Study Of Photo Synthetic Characteristics Of Betula Luminifera Breeding Resources

As global warming, I research the adaptability of Betula luminifera species to climate change andput forward the high light efficiency breeding strategy of Betula luminifera. Using different provenance,family, clone Betula luminifera as breeding material, I lay out my research in the aspects of branching,leaf and photosynthetic characteristics. In the research I choose net photosynthetic rate as main indicatorto filter out the high photosynthetic efficiency of Betula luminifera species. At the same time, I explorehigh light efficiency breeding strategies to support high photosynthetic efficiency breeding research. Myresearch results as follow:(1)The diurnal variation of Betula luminifera net photosynthetic rate (Pn) presents single peak anddouble peak mode. Double peak curve has the phenomenon of photosynthetic "noontime rest". Thevariances of light saturation point of the three2clones are from1342.8to1609.0μmol m-2s-1,Lightcompensation point from18.1to27.2μmol m-s^-1. The variances of CO2saturation are from2000to2350.0umol mol^-1, CO2compensation point from61.5to76.7μmol mol-1.The various clones' strengthof photosynthetic midday depression is different and each photosynthetic indicator show a greaterdifference that providing the rich breeding resources for the high light efficiency Betula luminiferbreeding.(2)By studying the photosynthetic characteristics of various sources, I find they have differentphotosynthetic capacity at different stages. Through studying the net photosynthetic rate of five sourceBetula luminifera according latitude, elevation and the average annual temperature of species, we findthe net photosynthetic rate has positive correlation with latitude in spring, summer and autumn; the netphotosynthetic rate no obvious correlation with the mean annual temperature; the net photosyntheticrate decreased with altitude increasing, showing negative correlation. That mean the net photosyntheticrate of different provenances Betula luminifera in north and south is affect by genetic, environmentaland other factors; net photosynthetic rate of different provenances are not sensitive to temperaturechanges, but in continuous high temperature conditions the different provenances have great differencein photosynthetic rate. Therefore, Betula luminifera has a good potential ability in response to climatechange and pertinent high light efficiency breeding at the level of Betula luminifera species plays a keyrole.(3)By studying photosynthetic yield (main consideration factor), branch spacing and branch anglefactors, I select67,55,54,58,1,56,14clones Betula luminifer high light efficiency species as newspecies.67clone belongs to the Anhui Mount Huangshan provenances55familys;55,54and58,56clones belong to Guizhou Xiuwen provenances45,47predigrees respectively;1clone belongs to theZhejiang Ling'an source1familys;14clone belongs to the Sichuan Qionglai provenances17familys.