Comparison On Growth And Photosynthetic Characteristics Of Poplar Clone ’L35’ And ’I-107’ Plantation

Populus×euramericana ‘L35’ is the most excellent poplar clones which was bred in recent years, and I-107 is the main poplar clones of poplar in Shandong province. The growth and photosynthetic property of 6-year-old poplar clone ‘L35’ was systematically studied using poplar clone ‘I-107’ as control. The results showed that:(1) The growth. The growth amount of tree height, DBH, crown diameter, tree volume growth were measured item by item and found that 6-year-old poplar clone ‘L35’ is better than the current main cultivated poplar clone ‘I-107’,and poplar clone ‘L35’ is suitable for growing in the area.(2) Growth rhythm. 6-year poplar clones ‘L35’ and ‘I-107’are still in rapid growth period. Poplar clone ‘I-107’dramatic increased in tree height in the first third year, then the rate of increase slowed, while poplar clone ‘L35’was always at increased stage, showing strong growth momentum. The growth trend in DBH of the two are generally same, in the first three years, Poplar clone ‘I-107’ grew faster, from then on Poplar clone ‘L35’continued to maintain a leading. Cumulative volume increment exhibit similar regularity with that of DBH. The form factor of the two clones showed differences in different years, but keep consistent in the sixth year and they showed good stem form characteristics.(3) Comparison of photosynthetic characteristics. studies have shown that Pmax and LSP of the two species were both higher no matter it is under a weak or a strong light intensity conditions, both of the species shown strong photosynthetic capacity.By comparing, photosynthetic rate Poplar clone ‘L35’ of is higher than Poplar clone ‘I-107’;Transpirationrate of Poplar clone ‘L35’ and ‘I-107’ showed a similar trend, but Poplar clone‘L35’ is always less than Poplar clone ‘I-107’. Moreover, studies about stomatal conductance and light intensity showed that stomatal conductance increases with the enhancement of light intensity, when light intensity below 500 μmol.m-2.s-1, after the light intensity over 500μmol.m-2.s-1, the trend is similar to the transpiration rate and light response curve. Poplar clone‘L35’ net photosynthetic rate is higher than Poplar clone ‘I-107’ and transpiration rate is lower than Poplar clone ‘I-107’. Higher light energy efficiency is the physiological basis of Poplar clone‘L35’ high productivity.Because of the characteristics of fast-growing, smaller branches and much dense and uniform distribution, small crown, straight stem and small taperingness, Poplar clone‘L35’ is suitable for large-scale cultivation in Shandong Province, is an preferred alternative species to Poplar clone ‘I-107’or other clones for afforestation.