| Many photosynthetic characteristics pf three plum varieties were studied with a infrared CO2 analyzer0 The photosynthetic charaters of plum and the the effects of environment facters were discussed, which filled the gap on study of plum photosynthesis,The trials were conducted from May to October, 2000, at the Horticultural Experimental Station of the Northeast Agricultural University0 The results show?N Diurnal change in net photosynthetic rate (Rn) in plum leaves was a typical nonerop?bimodal curve0 The supreme peak appeared at 10:00a.m. , and the see?ndry peak at 15:OOp.m.adout0 During 12:00p.m. to 14:OOp.m. the Pn reduced visibly0 Other physiological and ecological indexeswere positively or negatively interrelated with Rn0 The seasonal change in Rn was bimodal curve, in which the first period of high Rn was late June and the second was late August. The pho?osynthetic actives of plum were prosperous during the period from June 10th to September 10th when the Pn remained a comparely stable high value02~ the leaf age had an imatate relation with Pn0 The negative value period in Rn in plum leaves were 5 to 6 days0 On 25 to 28 days it arrived the top, and the high values might remain 110 days0 The leaf area, chlorophyll (chl) and specific leafweight(SLVOhad positively interrelationswithPn0lnmature leaves, there was no interrslation between Rn and chl0 The morphological characters of leaves had important relations with Pn0 The stomatal density and the ratio of rail organize and sponge organize might be cornparely important facters to leaf?s assimilation mount and steaming efficient03~ Onthe samebraneh, leaf?s loeationsaffectedPn0 Themiddleandupiddle sites, leaves h~id high Rn ues and high stablilities0 The top Pn sites shifted uotward with season change0 In different locations of canopy, there were different PAR and Pn which had positive interrelation, that indicating light might be one of main reasons for difference in En in canopy location0 Branch types affected Pn too0 Short fruit twigs and bouguetamed fruit twigs had highest Pn values than other types0 Pruned nutritional twigs had similar Pn with long and middle?length twigs, with long nutritional twigs lowest04~ Plum leaf?s lightPn curve was a hyperbold0 The light compensation points were at 60?5 i.i mA. m -. s with light saturation points at l300?570 ~t mol. m< s~ Pn in Plum leaves changed with temperature0 The suitable temperature scope and best suitable temperature changes with season altertion, whiah were separately 20?2C, 240C and 24?6~C, 28~C on æ—¿une and August0 The soil water content affected Pn0 In drought trial. Pn f1rstly rised then droped, with chl content droping0 Under severE drought. plum leaves turned yellow0 The suitable soil water content was 60% to 85%. and irrigating deadline was 30% to 50%.Postgraduate:Xu JiaoHuiMajor:PoniologyTutor:Yu ZeYuanDate:May, 2001... |
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