The Effect of Multiplication Number In Vitro on Juvenility of Kiwifruit Plants (Actinidia deliciosa A. Chev.)

Sometimes a longer juvenility phase is observed on micropropagated plants, in orchard, during the first two-three years after planting. The high number of multiplication in vitro of the same explants could influence this phenomenon. This study aimed to investigate anatomical and genetic modifications induced in kiwifruit plants by micropropagation. Trials were carried out using plants micropropagated and obtained by cuttings. Shoots of 'Hayward' clone H8 were cultured in vitro and multiplied 60, 30 and 8 times respectively. In vitro multiplication rate of the material which was subjected to 60 multiplications was constantly greater, and the number of plants obtained ready to acclimatization phase doubled in this case. Plant height, shape and size of leaves, tomentosity density and distribution, number and size of xylem vessels were evaluated and differed significantly. The characteristics of micropropagated plants resulted to be related to the number of in vitro cycles. The phenomena evolution will also be followed out in field condition until maturity to compare yield and fruit quality.