Effect of pruning or removal of in vitro formed roots on ex vitro root regeneration and growth in micropropagated grapes

Pruning or total removal of in vitro formed roots of grape (Vitis vinifera L.) plantlets at planting offered considerable ease and time economy compared to control plantlets with intact roots. The ex vitro establishment was unaffected by the practice with 90% or higher establishment in each treatment. When observed at 4 weeks from planting, growth was slightly affected by root pruning and significantly by root removal. However, both these treatments showed better adventitious root regeneration at the base compared to control plants, which showed elongation of in vitro formed roots with fewer new roots. Root pruning and root removal treatments reduced the influence of the number of in vitro formed roots on vigour of ex vitro plants since the number of new roots formed was independent of the roots initially present. Consequently, these plants showed more uniformity compared to control plants. With a better root system, root pruned plants showed faster subsequent growth. Root pruning at planting is recommended for easier handling and more uniform plants. This revised version was published online in June 2006 with corrections to the Cover Date.