Comparison of growth characteristics between diploid and colchicine - Induced tetraploid grape rootstocks

Autotetraploids of three grape rootstocks, 'Gloire de Montpellier' ('Gloire', Vitis riparia Michx), 'Rupestris St. George' ('St. George', V. rupestris Scheele), and 'Couderc 3309' ('3309', V. riparia X V. rupestris), were induced by the colchicine treatment of micropropagated plantlets. Doubling of chromosomes in the selected colchicine- treated clones was confirmed by flow cytometric analysis of the immature leaves. The tetraploid leaves had larger stomata that were distributed at a lower density than those of the original diploid leaves. In the rooting culture, all tetraploids had much shorter root lengths than had the original diploids. Under rooting culture, tetraploid shoots of 'Gloire' and 'St. George' were shorter than those of diploids, but tetraploids of '3309' were not. In the acclimating stage in this experiment, the tetraptoids, also had shorter shoots, internodes and roots than had the original diploid plants. In the greenhouse experiment, shoot of tetraploid rootstocks, likewise, made poorer growth than did those of the diploids, but they tended to have thicker stem diameters and the specific leaf weights (leaf dry weight/leaf area). The thicker and shorter roots of the tetraploid rootstocks made their root system more compact than the diploids.