Study On Photosynthetic Characteristics Of Three Cultivars Of Hybrid Cymbidium During Three Flowering Stages

In this paper,the experimental materials which named Hybrid Cymbidium was determined by LI-6400 during early blooming stage,full blooming stage and blooming last stage of Hongxia,Golden age and Gold Jasmine respectively. We determined the photosynthetic characteristics,the response of Pn to elevate CO₂ concentration and photosynthetic active radiation and the characteristics of chlorophyll fluorescence parameters.We also analyzed the levels of chlorophyll, soluble sugar content,soluble protein content and the activities of POD,SOD of leaves.Analyzed and compared the photosynthetic physiological characteristics and regular pattern of Hybrid Cymbidium leaves during three flowering stages.The conclusions were:1.Photosynthetic characteristics of the same specie in three blooming stages had differences.The responsive value of Pn to elevate CO₂ in early blooming stage was higher than full blooming stage and blooming last stage.The AQY was the highest in the full blooming stage.The order of CCP of Hongxia and Golden age was:full blooming stage＞blooming last stage＞early blooming stage, but Gold Jasmine was blooming last stage＞full blooming stage＞early blooming stage.The response value of Pn-PAR in early blooming stage was the biggest and in blooming last stage was the smallest.The order of LCP of Gold Jasmine and Golden age were:blooming last stage＞early blooming stage＞full blooming stage and the Hongxia was blooming last stage＞full blooming stage＞early blooming stage.The AQY of Hongxia and Gold Jasmine were the highest during early blooming stage,Golden age was the smallest.Fo of Gold Jasmine and Golden age were:blooming last stage＞full blooming stage＞early blooming stage.And Golden age was the biggest during early blooming stage.The order of Fm was:blooming last stage＞full blooming stage＞early blooming stage.The Fv/Fo,Fv/Fm had the same trend of the Fo. The NPQ and qP were the biggest and theΦ_PSâ…¡ was the smallest during blooming last stage.The contents of chlorophyll a of blooming last stage and the chlorophyll b of early blooming stage were the lowest,the order of chlorophyll(a/b) and the content of carotenoid was:early blooming stage＞full blooming stage＞blooming last stage.The content of chlorophyll(a+b) had differences.The order of the soluble sugar content was:early blooming stage＞full blooming stage＞blooming last stage and the content of full blooming stage was obviously higher than other stages.The order of the activity of POD was:early blooming stage＜full blooming stage＜blooming last stage.2.During the same stage,the order of the responsive value of Pn to elevate CO₂ of all species was:Gold Jasmine＞Hongxia＞Golden age.The CCP of Golden age was the highest and Gold Jasmine was the lowest.The CE of Gold Jasmine was the highest.The response value of Pn-PAR of Hybrid Cymbidium leaves had differences,and Gold Jasmine＞Hongxia＞Golden age.The light saturation points of three species were similar;The light compensation point of Gold Jasmine was the smallest.The AQY of Gold Jasmine was the biggest.The Fo of Gold Jasmine was the biggest.The Fo of three species had no significant differences.The Fv/Fo and Fv/Fm of different kinds of Hybrid Cymbidium had some differences.The NPQ of three species had no significant differences during early blooming stage and full blooming stage,and Golden age was higher than Gold Jasmine and Hongxia during blooming last stage.Φ_PSâ…¡ no significant differences in three species during early blooming stage and full blooming stage.Gold Jasmine and Hongxia had significant differences compared with Golden age during blooming last stage.The content of chla,chlb and chl(a+b) of Gold Jasmine were the lowest, but the content of carotenoid and chl(a/b) had differences.The soluble sugar content of Hongxia during early blooming stage was the lowest,after that,three species were no significant differences.The soluble protein content of three species during the same stages had no significant differences.The activity of POD had significant differences between different species.The activity of SOD had no regular change.3.The curve of Pn diurnal variation presented typical double-peak curve, and there is obvious "midday depress" phenomenon.The peak values occurred at about 11:00 and 15:00 respectively.The second peak value was lower than the first one.The trend of three blooming stages was the same.To sum up,the effective way to improve the photosynthetic rate of Hybrid Cymbidium was increased CO₂ concentration.PAR between 800 and 1000μmol·m^-2·s^-1 benefited their growth.The fluorescence characteristics and physiological indicators were different during different species and different flowering stages.That could provide a theoretical basis for production management of Hybrid Cymbidium.