The Proper amount of calcium fertilizer can increase the content of Ca in various organs of T.ciliata var.pubescens,but it is not significant.Proper amount of magnesium fertilizer is beneficial to the absorption of Ca by the root system of T.ciliata var.pubescens,while magnesium fertilizer inhibits the absorption of Ca by the stem and leaves of T.ciliata var.pubescens.The proper amount of calcium fertilizer promoted the absorption of Mg in the root system and leaves of T.ciliata var.pubescens,inhibited the absorption of Mg in the stem,and the appropriate amount of magnesium fertilizer promoted the absorption of Mg in the root system,stem and leaves of T.ciliata var.pubescens,but it was not obvious.