Study On The Difference Of Photosynthetic Characteristics And Leaf Features Of Five New Varieties Pear

The experiment was carried out in ’red Bartlett’ pear,’early Bartlett’,’Huangguan’ pear,’Yuluxiang’pear and ’Shuofeng’ pear,the photosynthetic indexes(including net photosynthetic rate,transpiration rate,stomatal conductance and intercellular CO2 concentration)and Light response curves of photosynthesis of five pear varieties were determined by portable photosynthesis system Li-6400.The chlorophyll content,CCI and Leaf traits were also investigated.The main results were as follows.(1)The diurnal variations of photosynthetic rate of five pear varieties behaved as double-peak pattern.The first peak of photosynthetic rate appeared at 10:00 am and the lowest valley of photosynthetic rate appeared at 13:00 am.(2)The diurnal variation curve of PAR was single peak type;The diurnal variation curve of air relative humidity(RH%)was "V" type,which was the first decline after the trend,contrary to PAR,the diurnal variation of the temperature;the diurnal variation of ambient temperature was similar to that of PAR,showing a single peak type;The diurnal variation of environmental co2 concentration was U-shaped curve,which was the same as that of photosynthetic active radiation and temperature.The Pn was positively correlated with PAR and Ta,negatively correlated with RH and Ca,and the correlation coefficients were Ta>PAR>RH>Ca.(3)the daily changes of Gs and Tr of five pear varieties presented as bimodal curve which was similar as Pn;the diurnal variations of Ci which was opposite to Pn was bimodal curve;the diurnal variations of WUE presented as bimodal curve,There is a significant difference between five pear varieties.Pn was significantly positively correlated with Gs,Tr and WUE,and negatively correlated with Ci.The correlation coefficients were in the order of Tr>Gs>WUE>Ci.According to the relevant analysis,PAR,Tr,Gs,Ci,WUE were important factors for Pn of of five pear varieties.(4)The range of LSP of five pear varities was 12142.9～1521.4 μmol ·m-2·s-1.The order(from higher to lower)was:Shuofeng pear>early Bartlett pear>huangguan pear>Yuluxiang pear>red Bartlett pear;the order(from higher to lower)of Pm was:Shuofeng pear>Yuluxiang pear>red Bartlett pear>huangguan pear>early Bartlett pear;the range of LCP was 63.2～89.4μmol·m-2·s-1,the order(from higher to lower)was:huangguan pear>Shuofeng pear>red Bartlett pear>Yuluxiang pear>early Bartlett pear;the order of AQY was:red Bartlett pear>Shuofeng pear>huangguan pear>Yuluxiang pear>early Bartlett pear.LCP,LSP of Yuluxiang pear are low,indicating that the ability to adapt to low light is strong.The LCP of the early Bartlett pear is low and the LSP is high,which indicates that it has not only good resistance to low light,but also has good adaptability to bright light.LSP,Pm of ShuoFeng pear are high,it was fit for growing in the weak and intense light.(5)The order(from higher to lower)of CCI index of five pear varities was:Yuluxiang pear>red Bartlett pear>early Bartlett pear>Shuofeng pear>huangguan pear;the order(from higher to lower)of Chla was:Yuluxiang pear>red Bartlett pear>early Bartlett pear>huangguan pear>Shuofeng pear;the order(from higher to lower)of the Chlb was:early Bartlett pear Yuluxiang pear>red Bartlett pear>huangguan pear>Shuofeng pear;the order of ChlT was:huangguan pear>red Bartlett pear>Yuluxiang pear>Shuofeng pear>zao Bartlett pear;the order(from higher to lower)of Chla/Chlb was:huangguan pear>red Bartlett pear>Yuluxiang pear>Shuofeng pear>early Bartlett pear.The chlorophyll content of early Bartlett pear was the highest,while Chla/Chlb was lower.It’s More suitable for facility cultivation.(6)The order(from higher to lower)of petiole length of the five pear varities was:Shuofeng pear>Yuluxiang pear>early Bartlett pear>huangguan pear>red Bartlett pear;The order(from higher to lower)of Blade thickness of the five pear varities was:Shuofeng pear>huangguan pear>>early Bartlett pear>Yuluxiang pear>red Bartlett pear;The order(from higher to lower)of petiole weight of the five pear varities was:huangguan pear>early Bartlett pearr>Shuofeng pear>Yuluxiang pear>red Bartlett pear;The order(from higher to lower)of Leaf area of the five pear varities was:huangguan pear>Yuluxiang pear>Shuofeng pear>red Bartlett pear>early Bartlett pear.(7)The number of stomata of the huangguan pear in the five pear varieties was the largest,Yuluxiang pear is lowest.The stomatal length of the five pear varieties was the longest,and Shuofeng pear was the smallest,and the difference was significant between Yuluxiang pear、red Bartlett pear and the others.The stomata porosity of the five pear varieties was the widest,and the difference was significant with the other pear cultivars,Shuofeng pear is lowest.Red Bartlett pear is much larger than that of several other varieties in the Stomatal area,Shuofeng pear is lowest.