Comparative Analysis Of Photosynthetic Characteristics And Mineral Elements In 5 Camellia Oleifera Changlin Series Superior Clones

In this paper,LI-6400 portable photosynthetic instrument was used to determine the photosynthetic parameters of 4,40,27,53 and 3 Camellia oleifera Changlin series superior clones of trees aged 8 years.We measured the Photosynthetic Diurnal Variation of 5 clones in mid August and early November.And then,We analyzed the effects of physiological and ecological factors on net photosynthetic rate by stepwise regression analysis.Photosynthetic parameters such as light compensation point and CO2 compensation point were calculated by fitting photosynthetic-photosynthetic response curve and CO2 response curve.We sampled and measured the contents of photosynthetic pigments and four mineral elements of nitrogen,phosphorus,potassium and magnesium in the leaves of each clone,and investigated tree,leaf and fruit traits,analyzing its correlation with net photosynthetic rate.The purpose of the paper is to provide theoretical basis for breeding and identification of fine varieties and high yield and quality cultivation.The main results are as follows:(1)The diurnal variation curves of net photosynthetic rate of 5 Changlin series superior clones showe that there are two types of "single peak" and "double peaks" in August,only "single peak" in November.In August,the daily average value of Pn of Changlin No.4 is the highest,which is 8.28 μmol.m-2s-1.In November,the daily average value of Pn of Changlin No.53 is the highest,which is 9.31 μgmol·m-2s-1.The 5 clones have significant difference in Pn day average values in August and November,but there is no significant difference in Gs,Ci and Tr.The average Pn days of all clones in November are higher than those in August,and the difference is significant.(2)Significant differences are found in light compensation point,light saturation point,dark respiration rate and maximum net photosynthetic rate among the five clones.The light compensation point is 27.8～50.0 μmol·m-2s-1，the number of Changlin No.40 is the lowest,and Chang Lin No.27 is the highest.The light saturation point is 857.3～1389.3 mol-m-2s.-1 the number of Chang Lin No.40 is the lowest,and Chang Lin No.53 is the highest.Dark respiration rate is 1.62-2.28μmol·m-2s-1,Chang Lin No.40 is the lowest,and Chang Lin No.3 is the highest.The maximum net photosynthetic rate is 10.49-12.72 μmol-m-2s-1,and Chang Lin No.40 is the lowest,and Chang Lin No.53 is the highest.(3)There are significant differences in CO2 compensation point,CO2 saturation point,maximum net photosynthetic rate,carboxylation efficiency and photorespiration rate among the five clones.The compensation point of CO2 is 80-140μmol-mol-1,Changlin No.40 is the lowest,Changlin No.27 is the highest.The CO2 saturation point is 1834.2-2397.5μmol·mol-1,,Changlin No.40 is the lowest,Changlin No.27 is the highest.The carboxylation efficiency is 0.020-0.035,Changlin No.53 is the highest,Changlin No.27 is the lowest.(4)Pn is negatively correlated with Ci,Tair,RH and Tr,positively correlated with Gs and PAR,and has no correlation with C02 concentration.Gs,Ci,Tair,PAR and Tr are the main factors affecting the net photosynthetic rate of 5 clones.Chang Lin No.40,Chang Lin 27 and Chang Lin 53 are also affected by RH.(5)There are significant differences in pigment content between August and November in 5 clones.In August and November,Chang Lin No.27 has the most chlorophyll content.Chang Lin No.3 has the highest carotenoid content,in August,while the content of Chang Lin No.53 is the highest in November.The pigment content in August is lower than that in November,and the chlorophyll a/b value is higher than that in November.(6)There are significant differences in N,P,K and Mg contents between 5 clones in August and November.Chang Lin No.53 has higher nitrogen content,phosphorus content,potassium content and magnesium content than others in August and November.The net photosynthetic rate has significant positive correlation with phosphorus conten,and the correlation coefficient is 0.403.(7)There are significant differences in tree height,ground diameter,crown width,spring length,leaf area,leaf thickness,leaf fresh weight,leaf dry weight,fruit yield per plant and fruit fresh weight among the 5 clones.In the 5 clones tested,the net photosynthetic rate is negatively correlated with tree height,and the correlation coefficient is 0689.The ratio of leaf area,leaf thickness,leaf fresh weight and leaf width to leaf length is positively correlated with net photosynthetic rate,and the correlation coefficients are 0.685,0.685,0.512,0.562 and 0.792 respectively.There is no significant correlation between net photosynthetic rate and ground diameter and fruit yield per plant.