Study On Photosynthetic Traits Of Catalpa Bungei With Different Cultivation Patterns

This study analysed the relationships between factors and rates based on photosynthetictraits，factors including environment factor, cultivation factor and species mass factor，ratesincluding net light collection rate and transpiration rate. catalpa bungei from the Wei Riverexperimental station of Northwest A&F University were chosen as research objects. Li-6400portable light collection analysis system was used in this research. Results of this studyindicated：(1) During June to September, daily variation type of net photosynthetic rate of differentcultivation modes of catalpa bungei were mostly double peaks. Furtherly, for high-forest andleaved forest, the first peak> second peak. Photosynthesis of different cultivation modes ofcatalpa bungei presented obvious "lunch break" phenomenon.(2) Research on the relationship between net photosynthetic rate and environmentalfactors of different cultivation modes of catalpa bungei showed: For high-forest, the mainfactor of Pn was Tr in June， Gs in July and August, and PAR in September. Relatively, forleaved forest, the main factor of Pn was Tr in June, and Gs in July to September.(3) The daily variation curve of transpiration rate of different cultivation modes weregenerally consistent with the net photosynthetic rate in June to September, presenting bimodalpattern curve. From the daily variation process of transpiration rate, the value of Tr ofhigh-forest was generally larger than leaved forest. In the leaf level, water consumption ofleaved forest was less than high-forest, showing bigger capacity of water-saving.(4) Monthly variation of daily assimilation volume of different cultivation modes ofcatalpa bungei were: High-forest, July> June> August> September. Leaved forest, July>August> June> September. From the view of daily transpiration volume，leaves forest waslower between June to August, while high-forest, high efficiency in transpiration, always hadlarger daily assimilation volume and higher transpiration efficiency. That means, high-forestwas obviously better in growth than leaved forest，by comparing two different cultivationmodes of catalpa bungei.(5) Daily change rule of two different cultivation modes of catalpa bungei were generallysimilar on Gs and Tr, both presenting generally bimodal curve. Monthly variation of stomatalconductance of high-forest was: July> June> August> in September. While monthly variation of stomatal conductance of leaved forest was: July> August> June> in September.Daily variation curves of intercellular CO2concentration mostly showed "u" type. Besides, Cihas a direct impact on Pn. During June to September， daily variation process ofphotosynthetically active radiation (PAR) presented unimodal curve, as well as airtemperature (Ta) and leaf water vapor pressure difference (Vpdl), and air relative humidity(RH) daily variation curve was u-shaped.(6)By analysing of different cultivation patterns of light response curves of catalpabungei, came the conclusion: High forest, low of LCP but high of LSP，was available of widerange of light and had strong adaptability to light environment. Comparing, leaved forestcould use shorter range of light and was weaker in the adaptability to light environment.However, leaved forest was stronger in respiratory than high-forest, for the later had lower Rdvalue.Hope results of this study could help to provide a basis study and exploratory data onhigh quality and high yield management of catalpa bungei.