Research On Photosynthesis Characteristics Of Phoebe Bournei Young Plantation

The physiological and ecological factors of net photosynthetic ratio (Pn) and transpiration rate (Tr) of Phoebe bournei young plantation was measured in Jindong District, Yongzhou City, Hunan Province by using LI-6400portable photosynthetic machine, while the light response curve was measured. The study focused on daily variance, seasonal variance, location difference and light response of/to photosynthetic ratio and transpiration rate to put forward the scientific basis of cultivation techniques, introduction and its development and processing.The results were as follows:(1)The daily Pn variances of upper and lower leaves were mostly single peak curve and also double peak curve. The peak times of single one and double one were different. The peak times were different even for the same type of curves, or Pn were different as same peak time, and the higher peak value showed at10:00-12:00. The seasonal Pn variance of upper and lower leaves were single peak curve which highest values (4.65[μmol·m-2·s-1,3.55μmol·m-2·s-1) were in September. There was no regulation of the Pn in different months in four locations (east, south, west and north) of upper and lower leaves. The decreased order of Pn in the whole young tress (the averaged value of upper and lower position) was west, south, north and east.(2)The daily Tr variance of upper and lower leaves of young Phoebe bournei showed single peak and double peak, most of which was single one just like that of Pn. The max Tr of upper leaves in July was6.09mmol·m-2·s-1which was higher than5.00mmol·m-2·s-1, which means it was belong to light transpiration type. The seasonal Tr variance was single peak which top was in July. There was no regulation of four locations in different months. The decreased order of Tr for the whole young tree was west, south, north and east, and the distances between closed ones were little.(3)The daily WUE variance of upper and lower leaves were single peak, double peak and tri-peak. The peak times of the same curve or varied peak showed no regulation with different highest peak values. The seasonal WUE variance was double peak which top was in September. There was no obvious regulation of four locations in different months. The decreased order of WUE for the whole young tree was south, west, north and east.(4)The Pn increased with the increased of PAR.;Tr and PAR were direct proportion (photosynthetic active radiation was50μmol·m-2·s-1);Ci and PAR were proportional in April; The Cond increased with the increased of PAR (photosynthetic active radiation was50μmol·m-2·s-1);In September WUE and PAR were direct proportion.