Study On The Adaptability Of Carya Illinoinensis Introduction In Shenyang Area

In this paper,the phenological period,growth,photosynthetic characteristics,drought resistance and cold resistance of Carya illinoensis in Shenyang area were observed and studied.By compared with Juglans mandshurica,analysis the Carya illinoensis introduction adaptability in shenyang,the aim is to provide scientific basis for the introduction,cultivation and domestication of Carya illinoensisin high latitudes of China.The main findings are as follows:（1）Carya illinoensis in shenyang area were germinated in late April,entered leaf-developing stage in early may,flowering in early may began,and new branches began at the same time.The fruit ripened in late September and entered the deciduous stage in late October,with an annual growth season of 195d.Compared with the experimental comparison materials,the stage in germination were later,the growth period were shorter,and the fruit kernel rate were lower.However,the male and female inflorescences and the length of annual branches are same as those of other suitable areas in China,and can grow normally.（2）The net photosynthetic rate of Carya illinoensis in Shenyang area showed the double-peak curve in June,July and September,and there was an obvious"photosynthetic lunch break"phenomenon,the peak value at 10 am and 4 pm.The trends of transpiration rate and stomatal conductance were approximately the same as the net photosynthetic rate,the intercellular CO₂concentration showed inverted U curve with high morning and evening and low noon.The net photosynthetic rate,transpiration rate and stomatal conductance of the experimental tree species in July were all higher than that in June and September.（3）The relative water content and chlorophyll content in the leaves of Carya illinoensis were lower than Juglans mandshurica,and the water retention ability of the leaves was relatively weak,with extremely significant difference between the two.At the same time,Juglans mandshurica have more palisade tissues than Carya illinoensis,and The thickness ratio of palisade tissues to sponge tissues,cuticle thickness,upper epidermis thickness and lower epidermis thickness of Juglans mandshurica were higher than Carya illinoensis.（4）Carya illinoensis in Shenyang have thicker xylem,higher xylem ratio and ratio of xylem to cortex.Under the low temperature stress,the electrical conductivity of Carya illinoensis and Juglans mandshurica rised in an S-shaped curve,and the LT₅₀of Carya illinoensis was-38.93℃,which is lower than-34.46℃ for Juglans mandshurica.the soluble protein conten、malondialdehyde content and SOD、POD activity of both showed a trend of increasing first and then decreasing with the decrease of temperature,and the soluble sugar content increased with the decrease of temperature.The ratio of xylem of the two tree species is significantly negatively correlated with LT_50.Principal component analysis and correlation analysis were carried out for each physiological index show that the adult Carya illinoensis have strong cold resistance and can overwinter normally in Shenyang area.（5）Studies on phenology and growth characteristics,photosynthetic characteristics and stress resistance of Carya illinoensis show that the introduction of Carya illinoensis in Shenyang area has good adaptability.