Growth And Stoichiometric Characteristics Of Populus Deltoides And Populus × Canadensis Moench In Five Soil Types

Poplar is widely cultivated in China,a kind of fast-growing tree species with wide adaptability and rapid growth.The cultivated area is over 100 million acres of land,ranking first in the world.Wood is widely used in papermaking,furniture,biofuels and so on.In China,Populus deltoides and P.× canadensis Moench are the most important afforestation species of poplar plantation,and their distribution area in China reaches more than 30 million acres of land.The soil types of these two poplar cultivation areas are mainly red soil,loess soil,yellow-brown soil and purple soil,but there is no relevant research to pay attention to the optimum soil types for the growth of two kinds of poplars.Ecological stoichiometry is based on the basic principles of ecology and chemometrics,and studies the theory and science of the balance of energy and multiple chemical elements in ecosystems.Ecological chemometrics is an important indicator to measure the nutritional balance and nutritional deficiencies of plants.The nutrient demand of poplars often contradicts the supply of soil nutrients,and changes with changes in soil nutrient conditions and growth periods.Poplar C/N,C/P,N/P and other Chemical characteristics will also change.In this study,five soils,red soil,loess soil,yellow-brown soil,acid purple soil and alkaline purple soil,were used as cultivation substrates to study the growth status,photosynthetic rate,stoichiometric characteristics,and nutrient contents of two poplars under different soil environmental conditions.The utilization efficiency will help to screen the suitable soil types of the two poplars,understand the relationship between soil nutrient supply and soil stoichiometric characteristics,and clarify the intrinsic link between the organ stoichiometry of poplars and the nutrient use efficiency and nutrient deficiencies of plants.The main results are as follows:(1)P.× canadensis Moench grows well in the two purple soil environments,has higher biomass,and grows worst under loess soil conditions.P.deltoides grows well in yellow-brown soil and acid purple soil,biomass is also large,loess soil conditions are the worst,and biomass is also the lowest.(2)The net photosynthetic rate(Pn)of P.× canadensis Moench under acidic purple soil was the largest,and Pn under yellow-brown soil was the minimum.Under red soil conditions,the Pn of P.deltoides was the largest,and the Pn under acidic purple soil was the smallest.The relationship of stomatal conductance Gs,transpiration rate and net photosynthetic rate of two poplars in different soil types were similar.Under the acidic purple soil condition,Ci of the P.× canadensis Moench was the largest,while in the five soil conditions,there was no significant difference in the Ci of P.deltoides.(3)Among five different soil types,the efficiency of photosynthetic nitrogen use was higher in P.× canadensis Moench when grown in yellow soil and red soils,while there was no significant difference in photosynthetic nitrogen use efficiency in different soil conditions of P.deltoides.Under acidic purple soil conditions,the photosynthetic P use efficiency of P.deltoides was the highest,that of yellow-brown was the lowest,and that of P.deltoides was the highest under red soil conditions,and that of Yellow soil was the lowest under yellow-brown soil conditions.(4)The C content of P.deltoides under loess soil conditions was low,but there was no significant difference in the other soil conditions.There was no significant difference in C content of P.deltoides under various soil types.The contents of N in P.× canadensis Moench were in acid purple soil > basic purple soil > yellow-brown soil > red soil > loess soil.The contents of N in P.deltoides leaves were loess soil > red soil > yellow-brown soil > acid purple soil = basic purple soil.The P contents of the leaves of P.× canadensis Moench were in the sequence of basic purple soil > acid purple soil> yellow-brown soil> red soil>loess soil.The P contents of the leaves of P.× canadensis Moench were yellow-brown soil > loess soil > red soil> basic purple soil> acid purple soil.The C/N of P.× canadensis Moench leaves were loess soil > red soil > yellow-brown soil > basic purple soil > acid purple soil.The C/N of P.deltoides leaves were alkaline purple soil > acid purple soil> red soil= loess soil= yellow-brown soil;There was no significant difference in C/P of P.× canadensis Moench leaves under various soil types.The C/P of P.deltoides leaves under yellow-brown soil conditions was significantly lower than that of other soils;the N/P of P.× canadensis Moench leaves were acid purple soils in that order.Yellow-brown soil > alkaline purple soil > red soil > loess soil,N/P of P.deltoides leaves were loess soil > red soil > acid purple soil > alkaline purple soil > yellow-brown soil.(5)The N use efficiency of P.× canadensis Moench under the conditions of each soil type was alkaline purple soil > red soil > loess soil = acid purple soil > yellow brown soil,and P use efficiency was acid purple soil > basic purple soil > loess soil > red soil > yellow-brown soil;N use efficiency of P.deltoides in the order of alkaline purple soil > acid purple soil > red soil > yellow-brown soil > loess soil,N use efficiency was acid purple soil > alkaline purple Soil > red soil > loess soil > yellow-brown soil.P.deltoides and P.× canadensis Moench had higher N and P use efficiency in the two purple soils,and N and P use efficiency was lower in red soil and loess soil.P.× canadensis Moench grow best under the nutrient supply conditions of two purple soils.Populus deltoides grows best under the nutrient supply conditions of yellow-brown soil and acid purple soil.Two kinds of poplars in the study under the conditions of soil nutrient supply,growth is mainly limited by N.