Photosynthetic And Nutrition Physiology Of Korean Pine With Different Fruit Characteristics During Flower Bud Differentiation

Flower bud differentiation is one of the important stages of plant growth and development.Its status directly affects the quantity and quality of seeds.At present,the research on flower bud differentiation of conifer is less,the research on flower bud differentiation mainly focuses on four aspects: fruit trees,flowers,crops and vegetables.The research on the fruiting of Korean pine mainly focuses on the macro level and group level,and less on the individual level.Therefore,taking individuals with different fruit of Korean pine characteristics as the object,this study measured the photosynthetic capacity of Korean pine needles and endogenous substances in Korean pine terminal buds,analyzed their changes during flower bud differentiation,and discussed the effects of fruit.The results are as follows:(1)The photosynthetic capacity of Korean pine needles increased gradually with the process of flower bud differentiation.Net photosynthetic rate(Pn),intercellular carbon dioxide concentration(Ci),maximum net photosynthetic rate(Pmax),chlorophyll a(Chla),chlorophyll b(Chlb)and total chlorophyll(Chl T)increased with time,while stomatal conductance(Cond),light compensation point(LCP)and dark respiration rate(Rd)decreased with time.Korean pine needles can ensure the nutrition supply of flower buds and fruits by increasing photosynthetic rate and chlorophyll,reducing respiratory loss and enhancing the ability to use weak light.(2)There was no significant habitat difference in photosynthetic capacity of Korean pine needles.Ci,LCP,RD,Chla,Chlb,Chl T and chlorophyll a/b(Chla/b)of needle leaves were:Korean pine at forest edge > Korean pine in forest.Korean pine at the forest edge has strong respiration,high chlorophyll concentration and strong ability to use weak light.(3)There was no significant fruit difference in photosynthetic capacity of Korean pine needles.Pn,Cond,apparent quantum efficiency(AQY),LCP,RD,Chla,Chlb,Chl T,Chla/b all showed that: more fruit Korean pine > less fruit Korean pine.The more fruit Korean pine increased the photosynthetic rate and chlorophyll concentration of needles,and enhanced respiration.The photosynthetic capacity of Korean pine needles individuals with more fruit was 20% higher than that of Korean pine individuals with less fruit.(4)The endogenous substances in the terminal buds of Korean pine showed the characteristics of periodic changes with the process of flower bud differentiation.High levels of soluble sugar,carbon/nitrogen(c/n),abscisic acid(ABA),cytokinin(CTK),auxin(IAA),ABA/CTK,ABA/GA,and low levels of starch,gibberellin(GA),ABA/IAA,CTK/GA,GA/IAA were beneficial to the flower bud differentiation of Korean pine.(5)There was no significant habitat difference in the endogenous substances of the terminal buds of Korean pine.The change of microenvironment had little effect on the flower bud differentiation of Korean pine.(6)There was no significant fruit difference in endogenous substances of the terminal bud of Korean pine.The non-structural carbohydrates in the terminal buds of the more fruit Korean pine were 10% higher than those of the less fruit Korean pine.There is no obvious nutritional competition between fruit and flower bud.The existence of fruit had no effect on the normal differentiation and development of flower buds.In general,the photosynthetic capacity of Korean pine needles increased with time,which ensured the normal process of flower bud differentiation and fruit development.The endogenous substances in the terminal buds showed periodic changes with time,which was closely related to the process of flower bud differentiation of Korean pine.The change of microenvironment had a certain effect on the photosynthetic capacity of Korean pine needles,but had little effect on the endogenous substances of terminal buds.The individual needles of more fruit Korean pine had stronger photosynthetic capacity.The non-structural carbohydrates and gibberellin in the terminal buds of Korean pine may be related to the formation of individual fruit characteristics.