| Camellia oleifera is a unique woody oil tree species in China,which is the main economic forest in south China with high economic and ecological benefits.In order to alleviate the intense competition for nutrition between flower buds and fruits and to improve alternate bearing,with'Xianglin 27'-moderate growth vigor and 'Xianglin 14'-strong growth vigor as the experimental materials,spraying different concentrations of gibberellin and paclobutrazol.respectively.By making use of the 13C-isotope tracer technique,the influnce mechanisms of gibberellin and paclobutrazol on flower buds and fruits were explored in the view of nutrient,hormone and source-sink relationship,and the regulation of gibberellin and paclobutrazol of the assimilate allocation from different leaves(sources)to the buds and fruits(sinks).This study not only provided a theoretical basis for the application of exogenous plant growth regulators in Camellia oleifera production,but also offered a technical support for the establishment of high yield and efficiency cultivation system of Camllia oleifera.The main results and conclusion as below:(1)Different concentrations of gibberellin treatments not only significantly increased the differentiation rate and plumpness of flower buds,but also increased the contents of soluble sugar and soluble protein,gibberellin,auxin,and(GA3+IAA)/ABA,and decreased the content of abscisic acid,ABA/IAA and ZT/GA3 in flower buds of 'Xianglin 27' during the flower bud differentiation.Furthermore,the effects of gibberellin at different concentration on the flower buds of 'Xianglin 21' were successively:300 mg/L>200 mg/L>100 mg/L.Different concentrations of paclobutrazol treatments inhibited new shoots growth of 'Xianglin 14',while significantly increased the flower bud differentiation rate,plumpness,contents of soluble sugar and soluble protein,abscisic acid,ABA/IAA and ZT/GA3,and decreased the content of gibberellin in flower buds of 'Xianglin 14' during the flower bud differentiation.Furthermore,the effects of paclobutrazol at different concentration on the flower buds of 'Xianglin 14' were successively:1500 mg/L>1000 mg/L>500 mg/L.(2)Different concentrations of gibberellin treatments significantly increased the contents of soluble sugar and soluble protein in seeds,while decreased the contents of soluble sugar and soluble protein in peels,and significantly increased the contents of gibbereliin,auxin,zeatin and(GA3+IAA)/ABA,while decreased the content of abscisic acid.ABA/IAA and ZT/GA3 in fruits of'Xianglin 27' during the fruit growth period.Furthermore,the effects of gibberellin at different concentration on the fruits of'Xianglin 27' were successively:300 mg/L>200 mg/L>100 mg/L.Different concentrations of paclobutrazol treatments significantly increased the content of soluble sugar in seeds,while decreased the content of soluble sugar in peels.However,the effects of paclobutrazol on the soluble protein content in fruits of 'Xianglin 14' were varied at different fruit development stages:significantly reduced the soluble protein content in seeds at slow growth and mature stages,and increased the soluble protein content in seeds at rapid growth and oil conversion stages:significantly increased the content of soluble protein in peels during the rapid growth and the oil conversion periods,while decreased the content of soluble protein in peels during the slow growth period.In addition,different concentrations of paclobutrazol treatments significantly decreased the contents of gibberellin,auxin,zeatin and(GA3+IAA)/ABA,while increased the content of abscisic acid,ABA/IAA and ZT/GA3 in fruits of 'Xianglin 14'during the fruit growth period.Furthermore,the effects of paclobutrazol at different concentration on the fruits of 'Xianglin 14' were successively:1500 mg/L>1000 mg/L>500 mg/L.Besides,the treatments with gibberellin and paclobutrazol significantly increased the fruit yield characters in the current and following years of 'Xianglin 27' and 'Xianglin 14',respectively,and the most obvious effects were observed in 300 mg/L gibberellin and 1500 mg/L paclobutrazol.