The Study Of Photosynthesis And Chlorophyll Fluorescence Characteristics Of Grafted Alnus Ledgeriana Seedlings From Different Provenances

Alnus ledgeriana has strong adaptability and wide use of wood.It is listed as a high-quality paper-making tree species.It is a fast-growing timber species in southwestern China and an important native tree species in Sichuan Province.It has broad prospects for development.This test passed study the photosynthesis and chlorophyll fluorescence characteristics of grafted Alnus ledgeriana seedlings from different provenances,screen out the excellent provenances suitable for regional development,it provides building materials for the construction of the Alnus clone primary seed garden and the national Alnus breeding base,and provide basic data for scientifically formulating the Alnus ledgeriana forest management measures,introduction cultivation and Promotion application.In December 2015,Collecting Alnus ledgeriana cuttings from four provenances of Enyang,Jintang,Pingchang and Xuanhan,Alnus ledgeriana seedlings with 1 year old and the growth is basically the same are selected as rootstocks.Adopt randomized block design method and graft in January 2016.In August of the same year,the plant height,root diameter,biomass,photosynthetic parameters,chlorophyll content and fluorescence kinetic parameters of the grafted seedlings were determined.The study found:?1?The plant height,base diameter and biomass of the seedlings of Pingchang provenance were the largest,and the basal diameter and biomass were significantly higher?P<0.05?than other provenances.In addition,the plant height of Pingchang and Jintang provenance seedlings was not significantly different?P>0.05?,and significantly?P<0.05?was greater than Enyang and Xuanhan provenances.It indicated that the seedlings of Pingchang provenance were the best,and the Jintang seedlings were the second.The Enyang and Xuanhan provenances were poor.?2?There were significant photosynthesis rate,stomatal conductance,transpiration rate,light compensation point,light saturation point,apparent quantum efficiency,CO₂compensation point,CO₂ saturation point and carboxylation efficiency among the seedlings of four provenances of Alnus ledgeriana?P<0.05?.All of the Pingchang provenances of Alnus ledgeriana grafted seedlings were significantly?P<0.05?larger than other provenances.The grafted seedlings of Jintang provenance were significantly?P<0.05?larger than the Enyang and Xuanhan provenances.It indicated that the Pingchang provenance of eucalyptus seedlings had the highest photosynthesis and the strongest ability to adapt to the environment.The Jintang provenance was the second,and the Enyang and Xuanhan provenances were poor.?3?The photosynthetic pigment content of the seedlings of Pingchang seedlings Alnus ledgeriana grafted was the highest.Among them,chlorophyll a was 4.94 mg·g^-1,chlorophyll b was 2.07 mg·g^-1,total chlorophyll was 7.01 mg·g^-1,and carotenoid was 0.85 mg·g^-1,both of which were associated with Jintang provenance.The difference of grafted seedlings was not significant?P>0.05?,and significant?P<0.05?was greater than that of Enyang and Xuanhan provenances.The chlorophyll a/b value of Xuanhan provenance seedlings was 3.14,and the carotenoid/total chlorophyll value was 0.17,which was significantly higher than other provenances?P<0.05?and may be stressed by high temperature and strong light.There was no significant difference in chlorophyll a/b value and carotenoid/total chlorophyll value between Pingchang and Jintang provenances?P>0.05?.It indicated that the seedlings of four provenances of Alnus ledgeriana had certain ability to resist glare damage and protect photosynthetic apparatus,and the Pingchang and Jintang provenances of Alnus ledgeriana grafted seedlings had strong ability to resist glare damage and oxidative stress,Enyang and Xuanhan provenances.The protection ability is weak.?4?The initial fluorescence?F_O?of the grafted seeds of Xuanhan provenance Alnus ledgeriana was significantly higher?P<0.05?than other provenances.The difference of maximum fluorescence?F_m?of the four provenances was not significant?P>0.05?.The variable fluorescence?F_v?and maximum photochemical efficiency?F_v/F_m?of Pingchang provenance were not significantly different from those of Jintang?P>0.05?,and significantly?P<0.05?were greater than Enyang and Xuanhan provenances.In addition,the maximum electron transport rate,potential photochemical efficiency?F_v/F_O?,actual photochemical efficiency??PSII?,photochemical quenching coefficient:?qP?and non-photochemical quenching coefficient?qN?of Pingchang provenance were significantly higher?P<0.05?than other provenances.It indicated that the Pingchang seeding Alnus ledgeriana grafted seedlings had the strongest ability to absorb light energy,and the electron transfer rate was the fastest,and it could protect the photosynthetic mechanism by adjusting the electron transfer rate and route and increasing heat dissipation.The self-regulation ability was the strongest.The self-regulating ability of grafted seedlings of Jintang provenance Alnus ledgeriana was second,and the sources of Enyang and Xuanhan were weak.In summary,there were significant differences in growth,photosynthesis and chlorophyll fluorescence characteristics between the four seedlings of Alnus ledgeriana grafted seedlings.Pingchang provenance Alnus ledgeriana grafted seedlings have strong ability to resist glare damage and oxidative stress by regulating electron transfer rate and pathway,increasing heat dissipation,etc.,which can better protect photosynthetic apparatus,with the highest photosynthetic pigment content and the strongest photosynthesis.optimal.Enyang and Xuanhan seedlings Alnus ledgeriana grafted seedlings have weak self-regulation ability,are vulnerable to glare damage,poor photosynthesis and weak growth.Jintang provenance Alnus ledgeriana grafted seedlings have stronger self-regulation mechanism,stronger photosynthesis and better growth.Therefore,according to the photosynthetic and chlorophyll fluorescence characteristics of different provenances of Alnus ledgeriana,the suitable areas for development can be selected,and the Alnus ledgeriana grafted seedlings suitable for regional development can be selected according to the business purpos...