CHILLING AND GA₃ EFFECTS ON GROWTH AND DEVELOPMENT OF 'NEMAGUARD' AND 'GF 305' PEACHES

The effect of different chilling and gibberellin treatments on growth and development of the peach rootstocks ‘Nemaguard’ and ‘GF305’ was studied. A factorial experiment was designed combining cold treatments (0, 5, 15 and 30 days at 4°C temperature) and GA₃ concentrations (0, 100 and 200 mg/L). The variables considered were: percentage of germination, number of internodes, plant height and the ratio plant height/number of internodes. Results showed an overall growth increase as a consequence of chilling and gibberellin addition; however the behaviour of the two assayed rootstocks was slightly different. In general terms, ‘Nemaguard’ responded well to 5 days cold and chilling treatments did not improve growth in a relevant way, whereas ‘GF305’ showed a more gradual effect of the chilling and gibberellin treatments on the studied parameters.