(3)Different concentrations of gibberellin treatments significantly increased the chlorophyll content,net photosynthetic rate and chlorophyll fluorescence parameters of the 1st,3rd and 5th leaves during the whole fruit growth stage of 'Xianglin 27'?and improved the photosynthetic performances of leaves.In addition,the effects of gibberellin at different concentration on the photosynthetic characters of 'Xianglin 27' were successively:300 mg/L>200 mg/L>100 mg/L.At oil conversion stage,the chlorophyll content,net photosynthetic rate,maximum photochemical efficiency,photosynthetic electron transfer rate and actual quantum yield of 5th leaf under 300 mg/L gibberellin treatment reached 14.42 ?mol/(m2 s),1.29 mg/g·Fw,0.94,91.01 and 0.22.Different concentrations of paclobutrazol treatments significantly increased the chlorophyll content,net photosynthetic rate and chlorophyll fluorescence parameter of the 1st,3rd and 6th leaves during the whole fruit growth stage of 'Xianglin 14'.and enhanced the photosynthetic capacity of leaves and ensured the efficient photosynthesis.In addition,the effects of paclobutrazol at different concentration on the photosynthetic characters of 'Xianglin 14' were successively:1500 mg/L>1000 mg/L>500 mg/L.At oil conversion stage,the chlorophyll content,net photosynthetic rate and maximum photochemical efficiency,photosynthetic electron transfer rate and actual quantum yield of 6th leaf under 1 500 mg/L paclobutrazol treatment reached 13.98?mol/(m2 s),1.37 mg/g·Fw,0.91,89.90 and 0.22.(4)Different concentrations of gibberellin treatments changed the allocation of 13C-assimilates from different leaf to each organ,especially increased the allocation of 13C-assimilates to the flower buds and fruits,and the effects of gibberellin at different concentration on the allocation of 13C-assimilates of 'Xianglin 27' were successively:300 mg/L>200 mg/L>100 mg/L.At maturity,13C-assimilates allocated from the 1st leaf to the 1st flower bud and fruit were 8.22 mg and 0.57 mg,respectively,which from the 3rd leaf to the 3rd flower bud and adjacent fruit were 7.33 mg and 9.23 mg,respectively,and the amount of 13C-assimilates allocated from the 5th leaf to the adjacent fruit was 17.76 mg under 300 mg/L gibberellin treatment.Different concentrations of paclobutrazol treatments increased the allocation of,3C-assimilates from different leaf to flower buds and fruits,and the effects of paclobutrazol at different concentration on the allocation of 13C-assimilates of 'Xianglin 14' were successively:1500 mg/L>1000 mg/L>500 mg/L.At maturity,13C-assimilates allocated from the 1st leaf to the 1st flower bud and fruit were 3.65 mg and 0.88 mg,respectively,which from the 3rd leaf to the 3rd flower bud and adjacent fruit were 3.27 mg and 8.31 mg,respectively,and the amount of 13C-photoassimilates allocated from the 5th leaf to the adjacent fruit was 12.32 mg under 1500 mg/L paclobutrazol treatment.In summary,the applications of gibberellin and paclobutrazol not only significantly increased the flower bud differentiation rate,plumpness and fruit yield characters for the two consecutive years,and improved the alternate bearing of 'Xianglin 27' and 'Xianglin 14',respectively,but also increased the amount of assimilates from different leaf allocated to flower buds and fruits,and 300 mg/L gibberellin and 1500 mg/L paclobutrazol treatments had the best effects on the increases of flower bud differentiation rate and fruit yield characters for the two consecutive years of 'Xianglin 27' and 'Xianglin14',respectively.Under 300 mg/L gibberellin treatment,the flower bud differentiation rate,seed weight,single fruit weight,kernel rate and yield per plant in the current year reached 38.00%,10.20 g,20.06 g,45.36%and 5.83 kg,respectively,and the fruit number and yield per plant in the following year reached 323 and 4.12 kg,respectively.In addition,Under under 1500 mg/L paclobutrazol treatment,the flower bud differentiation rate,fruit number and yield per plant in the current year reached 31.90%,290 and 4.92 kg,respectively,and the fruit number and yield per plant in the following year reached 244 and 4.04 kg,respectively. |
PDF Full Text Request