Comparison of growth,photosynthetic,and chlorophyll fluorescence characteristics of different native cultivars in Castanea henryi

XU Bin; WU Jingyi; WU Jianfeng; SU Xinyu; ZHAO Junru; ZHU Zhoujun; LI Jianxin

doi:10.13925/j.cnki.gsxb.20240702

Abstract：[Objective]The production of Castanea henryi is a new industry in Guizhou province of Chi-na.Many native cultivars have been introduced from Fujian province in resent years.Their adaptability remains unclear.The study systematically evaluated the photosynthetic characteristics and chlorophyll fluorescence parameters of 8 C.henryi native cultivars from Fujian in order to provide a scientific basis for the cultivation of C.henryi in Qiandongbei region of Guizhou province.[Methods]This experi-ment was conducted in mid-July at the Woody Oil Crop Base of Tongren University(27°47′30″ N,109° 13′16″ E,altitude 466.2 m).The two-year-old grafted trees of 8 native cultivars of C.henryi introduced from Fujian were used as experimental materials.The density of the trees were 4 m×4 m in the plot un-der conventional irrigation and fertilization management.The relative chlorophyll content(SPAD)was measured using a SPAD-502Plus chlorophyll meter.The leaf area,length,and width were then mea-sured with a Li-3000C portable leaf area meter.The photosynthetic parameters were measured between 08:30 and 11:30 on clear days using an Li-6800 portable photosynthesis system.The target leaves were marked and subsequently photoinduced at a light intensity of 1200 μmol·m-2·s-1 for at least 20 minutes until stabilization of the net photosynthetic rate(Pn).The light-response curves were fitted through a rectangular hyperbolic correction model,with parameters recorded including maximum net photosyn-thetic rate(Pnmax),light saturation point(LSP),apparent quantum efficiency(AQY),light compensation point(LCP),and dark respiration rate(Rd).The chlorophyll fluorescence analysis was conducted through overnight dark-adaptation of the leaves achieved by aluminum foil wrapping.With the Li-6800 system maintained at identical chamber settings to those used for light-response curve measurements,a 30-minute light adaptation was performed before parameter determination.The recorded parameters in-cluded:initial fluorescent light(F0);maximal fluorescence(Fm),PS Ⅱ primary light energy conversion efficiency(Fv/Fm),potential efficiency of primary conversion of PS Ⅱ(Fv/F0),actual photochemical effi-ciency of PS Ⅱ(Fv′/Fm′),photochemical quenching coefficient(qP),electron transport rate(ETR),and non-photochemical quenching(NPQ).The Mantel test was applied to conduct correlation analysis for examining the relationships among growth parameters,photosynthetic parameters,and chlorophyll fluo-rescence parameters.The principal component analysis was applied to identify dominant characteristic parameters between photosynthetic parameters and chlorophyll fluorescence parameters.[Results]The significant growth variations were observed in the growth indexes of different native cultivars of C.hen-ryi.Among all tested cultivars,Youzhen exhibited superior performance in plant height(96.18 cm),ground diameter(20.79 mm),and leaf area(76.15 cm2),all significantly higher than those of the other cultivars(P＜0.05).The SPAD values of Youzhen and Dajianzui were significantly higher than those of the other cultivars(P＜0.05).Although the 8 cultivars displayed similar trends in light-response curves,they differed significantly in the key photosynthetic parameters.The AQY ranged from 0.042 to 0.059,with Youzhen and Dajianzui exhibiting the highest values of 0.059.The Pnmax of Bailuzi was significant-ly lower than that of other cultivars.Changmangzi exhibited the lowest Rd,while Heili had the highest Rd.Meanwhile,Heili had the highest LCP and LSP.The significant variations in chlorophyll fluores-cence parameters were observed among 8 C.henryi cultivars.The initial fluorescent light(F0)of Bailuzi was significantly higher than that of other cultivars(P＜0.05).The correlation analysis revealed that plant height had a highly significant and positive correlation(P＜0.01)with ETR,AQY,LSP,LCP,and Rd.The Pnmax was positively correlated with Fm,Fv/Fm,Fv/F0,and Fv′/Fm′,while it was negatively cor-related with NPQ.Furthermore,the Fv/Fm,Fv/F0,and Fv′/Fm′ showed a highly significant and positive correlation(P＜0.05).The chlorophyll fluorescence parameters of Youzhen and Dajianzui were similar,but the NPQ value of Dajianzui was significantly lower than that of Youzhen.Additionally,both You-zhen and Dajianzui showed relatively high values of the Fv′/Fm′ and ETR.The Fv′/Fm′ of Youzhen was 0.755 and the ETR was 114.677,while those of Dajianzui were 0.765 and 107.148,respectively.The Fv/F0 of Youzhen was not significantly different from that of Chushuhong,but was significantly higher than that of the other 6 cultivars(P＜0.05).The principal component analysis(PCA)grouped the 13 photosynthetic physiological characteristics into two principal components with a cumulative contribu-tion rate of 77.48％,among them,the first principal component was closely related to Fv/Fm,Fv/F0,and Fv′/Fm′,with a contribution rate of 53.72％,while the second principal component was related to LSP and ETR,with a contribution rate of 23.76％.Based on the analysis of the data distribution related to the growth and physiological characteristics of C.henryi cultivars,Youzhen,Dajianzui,and Wukechang-mang were closely clustered together in the data distribution pattern.In contrast,Heili and Bailuzi were located far away from the other six native cultivars in the same data distribution context.[Conclusion]The significant variations in growth parameters and photosynthetic physiological characteristics were observed among different C.henryi native cultivars from Fujian.The Youzhen cultivar demonstrated su-perior growth performance and high light-use efficiency,consistent with its growth parameter perfor-mance,indicating better adaptability in the Qiandongbei region of Guizhou province.