Comparative Study On The Effects Of 5-ala On Growth,Photosynthesis,Flavonoids And Polysaccharides Of Taihang Taxus And Taxus Chinensis

In this study,different concentrations of 5-ALA were sprayed on the leaves of five-year-old Taihang wild taxus and taxus chinensis,to study the photosynthetic indexes,fluorescence indexes,growth indexes and related parameters of flavonoids and polysaccharides in taxus under different concentrations in different periods.Numerous studies have shown that 5-ALA promotes growth and improves related qualities in many plants.However,few studies on taxus chinensis by 5-ALA have been reported.This experiment aims to find out the effects of different concentrations of 5-ALA on taxus chinensis in different regions,and filter the optimal treatment concentration that is conducive to the growth and the related quality of Taihang taxus and taxus chinensis.And then accelerate the recovery of taxus resources,and make preparations for the development and utilization of taxus resources.（1）Photosynthetic index parameters in July were higher than in October and April.The photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）and intercellular carbon dioxide concentration（Ci）of Taihang taxus were all the highest under 15mg/L concentration of 5-ALA at different periods.Pn,Tr,Gs and Ci of taxus chinensis were all the highest under 45mg/L concentration of5-ALA at different periods.This indicated that 15mg/L treatment was beneficial to the increase of the photosynthetic index of Taihang taxus,while 45mg/L treatment was beneficial to the increase of the photosynthetic index of taxus chinensis.In this experiment,the total chlorophyll content of taxus chinensis and Taihang taxus treated with 5-ALA increased significantly in each period,while the variation of chlorophyll a/b was higher than that of the control group,but there was no significant difference between the groups.This indicates that 5-ALA is beneficial to generate and increase of chlorophyll content,but has little effect on the distribution of chlorophyll a and b.（2）The relative parameters of fluorescence index are different in different periods,but the trend is the same:the maximum photochemical quantum yield of 5-ALA treatment（F_v/F_m）and light chemical quenching coefficient（q_p）parameters have obvious improve,initial fluorescence（F₀）,and the coefficient of photochemical quenching（NPQ）parameters have significantly lower trend,and the largest fluorescence（F_m）parameters was not obvious difference.F_v/F_m and q_p of Taihang taxus at 15mg/L reached the maximum values in each period,and F₀ and NPQ reached the minimum values at this concentration in each period.F_v/F_m and q_p at 45mg/L treatment of taxus chinensis reached the maximum values in each period,and F₀ and NPQ reached the minimum values at this concentration in each period.The results showed that 15mg/L was beneficial to the increase of F_v/F_m and q_p in the photosynthetic parameters of Taihang taxus and 45mg/L was beneficial to the increase of F_v/F_m and q_p in the photosynthetic parameters of taxus chinensis,and they also decrease of F₀ and NPQ parameters,respectively,but 5-ALA had no effect on the F_m parameters of taxus chinensis.（3）The growth indexes of taxus treated by 5-ALA showed a significant change trend:plant height,ground diameter,and crown amplitude of Taihang taxus treated by 5-ALA reached the maximum at15mg/L,leaf area index is not the largest but has no difference with the maximum treatment.When treated at 45mg/L,plant height,ground diameter and crown amplitude of taxus chinensis reached the maximum.leaf area index was the second highest and the difference with the control group was very significant.In this experiment,all growth indexes of Taihang taxus showed a trend of weakening with the increase of the concentration of 5-ALA treatment,and reached the lowest when concentration was60mg/L,which was significantly lower than that of the control group.However,all growth indexes of taxus chinensis treated by 5-ALA was higher than that of the control group.The results showed that the lower concentration of 5-ALA was beneficial to the growth of Taihang taxus,and it was optimal at15mg/L.The higher concentration treatment was beneficial to the growth of taxus chinensis,and it was best at 45mg/L.（4）The content of flavonoids and polysaccharides was the highest in November,after 5-ALA treatment,the content of flavonoids and polysaccharides in taxus was as follows:the content of flavonoids and polysaccharides in Taihang taxus increased most significantly after 45mg/L treatment and reached the highest in November.The content of taxus chinensis increased most significantly at 60mg/L,reached the highest level in November,while the content of flavonoids showed no significant difference after 5-ALA treatment.This indicated that 45mg/L 5-ALA treatment was beneficial to the accumulation of flavonoids polysaccharides in Taihang taxus,while 60mg/L 5-ALA treatment was beneficial to the accumulation of polysaccharides in taxus chinensis.