美洲黑杨无性系苗木对不同光周期处理的生长与生理响应1

[Objective]To study the performance of plant growth traits of Populus deltoides clones under different photoperiod treatments,screen the traits that can effectively evaluate photoperiod sensitivity of Populus deltoides,and clarify the effect of photoperiod on physiological status of Populus deltoides clones with different sensitivity.[Methods]With 26 clones of Populus deltoides as research materials,the artificial climate room was used to set up two photoperiod treatments(light 16h/dark period 8h,light 8h/dark period 16h).Through continuous observation and analysis of 12 growth traits of Populus deltoides at multiple time points under different photoperiod treatments,the subordinate function method and principal component analysis were used to obtain the comprehensive evaluation index D value of photoperiod sensitivity of growth traits of Populus deltoides.The direct effect index of photoperiod sensitivity of Populus deltoides was selected by regression analysis and path analysis,and the physiological indexes of Populus deltoides clones with different photoperiod sensitivity were measured and analyzed simultaneously with the growth monitoring.[Results]1)The results of variance analysis showed that there were significant differences in 12 growth traits of Populus deltoides under different photoperiod treatments(p<0.05).The leaf length,leaf width,leaf area and specific leaf area of Populus deltoides under short photoperiod were significantly greater than those under long photoperiod,while the net growth value of plant height,net ground diameter,dry weight of leaf,fresh weight of stem segment,fresh weight of root system,dry weight of stem segment The observed values of root dry weight and node number were significantly lower than those of long photoperiod.2)The analysis results of D value of comprehensive evaluation index for photoperiod sensitivity of Populus deltoides showed that four indexes,including fresh weight of stem segment,number of nodes,net growth value of ground diameter and net growth value of plant height,had a greater direct effect on the comprehensive evaluation value of photoperiod sensitivity(0.113-0.338),which could be used as the character index for evaluating photoperiod sensitivity of Populus deltoides.Among them,net growth value of plant height was more suitable for practical production.3)The comprehensive comparison of photoperiod sensitivity of 12 characters showed that different clones in the same source had different photoperiod sensitivity.Among the 26 clones of Populus deltoides,LS8,TN3 and WA1 had the highest photoperiod sensitivity,and QB7,LS5 and TN6 had the lowest photoperiod sensitivity.Three clones with high growth and high photoperiod sensitivity,LS9,LS4 and TN4,and three clones with low growth and low sensitivity,QB7,QB2 and QB4,were selected based on the growth performance of plants.4)The Rubisco activity,TPI activity and FBA activity of clones with high growth and high sensitivity under long photoperiod treatment increased with the increase of treatment time.The total chlorophyll content decreased first and then increased.The GS activity decreased gradually with the increase of treatment time.Under short photoperiod treatment,the Rubisco activity increased first and then decreased,and the total chlorophyll content decreased gradually;Rubisco activity and total chlorophyll content of clones with low growth and low sensitivity decreased gradually with the increase of treatment time.Under the treatment of short photoperiod,their FBA activity first decreased and then increased,and Rubisco activity generally decreased with the increase of treatment time;The changes of physiological enzyme activities and total chlorophyll content of different Populus deltoides clones were different under different photoperiod treatments.[Conclusion]The growth characters of Populus deltoides are significantly affected by photoperiod,among which the net growth value of plant height,net growth value of ground diameter,fresh weight of stem segments are more sensitive to strong photoperiod,which can be used as the character indicators for evaluating photoperiod sensitivity of Populus deltoides.Combined with the net growth value of plant height,high growth sensitivity and low growth sensitivity types of clones can be divided.The physiological responses of Populus deltoides with different photoperiod sensitivities to photoperiod changes are significantly different.The FBA activity and GS activity of clones with high sensitivity are more sensitive to long photoperiod changes.The Rubisco activity of Populus deltoides with different photoperiod sensitivities shows a reverse change trend under long photoperiod,which may lead to the growth differences of Populus deltoides with different photoperiod sensitivities.The two types of photoperiod sensitivity of Populus deltoides screened out can lay a foundation for breeding new varieties of Populus deltoides with wide adaptability across climate regions and for studying the molecular mechanism of photoperiod sensitivity of Populus deltoides.