| The Picea species are of great economic and ecological values.Previous studies focus little on needle morphological and anatomical traits and wood anatomical traits of multiple Picea species.Although some studies have shown that the species introduced from abroad grow better than the native species in the introduction sites,few studies have tried to explain the growth differences among species from the perspective of photosynthetic characteristics.And there has been no report on the difference in nitrogen allocation in the photosynthetic system of multiple Picea species.Therefore,this study selected P.glauca,P.mariana introduced from Canada and domestic P.crassfolia,P.likiangensis,and P.koraiensis as materials to explore the differences in needle and wood traits among different Picea species and furtherly reveal the differences in photosynthetic physiological characteristics and nitrogen allocation in the photosynthetic system of Picea species.Moreover,the instrinsic relationship among growth,photosynthetic characteristics,wood anatomical traits,needle structure and physiological traits were studied.The main findings of this study were:1.Needle morphology and anatomy varies tremendously among species.Different degrees of variation were found in needle traits among species.Correlation analysis showed that: the area of needle cross section,mesophyll,epidermis and central cylinder were significantly positively correlated with each other.The area of needle cross section,mesophyll and epidermis increased,while the fraction of central cylinder and resin canals decreased with needle length.2.Part of wood anatomical traits varied significant among species,such as ring width,late wood width,and the length of fibers in early and late wood.It showed a significantly positive correlation between ring width and late wood width and between the length of fibers in early and late wood.The correlations between wood anatomical traits and needle morphology and anatomy may be related to functions such as photosynthetic carbon assimilation.3.Significant differences were observed in growth traits among species.P.glauca had the best growth performance.Its tree height(3.03m),diameter at breast height(3.63cm),and number of first lateral branches(90.19)were the largest among the five species,while P.crassfolia had the worst growth performance.In addition,the number of first lateral branches was significantly positively correlated with height and diameter at breast height.4.The photosynthetic characteristics varied significantly among species.P.glauca had the largest photosynthetic rate and water use efficiency,while the two traits of P.crassfolia were the smallest among species.The fraction of needle nitrogen allocated to Rubisco(PC)were larger than that allocated to bioenergetics(PB)and light-harvesting components(PL)in five species.The fraction of needle nitrogen allocated to photosynthetic system of P.glauca and P.mariana were the largest among the five tested species,49.18% and 41.63% respectively,while the fraction of P.koraiensis was the smallest(14.20%).In addition,P.glauca had the largest photosynthetic nitrogen use efficiency(93.46?mol·mol-1·s-1)among species while P.koraiensis and P.crassfolia had the smallest(26.16 and 26.64?mol·mol-1·s-1,respectively).5.The differences in growth characteristics among species were related to differences in photosynthetic capacities and photosynthetic nitrogen use efficiency.The best growth performance of P.glauca might be attributed to its maximum photosynthesis rate,water use efficiency and photosynthetic nitrogen use efficiency among the five tested Picea species.In addition,variations in photosynthetic capacity and photosynthetic nitrogen utilization efficiency have a significant impact on the formation of wood anatomical traits in Picea species.Variations in photosynthetic rate were related to stomatal density,stomatal conductance,mesophyll conductance,and the content of chlorophyll a.These four indicators were significantly positively correlated with photosynthetic rate. |
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