The present work aimed to evaluate the effect of the temperature and defoliation on the growth of micropropagated apple plants, cv. 'Marubakaido', during the acclimatization process. Apple shoots were rooted in vitro and transplanted to greenhouse where they remained for fifteen days. After this period, two lots of plants, defoliated and not defoliated, were transferred to growth room and kept under temperature of 4±1ºC and 10±1ºC by 0, 360, 720, 1.080 and 1.440 hours, under 16 hours photoperiod and radiation of 5µE.m-2.s-1. Then, the plants were transferred to greenhouse where their growth was evaluated every two weeks during ten weeks. The internode length and dry matter weight of the aerial part and roots as well were also evaluated at the end of the experiment. The percentage of plant survival was evaluated after a month in a greenhouse. A sharp decrease in the plants survival was verified when they were defoliated and treated at 4±1ºC. Plants with leaves maintained at 4±1ºC presented an increase in the height, internode length and in the weight of the dry matter of the roots and aerial parts proportional to the time remained in this temperature. Plants treated with 10±1ºC had a beneficial effect of the treatments which was also verified for the growth and internode lengthening. Only the plants maintained initially with leaves presented an increase in the dry matter of aerial part in this treatment. 10±1ºC did not affect the weight of roots dry matter of the plants, defoliated and not defoliated.
Malus sp.; micropropagation; plant growth; dormancy; acclimatation; low temperature; correlative inibition
