Induction Of Polyploid Of Populus Davidiana Dode And Populus Simonii×Populus Nigra And Analyses Of Their Growths And Photosynthetic Characteristics

For acquiring triploid by hybridizations of tetraploid and diploid poplar, Populus davidiana Dod. which grows Northeast Chinese mountain land widely and Populus simonii×Populus nigra which is widely cultivated Northeast Chinese plain were selected. For ploidy breeding, induction, growth physiological and photosynthetic characteristics of Populus davidiana Dod. and Populus simonii×Populus nigra polyploidy were studied.Populus davidiana Dod and Populus simonii×Populus nigra were induced with colchicine by seed-immersion method. In all of Populus davidiana Dod.colchicine treatments, the induction rate of the treatments of 0.20% colchicine solution concentration and 48 hours' immersion is highest up to 60%. In all of Populus simonii×Populus nigra colchicine treatments, the induction rate of the treatments of 0.30% colchicine solution concentration and 48 hours' immersion is highest up to 4.49%.The growth physiological and photosynthetic characteristics of polyploid Populus davidiana Dod seedlings were analyzed. These show that:compared with natural diploid, their leaf area become larger significantly, their stomata density become lower dramatically, their soluble protein content increased significantly, their soluble sugar content change significantly. But their height, diameter at ground, chlorophyll content and leaf index do not change significantly(P>0.05). Diurnal variations of net photosynthesis show single peak type, their net photosynthesis reach the highest at about 10:00 all the day. The maximum net photosynthetic rates, apparent quantum efficiency and light saturation points of tetraploid and chimera are higher than natural diploid, the dark respiration rates and light compensation points of tetraploid and chimera are lower than natural diploid. The RuBp regeneration rate, CO2 saturation point of tetraploid are higher than the natural diploid, carboxylation efficiency and CO2 compensatory point of tetraploid are lower than natural diploid. The RuBp regeneration rate, carboxylation efficiency, CO2 saturation point and CO2 compensatory point of chimera are lower than natural diploid. The majority of chlorophyll fluorescence parameters of tetraploid and natural diploid are basically same. Most of chlorophyll fluorescence parameters of chimera are generally lower than natural diploid.The growth physiological and photosynthetic characteristics of Populus simonii×Populus nigra polyploid seedlings show that:their diameter at ground enlarge significantly, their stomata density of polyploid become lower remarkably, their leaf index become smaller significantly. Soluble protein content of tetraploid is higher than diploid significantly. Compared with diploid, their height, chlorophyll content, leaf area and soluble protein content do not change significantly(P>0.05). Diurnal variations of net photosynthesis show double peak type, their first peak generally occur at 9:00 am, their peak-valley generally appear at 13:00 pm, their second peak generally emergence at 15:00 pm. The maximum net photosynthetic rates, apparent quantum efficiency and light saturation points of tetraploid and chimera are higher than natural diploid, the dark respiration rates of tetraploid and chimera are lower than natural diploid's. Tetraploid's light compensation point is lower than natural diploid, chimera's light compensation point is higher than natural diploid. The RuBp regeneration rate and carboxylation efficiency of tetraploid are higher than the natural diploid, CO2 saturation point and CO2 compensatory point of tetraploid are lower than natural diploid. The RuBp regeneration rate, carboxylation efficiency, CO2 saturation point and CO2 compensatory point of chimera are lower than natural diploid. The chlorophyll fluorescence properties of Populus simonii×Populus nigra polyploid are consistent with chlorophyll fluorescence properties of Populus davidiana Dod. polyploid.