The Study Of Foliar Functional Traits And Nutrient Resorption In Aleurites Montana Provenances

As a deciduous arbor belonging to euphorbiaceae,Aleurites montana is fast-growing,strong pathogen resistant and well adapted to the site.Aleurites montana is also a multi-functional tree species with high economic and ecological values,which can be applied as plantations for timber,industrial raw material,energy and ecological restoration.Therefore,the tree species has been widely planted in southern regions,especially in northern part of Fujian Province.In the thesis,Aleurites montana of Jianyang,Youxi,Shaxian,Putian and Zhenghe provenances planted in the same area were studied to compare provenance differences in foliar structural traits,construction cost,photosynthetic and chlorophyll fluorescence characteristics,nutrient contents in mature and senescent leaves and foliar nutrient resorption efficiency.The adaptation of Aleurites montana provenances to poor site conditions in northern hilly regions of Fujian Province was examined in the aspects of foliar functional traits and nutrient resorption efficiency to select favorable provenances with high nutrient efficiency.The main results were listed as below.1.In foliar structural traits,there were significant differences in leaf dry matter content,specific leaf area,leaf thickness,leaf volume and leaf tissue density among various Aleurites montana provenances.JY provenance was capable of maintaining nutrient gain with highest leaf dry matter content and leaf tissue density,and lowest specific leaf area.PT provenance had higher water absorption efficiency with smallest leaf index,large specific leaf area,thick leaves and low leaf tissue density.Generally speaking,there were no obvious differences in leaf index among provenances,probably due to the roles environmental factors played.Leaf dry matter content was in significant negative correlation with specific leaf area while in positive correlation with leaf tissue density,and specific leaf area was in significant negative correlation with leaf thickness.There were trade-offs among foliar structural traits of Aleurites montana provenances.2.In different Aleurites montana provenances,the mass-based leaf construction cost was from 1.477 to 1.525 g glucose/g,the area-based leaf construction cost was from 103.471 to 134.471 g glucose/m2 and foliar cost benefit ratio was from 20.317 to 29.489 g s/μmol.There were obvious provenance differences in ash content,area-based leaf construction cost and foliar cost benefit ratio,which indicated the genetic variation in foliar construction.JY and ZH provenances had higher nutrient accumulation capacity with high ash contents.SX and PT provenances had competitive advantages with less investment in leaf construction.The foliar cost benefit ratio was in the order of JY>SX>ZH>PT>YX,among which JY and SX invested more energy into defense strategy for better resistance against adverse environments while YX and PT invested more energy into photosynthetic organs for fast growth.The mass-based leaf construction cost was effected by ash content and calorie value while the area-based leaf construction cost was in close correlation with ash content,foliar C content and specific leaf area.3.There were significant differences in photosynthetic and chlorophyll fluorescent parameters among Aleurites montana provenances.YX and PT had higher net photosynthetic rates and water use efficiency while ZH,YX and PT had higher chlorophyll fluorescent values.These provenances could be selected and applied as photosynthetic efficient and drought resistant species.The net photosynthetic rate of Aleurites montana increased with the decrease of intercellular carbon dioxide concentration,which indicated that it was effected by mesophyll cell assimilation.Aleurites montana increased its water use efficiency by lowering its transpiration rate.4.There were differences in foliar nutrient contents and nutrient resorption efficiency of upper and lower canopies among Aleurites montana provenances,indicating the effect of canopy microenvironment on nutrient gain and efficiency.The nutrient contents of N,P,K,Ca and Mg in senescent leaves were much lower than those in healthy mature leaves.During fast growing periods,there were high N contents in mature leaves of ZH and PT provenances,high K contents of ZH and JY provenances,high Ca contents in JY provenance and high Mg contents in JY and SX provenances.There were no differences in P contents among various Aleurites montana provenances.In the late growing periods,there were high N and P contents in senescent leaves of SX and YX provenances and high K,Ca and Mg contents in JY provenance.5.Among various Aleurites montana provenances,the foliar N resorption rate was 41.706%,P was 37.728%,K was 50.679%,Ca was 17.149%and Mg was 46.974%.ZH,JY and PT had higher N resorption rate;JY had higher P resorption rate;ZH and PT had higher K resorption rate;and SX,ZH and SX had higher Ca resorption rate.JY and PT had higher Mg resorption rate.Since Aleurites montana provenances adopted various nutrient absorption and utilization strategies,the environmental factors such as soils and climates should be taken into account for the practice of provenance selection and application.