Variation in hormonal levels in sprouting tubers of white potato (Solanum tuberosum L.) [Philippines]
1985
Gonzal, L.R.
Significant varietal differences were obtained in the (a) length of dormancy period, (b) initial indole acetic acid (IAA), gibberellic acid (GA3) and zeatin content of buds but no consistent difference was found in the level of abscisic acid (ABA). A positive correlation between the GA3/ABA ratio and length of dormancy was shown only in 'Fina'. Tubers kept under continuous darkness for a period of one month sprouted earlier than those stored under continuous light. This observation was accompanied by increases in GA3, IAA and zeatin contents one month after bedding. Higher GA3/ABA ratios was also obtained in the dark-incubated tubers. Sprouting of buds in the tubers kept at 10 and 20 C commenced 2 to 4 weeks after bedding while those at 5 C remained dormant for 6 weeks. An increase in ABA content with a corresponding decrease in GA3 content was exhibited by tubers stored at 5 C for one month whilst a higher temperature of 10 or 20 C caused a decrease in the amount of ABA, and an increase in GA3 level. Prolonging the storage period to two months at 20 C generally reduced the IAA and zeatin contents of the tubers. Sprouting and GA/ABA ratios at lower temperature were found to be highly correlated. Treatment with GA3 promoted (a) earlier sprouting of the buds in the tubers, (b) caused excessive elongation of the shoots, and (c) reduced the ABA content of the tubers. On the other hand, application of maleic hydrazide (MH) retarded sprout growth and stimulated the production of ABA resulting to the browning and drying of the shoots. Pretreatment of the tubers with 8 ppm GA3 prior to MH treatment markedly reduced the ABA content
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