Ethylene Evolution Stimulated by Succimc Acid-2,2-Dimethylhydrazide in Apple Shoots

The rate of ethylene production in the shoot tips of the apple cultivar ‘Ingrid Marie’ (Red motant) after succinic acid-2,2-dimethylhydrazide (SADH) treatment was investigated. The shoots were treated with SADH at 12.5, 25 or 50 mM in the months of June, July and August. The samples were analysed 7,15, 30 and 60 days after SADH spray. Ethylene production was considerably higher in the SADH-treated shoots than in the untreated ones. Application of 12.5 or 25mMSADH late in June stimulated ethylene production 3-fold, while 50 mM produced a 5-fold increase in ethylene production 7 days after spraying. There was a continuous decrease in ethylene production at the subsequent samplings. In untreated control shoots there was a slight increase. However, even 60 days after spraying the shoots treated with 50 mM had higher ethylene production than the control shoots. The same relationship was found in the shoots treated in the months of July and August. A parallelism has been established between the rate of ethylene production and growth retardation, A residual effect of SADH treatment in earlier years was demonstrated and is discussed.