Effects Of Water Stress On The One-Year Seedling Growth And Physiology Properties Of Pteroceltis Tatarinowiieroceltis Tatarinowii, Taxodium Distichum And Fraxinus Velutina

This paper had dealt with the study on the one-year seedlings of Pteroceltis tatarinowii, Taxodium distichum and Fraxinus velutina with the pot planting experiments in greenhouse, especially putting emphasis on the study of the P. tatarinowii. The aim was to provide theorial basis for developing P. tatarinowii plantations. Based on the investigation and research of the seedling growth and physiological properties under the five water treatments (treatment Wl: flooding stress, treatment W2: waterlogging stress, treatment W3: control, treatment W4: moderate drought, treatment W5: severe drought), the main conclusions were drawn as follows:1. W1 and W2 treatments accelerated the growth in height, diameter and biomass of T. distichum and F. velutina, especially for T. distichum, while they reduced the growth in height, diameter and biomass of P. tatarinowii. They made P. tatarinowii withered irretrievably after treated for 4 days continuously. W4 and W5 treatments reduced the growth in height, diameter and biomass of T. distichum and F. velutina, and especially for T. distichum. W4 treatment improved the growth of P. tatarinowii, while W5 treatments reduced the growth of it.2. To the five indexes of root vigour, leaf water potential, leaf relative conductivity rates, the activity of SOD and MDA contents, Wl and W2 treatments did fewer effects on T. distichum and F. velutina than drought stresses did; moreover, Wl and W2 treatments did more effects on F. velutina than on T. distichum, while W4 and W5 treatments did more effect on T. distichum than on F. velutina. The effects of the three treatments on P. tatarinowii were in order of W4W5. To T. distichum, they were followed the order of W2>W1>W4>W5. To F. velutina, they were followed the order of W4>W1>W2>W5. According to the theory of Farquhar, it could be concluded that the reduction of stomatal conductance made the decrease of net photosynthesis.4. In response to the five water treatments, the chlorophyll contents of Taxodium distichum and Fraxinus velutina decreased gradually with the prolongation of the time, but there were no close relations between their tolerances to water stresses. The effects of the three water treatments on the chlorophyll contents of P. tatarinowii were significant and could be in order of W4F. velutina>P. tatarinowii; the tolerance to drought of them was in order of P. tatarinowii >F. velutina>T. distichum. From the prospective of growth and paper-making properties, treatment W4 is favorable to P. tatarinowii.