The Research On The Photosynthesis And Water Eco-physiological Characteristics Of Pinus Tabulaeformis Carr. And Picea Meyeri Rehd.et Wils

The photosynthesis and water eco-physiological characteristics of Pinus tabulaeformis Carr. aged 16 and Picea meyeri Rehd. et Wils. aged 14 under different water deficit were studied in Huhhot suburb in semi-drought areas. The research indicated , (1)The resaturate relative water content (RSRWC )of the trees tested declined as their water deficit increased .When the water deficit increased to the water condition at the initial loss point of the turgor ,RSRWC was about equal to 1. It showed the trees were not damaged in the condition of the initial losing rurgor in the short period and had the capability of maintaining the life characteristics of the absorbing water completely etc. . (2) The relative total photosynthesis rate of the trees above inclined With the increasing of their water deficit .The water potential absolute value( ψPH) that the relative total photosynthesis, rate equaled to 0 differed in the different growth period. ψPH is the minimum in the thrive growth period. The trees had the minimum of ψPH in the thrive growth period ,which of Picea meyeri and Pinus tabulaeformis was 3.37 and 3.94 Mpa separately . ψPH was the critical potential value of trees life stopping initially and the parameter of evaluating the adaptability of trees to the drought environment . (3) The result of comparing ψPH, ψbw, ψpw and πp in the thrive growth period, showed that ψbw was the greatest , ψPH and ψpw were less and similar, and πp was the least .It was a characteristic of trees that ψPH, ψpw and π p were greater and the adaptability of trees to the drought environment was stronger .According to it finus tabulaeformis had greater ψPH and ψpw and stronger resistance to drought environment than Picea meyeri in the thrive growth period . (4) The growth water potential field (GWPF) and the life water potential field (LWPF) of trees had the characteristic which changed with different growth period .They were the narrower in the growth period but were wider in the ripe growth period. In the thrive growth period ,GWPF and LWPF of Picea meyeri were 0.67 and 2.88Mpa, those of Pinus tabulaeformis were 0.70 and 3.19Mpa. Applying GWPF and LWPF in the thrive growth period to the parameter of evaluating adaptability of trees to the drought environment, Pinus tabulaeformis had greater of GWPF and LWPF and stronger adaptability than Picea meyeri. The result was accordant with that of evaluating trees using ψpH and ψpw.