Comparative study on photosynthetic characteristics of different Catalpa bungei clones

Measurements of photosynthetic characteristics of 5 Catalpa bungei clones (1-3，1-4，004-1，015-1 and 7080) by Li-6400 portable photosynthesis system were indicated that，(1) Light response curves of 5 clones were roughly the same, the maximum net photosynthetic rate (Pmax) was ranked as follows: 1 -3 >7080 >015 -1 >004 -1 >1 -4. Clone 1 -3 and clone 7080 had strong light environmental adaptability, the light saturation point(LSP) of them were 1 147.97 μmol/m2.s and 1 196.31 μmol/m2.srespectively , and clone 1-4 had narrowest range of adaptation to light. (2) Total photosynthetic amount per area of 5 clones were quite different, clone 1-4 was the best(433 974.24 μmol/m2) , and clone 1-3 was the second(401 290.20 μmol/m2). (3)Five clones'trends of tanspiration rate(Tr) were the same as stomatal conductance (Cond), the diurnal variation curves of net photosynthetic rate (Pn) of clone 1-3, 1-4 and 015-1 showed two typical peaks with obvious midday depression, but clone 004-1 and 7080 didn't. (4) Considering a variety of photosynthetic characteristics indicators, photosynthetic capacity of clone 1-3 was the best among 5 Catalpa bungei clones.