Studies On Photosynthetic Characters Of Young Trees Of Litchi

The fruit of Litchi chineasis is very delicious and nutritious. Litchi chineasis is one of the most important fruit crops in china, but such problems as extensive management and cultivation, lower fruit set percentage, a more serious dehiscent fruit, unreasonable better strains structure have hindered the exuberance development in Litchi chineasis industry. The studies on photosynthesis of Litchi chineasis not only offer deeper and syntematic understranding on agricultural and physiological characters, aut also provide theory gist.Photosynthesis characteristics of three-year-growth Litchi chineasis were studied under field conditions on three varietirs: Zhuangyuanhong, Feizhixiao,and Nuomichi. Result were shown as follow:l.The net photosynthetic rate (Pn) of leaves has obvious diurnal change.The diurnal variation change of net photosynthetic rate (Pn) of old leaves presented double-peaked or three-peak carve; diurnal Pn variation of young leaves showed one or three peaks .The peak value occurred at 9:00 and 15:00 or so. The most peak value of Zhuangyuanhong is 11. 21 μ mol m^-2 s^-1 , Feizhixiao is 8. 14 μ mol m^-2 s^-1 , Nuomichi is 9. 74 μ mol m^-2 s^-1. Analysis on averaged maximal value and averaged daily Pn showed that Nuomichi (6.3 μ mol m^-2 s^-1) rank first, followed by Zhuangyuanhong(5. 98 μ mol m^-2 s^-1) and Feizhixiao (5. 93 μ mol m^-2 s^-1).2. There was saturated effect of Pn in response to light intensity and Co2 concenteation. The light compensate and saturated points of Litchi Chineasis leaves were 37.4-80.03 μ mol m^-2 s^-1 and 786-1635 μ mol m^-2 s^-1 , respectively. The apparent quantum efficiency were 0. 005 and 0. 0317. Data therefore showed that the leaves of Litchi Chineasis had the higher utilization efficiency on weak light and strong light. The Co: compensate and saturated points were 17. 52-176. 59 μ mol mol^-1 and 654-1450 μ mol mol^-1, respectively. Carboxylating efficiency was between 0. 003-0. 025, which indicated that Litchi Chinese had obvious character of C₃ type plant. Zhuangyuanhong had the higher utilization efficiency on strong-weak light and high-low CO₂ than Nuomichi and Feizhixiao. The propertemperature for photosynthetsis was 26-32.At the same , adaptabilityof Nuomichi and Feizhixiao was better than Zhuangyuanhong.3. The Litchi chineasis variation has obvious seasonal change. The differ variety has some difference. Under field conditions, seasonal variation of Zhuangyuanhong is different from the other two. The seasonal variation of Feizhixiao is similar to that of Nuomichi. The observable Pn vaule in May is the highest while in January is the lowest.4. Under field conditions, the influence of physico-ecological factors on Pn is inner and peripheral, had levity, complexity, and instability.5.There were no remarkable relation between Pn and chlorophyll content , and between specific leaf weight.