Effect of explant orientation on shoot regeneration in tomato (Lycopersicon esculentum)

Abstract

Effects of explant orientation on percent shoot regeneration in tomato (Lycopersicon esculentum M.) were studied using two commercially important cultivars, viz Hisar Arun and Hisar Lalit. The explant orientation affected shoot regeneration in both genotypes. Both cotyledon and leaf explants placed in abaxial (lower surface facing down) orientation produced higher percent regeneration and higher number of shoots per explant as compared to those placed in adaxial (upper surface facing down) orientation. In Hisar Arun, when cotyledon explants cultured in abaxial orientation on medium
containing zeatin 1.5 mg/l, maximum per cent shoot formation was 80.63% while in adaxial orientation it was decreased to 42.50%. Similar pattern of decrease in percent regeneration from 75.73% to 27.31%, on changing the orientation of cotyledon explants, was observed in cv. Hisar Lalit on medium containing BAP 1.5 mg/l. In leaf explants of cv. Hisar Arun, on medium supplemented with zeatin 1.5 mg/l, percent shoot regeneration reduced from 46.93% to 32.78% on changing the orientation from abaxial to adaxial. In cv. Hisar Lalit, per cent shoot regeneration was reduced to less than half (75.00% to 36.11%), on medium containing BAP 1.5 mg/l when the leaf explant were placed adaxially. The present study revealed that orientation of explant had significant effect on per cent regeneration.