Effect of Nutrient Media and Sucrose Concentration on Shoot Organogenesis in Tomato

The $F_1$ hybrid Red Coat is one of the most highly sought after cultivars of tomato in Australia and yields up to 7.5 $\cal{kg/plant}$. An experiment was conducted to de-termine the optimal strength and type of growth medium and sucrose concentration for shoot organogenesis of the Red Coat cultivar using cotyledonary explants. Two basal growth media, viz. MS and Gamborg' s $B_5$ at 0, 1/4, 1/2, full or double strength along with sucrose concentrations of 0, 0.5, 1.5, 3 or $5\%$, were evaluated using 25 replications. The main effects of treatment and their mutual interactions were evaluated for the proportion of explants that produced callus and/or shoots, number of shoots produced per explant, callus diameter and shoot height. The explants failed to produce shoots in the absence of mineral nutrient. Only a small proportion of the explants ($6\%$ with $B_5\;and\;3\%$ with MS) regenerated shoots in the absence of sucrose. Lower sucrose concentrations ($0.5-1.5\%$) along with full strength media were optimal for most of the traits studied. The $B_5$ medium outperformed MS medium for shoot organogenesis. For all the traits examined, significant differences in main effects (P < 0.05) and two-way interactions were detected, but no three-way interactions (medium type $\times$ medium concentration $\times$ sucrose concentration) were observed. Sucrose was found essential for the development of chlorophyll. Chlorophyll content increased with an increase in sucrose concentration up to $3\%$ and decreased at $5\%$ sucrose.