Response Of Compound Leaf Functional Traits Of Male And Female Fraxinus Mandshurica To Different Habitats

Leaf can adapt to environmental changes through morphological and structural changes.It is not only an important organ to ensure the survival of plants in the changing environment,but also an important phenotypic index to measure plant stress tolerance.Compared with simple leaf,compound leaf has two advantages of promoting the rapid growth of trees and adapting to seasonal drought.The response of leaf functional traits of dioecious plants with compound leaf in different habitats can be used as an important feature to fully understand the heterogeneous habitat suitability mechanism of dioecious plants.Fraxinus mandshurica is a typical dioecious tree and one of the precious timber trees in Northeast China.This study took compound leaf of male and female plants of Manchurian ash mature plantation in the drought saline-alkali habitat and suitable habitats as the research material.The differences of morphology,structure,photosynthetic function and stoichiometric ratio of compound leaf and leaflets were analyzed under the action of gender and habitat.The study found:(1)In the suitable habitat,the peoportion of compound leaves with 9 leaflets and 11 leaflet of male plants accounted for about 40%,and the compound leaf of Fraxinus mandshurica female plants was mainly 11 leaflets,accounting for 70%.In the drought salinealkali habitat,the compound leaf of male and female plants was mainly 9 leaflets,accounting for 75%.(2)In drought saline-alkali habitat,the leaf area and leaf water content of three types compound leaf of the male and female plants and the photosynthetic capacity of compound leaves with 9 leaflets and 11 leaflets decreased significantly.At the same time,the dry matter content of compound leaf and the thickness of epidermal cells,palisade tissue and sponge tissue of compound leaf increased significantly,but the morphology and photosynthetic capacity of compound leaf with the same number of leaflets of female and male of Fraxinus mandshurica did not show gender differences.In drought saline-alkali habitat,the net photosynthetic rate of compound leaf with 9 leaflsts of the female plants decreased by 31.02%and compound leaf with 9 leaflets of the male plants decreased by 20.04%,the decrement of net photosynthetic rate of the female plants was higher than that the male plants.(3)In the suitable habitat,the specific leaf area,the leaf area,leaf dry weight and the thickness of palisade tissue and spongy tissue of the compound leaf with 11 leaflets of the female and male plants was significantly higher than the compound leaves of 7 and 9 leaflets.In drought saline-alkali habitat,although the specific leaf area of compound leaf with 9 leaflets of the male and female plants was smaller than the compound leaf of 11 leaflets,the leaf dry matter content and spongy tissue thickness of compound leaf with 9 leaflets of the male plants were significantly higher than the compound leaf with 11 leaflets.At the same time,the net photosynthetic rates of compound leaf of the 9 and 11 leaflets of the male was significantly higher than the compound leaf of 7 leaflets in the two habitats,while the net photosynthetic rates of compound leaf of the three types of the female were not significantly different.(4)In drought and saline-alkali habitat,the leaf area of the lateral leaflets of the upper two pairs and the terminal leaflet decreased significantly,while the reduction of leaf area was mainly caused by the reduction of leaf length.Compared with the suitable habitat,there was no significant difference in stomatal density between different leaflets of the male and female plants in drought and saline-alkali habitat.As the same time,the thickness of epidermal cells,palisade tissue and spongy tissue between different leaflets were significantly different,showing different anatomical structural characters.The total carbon content of terminal leaflets of the female was significantly higher than that of other leaflets rank,but there was no significant difference in total nitrogen and total phosphorus content between the male and female plants.(5)The plasticity index of leaf dry weight,thickness of palisade tissue,thickness of sponge tissue,total nitrogen and total phosphorus of 9 leaflets compound leaf was higher than the 11 leaflets compound leaf.At the same time,the dry weight,thickness of palisade tissue,thickness of sponge tissue,total nitrogen and total phosphorus of leaflets were higher than the plasticity index of leaflets morphology.In conclusion,the compound leaf with different number of leaflets of male and female Fraxinus mandshurica have different manifestations in different habitats.In drought and saline-alkali habitat,the 9 leaflets compound leaf of male and female Manchurian ash were the most important leaf formation response units,because they had a higher proportion of numbers,higher net photosynthetic rate,higher leaf dry weight,thicker leaf tissue and smaller leaf length.In suitable habitat,the 11 leaflets compound leaf of male and female Manchurian ash were the most important leaf formation response units,because they had a higher number proportion,higher leaf area,higher leaf dry weight,and thicker leaf tissue.At the same time,the leaflets of different leaf rank of male and female Manchurian ash mainly responded to the drought and saline-alkali habitat by adjusting the thickness of leaf anatomy,among which the terminal leaflet and the upper first pair of lateral leaflets had higher tolerance.