| With the advantages of early bearing, high yield, top quality and convenientmanagement, high density dwarf culture of apple has become a trend in modern appleproduction. And application of dwarf rootstock becomes the main way in high densitydwarf culture of apple. While the upgrade and application of dwarf rootstock is limited bydifferent preliminary selection methods. Quick and accurate preliminary selection methodis conductive to early screening of apple hybrid seedling, thus reducing costs of fieldmanagement and accelerating breeding progress of dwarf rootstock Vigorous、semi-dwarfing and dwarfing rootstocks were used to compare their difference on themorphologic and physiological indexes, the results was applied on another27candidaterootstocks, to getting appropriate indicators which can be used to forecast the dwarfingability, and screen out dwarfing rootstocks.The results showed that:1. The branch-cortex ratio of rootstocks was markedly different among the vigorousrootstocks, semi-dwarf rootstocks and the dwarf rootstocks.The branch-cortex ratio ofsemi-dwarf rootstocks was obviously higher than that of vigorous rootstocks, andobviously lower than that of dwarf rootstocks.2. There were significant differences in stomata density in different rootstocks. Thestomata density in dwarf rootstocks was obviously lower than that in semi-dwarfrootstocks and vigorous rootstocks. The stomata horizontal diameter in different rootstockswas not significantly different, while the stomata vertical diameter in dwarf rootstocks wasobviously higher than that in semi-dwarf rootstocks and vigorous rootstocks.3. The POD and IOD activity in leaves were significantly different in rootstocks withdifferent dwarfing ability. The POD and IOD activity of leaves in vigorous rootstocks wereobviously lower than those in semi-dwarf rootstocks and dwarf rootstocks. SOD activity ofleaves showed significantly different in different periods and in different rootstocks, butthere was no correlation between SOD activity and dwarfing ability of rootstocks. On May30th, CAT activity of leaves in semi-dwarf rootstocks was obviously higher than that indwarf rootstocks and obviously lower than that in vigorous rootstocks. CAT activity waslower on September30ththan that on May30th. And the CAT activity of leaves in vigorousrootstocks was obviously higher than that in semi-dwarf rootstocks and dwarf rootstocks.But it showed no obvious difference between semi-dwarf rootstocks and dwarf rootstockson September30th.4. The content of endogenous hormones IAA in leaves showed great differences in different rootstocks, so did ABA, GA3and ZR. And each of IAA, ABA, GA3and ZR hadno obvious correlation with dwarfing ability of rootstocks. The ratios of IAA/ABA,（IAA+GA3+ZR）/ABA in dwarf rootstocks were both significantly lower than those insemi-dwarf rootstocks and vigorous rootstocks. Both of the ratios of IAA/ABA,（IAA+GA3+ZR）/ABA were not obviously different between semi-dwarf rootstocks andvigorous rootstocks respectively. And the ratios of GA3/ABA、ZR/ABA among differentrootstocks showed no significant differences respectively.5. The contents of nitric oxide in leaves of different rootstocks were markedlydifferent during the same period. The nitric oxide content in leaves of semi-dwarfrootstocks was markedly higher than that of dwarf rootstocks, and markedly lower thanthat of vigorous rootstocks.6. The polyamines content in leaves of different rootstocks during different periodsshowed that the putrescine (Put) content in vigorous rootstocks was obviously higher thanthat in semi-dwarf rootstocks and dwarf rootstocks. The content of spermidine(Spd)、polyamines (PAs) in semi-dwarf rootstocks were significantly lower than those in vigorousrootstocks respectively, and significantly higher than those in dwarf rootstocks. Thecontent of spermine (Spm) in semi-dwarf rootstocks was significantly higher than that indwarf rootstocks, and significantly lower than that in vigorous rootstocks on September30th. The ratios of Put/(Spd+Spm) in leaves of different rootstocks during the same periodhad no significant differences, so did the ratios of Put/Spd, Put/Spm and Spd/Spm.7. On May30th, Ca2+content in leaves of vigorous rootstocks was obviously lowerthan that in semi-dwarf rootstocks and dwarf rootstocks. On September30th, the contentsof Ca2+in leaves of different rootstocks increased significantly, and the Ca2+content indwarf rootstocks was obviously higher than that in vigorous rootstocks, and obviouslylower than that in semi-dwarf rootstocks.8. After analyzing the correlation between each indicators and the dwarfing degree ofthe rootstocks, we think the branch-cortex ratio, stomatal density, IOD activity, CATactivity, spermidine content, polyamines content and nitric oxide content are the primaryindicators for screening dwarfing rootstock, and then screen the candidate rootstocks basedon these indicators.Through analyzing the four parameters of the selected rate,leak-election rate, wrong choice rate and accuracy, we think that the branch-cortex ratio,stomatal density, total polyamines and nitric oxide content were suitable indicators forscreening dwarfing rootstock.According to the four selected indicators, seven dwarf rootstocks, ST, No.2, No.6,SH37, No.28, No.111and No.178were preliminarily selected from27candidate rootstocks,after comparing witn their actual growth potential, we get the accuracy of the selection is85.71%。... |
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