Foliar And Soil Nutrients And Their Stoichiometric Characteristics In Torreya Plantations Based On Different Yield Levels

Torreya grandis cv.Merrillii is an artificially planted variety of species T.grandis Fortune ex Lindley,and is also a valuable economic tree endemic to China.The fruits of T.grandis cv.Merrillii have the functions of moistening lung dryness,promoting digestion and improving spleen and stomach functions,and can improve immunity with long-term use.At present,the Torreya industry is developing rapidly,and becoming one of the leading industries for rural revitalization.The annual output value can reach 10,000 yuan per mu in full fruiting period of Torreya plantation,making its cultivation benefit rank top among the economic forests.However,some problems have also arisen in the development of Torreya industry.In particular,the intensive management such as heavy use of fertilizers and herbicides has caused a series of ecological issues in Torreya plantations,which resulted in a decline in their yield and quality.This poses a serious challenges to the sustainable development of Torreya industry.In this study,an investigation was conducted to reveal the characteristics of soil and foliar nutrients and their stoichiometries of Torreya plantations with different yields:high-,medium-,and low-yielding,and to provide data support and countermeasures for sustainable management of Torreya grandis cv.Merrillii plantations.The major results obtained in this study are as follows.（1）Characteristics of soil physicochemical properties in Torreya plantations with different yields.Soil total phosphorus（TP）content was significantly different among the different yield stands（p<0.05）.Significant differences（p<0.01）were also found in soil acidity（p H）,potassium（K）,calcium（Ca）,magnesium（Mg）,and microbial organic carbon（MBC）contents.There were no significant differences（p>0.05）in soil electrical conductivity（EC）,ammonia（NH₄⁺-N）,nitrate（NO₃^--N）,soluble organic carbon（DOC）,soluble organic nitrogen（DON）,available phosphorus（AP）,microbial organic nitrogen（MBN）,organic carbon（SOC）,and total nitrogen（TN）.The low yielding stands had lowest soil p H,SOC,TN,TP,AP,NH₄⁺-N,MBC,while had highest soil K,Ca,Mg,DOC.The correlation analysis between soil physicochemical properties showed that there were significant positive correlations between soil NH₄⁺-N and soil SOC,TN,TP,AP,MBC;soil NO₃^--N and soil SOC,TN;soil K and soil Ca,Mg;soil Ca and soil Mg;soil SOC and soil TN,TP,AP,DON,MBC;soil TN and soil TP,AP,DON（p<0.05）.There were significant negative correlations between soil p H and soil DOC,DON;soil NO₃^--N and soil MBN;soil K and soil SOC,MBN;soil Ca and soil SOC,TP,AP,MBC;soil Mg and soil SOC,TP,MBC;soil SOC and soil MBN,soil TN and soil MBN;soil TP and soil DOC;soil DON and soil MBN（p<0.05）.（2）Characterization of leaf nutrients in Torreya plantations with different yields.In different yield stands,foliar Ca,P and chlorophyll a/b were significantly different（p<0.05）.There were no significant differences in foliar C,N,K,Mg,chlorophyll a,chlorophyll b,chlorophyll a+b,and carotenoid content（p>0.05）.Torreya yield had a significant effect on foliar N:P（p<0.05）,and extremely significant effect on foliar C:P（p<0.01）and no significant effect on foliar C:N（p>0.05）.In low yielding forest,the contents of foliar K,Mg,N,P and chlorophyll b were the lowest,while the foliar Ca,C and chlorophyll a/b,as well as the values of C:N,C:P and N:P were the highest.The correlation analysis between leaf nutrients showed that there were significant positive correlations between foliar Mg and chlorophyll a+b;chlorophyll a and chlorophyll b,chlorophyll a+b,carotenoid content;chlorophyll b and chlorophyll a+b,carotenoid content;chlorophyll a+b and carotenoid content（p<0.05）.（3）Correlation analysis between soil and foliar nutrients in Torreya plantations showed that,In the 0-10 cm soil layer,there were significant correlations between foliar C and SOC;foliar P and soil Ca and DOC;foliar Ca and soil p H,TP;foliar Mg and soil EC;foliar N:P and soil P,C:P（p<0.05）.There were extremely significant correlations between foliar Mg and soil MBN;foliar N:P and soil N:P（p<0.01）.In 10-30 cm soil layer,there were significant correlations between leaf N and soil EC;foliar P and soil Ca;foliar Ca and soil NO₃^--N,DON;foliar C and soil N:P（p<0.05）.There were extremely significant correlations between foliar Ca and soil K,Mg（p<0.01）.