Study On The Correlation Between Axillary Bud Length And Endogenous Gibberellin (GA₃) Content In Cut Chrysanthemum

By analysis of leaf endogenous GA3 content at different plant positions of both bud germinationtype cut Chrysanthemum varieties like 'Shenma' and non-bud germination type cut Chrysanthemumvarieties like 'Shenzhi', and by analysis of leaf endogenous GA3 content of non-bud germination typecut Chrysanthemum varieties after breaking the apical domination, the correlation betweencharacteristics of Chrysanthemum buds germination and the endogenous GA3 content was found out andfinally provided a theoretical basis for breeding of non-bud germination type cut Chrysanthemumvarieties and control of characteristics of cut Chrysanthemum bud germination. The results show that: In normal growth circumstances, for bud germination type cut Chrysanthemum variety 'Shenma',buds are all germinated from leaves XY10-XY30. There was significant difference in average length ofaxillary buds in upper (XY32) and lower (XY12) leaves and gradually increasing endogenous GA3content from the leaves of XY10-XY30 with significantly statistical difference of relative and absoluteendogenous GA3 content at the 0.01 level in the upper (XY32) and lower (XY12)leaves. For non-budgermination type cut Chrysanthemum variety 'Shenzhi', buds are all not germinated from leavesXY10-XY30. There were gradually increasing relative endogenous GA3 contents from the leaves ofXY10-XY30 with significantly statistical difference at the 0.01 and 0.05 level, but lower than"Shenma". For bud germination type cut Chrysanthemum variety 'Shenma', the relative content of endogenousGA3 and the germination length of axillary buds were positively correlated with correlation coefficient r=0.989491**. It was also positively correlated between the variation of relative content of endogenousGA3 and the variation of axillary buds length with the correlation coefficient r=0.888318*; while thevariation of absolute content of endogenous GA3 and the variation of bud length were not relatedstatistically which is proved by coefficient r=-0.031714, and the absolute content of endogenous GA3and the length of axillary buds were positively correlated with the correlation coefficient r=0.970505** Only the buds in SY1 and SY3 germinated among the tested leaves of non-bud germination typecut Chrysanthemum variety 'shenzhi' within 20 days after breaking the apical domination. The axillarybuds in leaves SY5, SY10 and SY15 showed not germinated.The relative content of endogenous GA3in the investigated leaves are all on the rise. The relative content of endogenous GA3 in leaves SY1 andSY3 increased remarkable, and the relative content of endogenous GA3 in leaves SY5, SY10 and SY15increased less with statistically significant difference at 0.01 level. The absolute content of endogenousGA3 are also on the rise without statistically significant difference at different plant positions at 0.05 and0.01 levels. It was all positively correlated between the relative content of endogenous GA3 and the length ofaxillary buds in leaves SY1 and SY3 with the correlation coefficients r=0.89982* and r=0.90318*respectively. The experimental results show that higher relative content levels of endogenous GA3 in the plantsare significantly promoting the germination of cut Chrysanthemum and the axillary bud elongation, andthe rapid increase of relative content of endogenous GA3 is good for the axillary buds germination ofcut Chrysanthemum. For the different varieties of cut Chrysanthemum, the relative contents ofendogenous GA3 were significantly different. The relative content of endogenous GA3 could be used asone of the index to judge the germination of cut Chrysanthemum buds. The conclusion of the studyprovides a theoretical basis for regulation of the germination characteristics of cut Chrysanthemumaxillary buds and new variety breeding at the seedling stage, so as to greatly reduce the labor intensityand shorten the breeding cycle, which therefore has important practical significance in cutChrysanthemum breeding.