Potato and Tuber Crops

Flowering

• The flowering in potato depends on species, cultivar and environmental conditions.
• In general, Solanum tuberosum ssp. andigena flowers more frequently under short photoperiodic conditions than Solanum tuberosum. It is known that photoperiods of 18-19 hours are optimal for maximizing flowering and berry set.
• Subramanyam et al. (1972) reported that hybridization between the genotypes flowenng under short day conditions is possible in the plains. However, most of the genotypes do not flower under short photoperiodic conditions. This constitutes the major limiting factor in the success of TPS production in the plains. Therefore, efforts are to be made to overcome this limitation by inducing flowering in the genotypes, which normally do not flower under short photoperiod.

Induction of Flowering

• Pushkarnath and Chauhan (1964, 1967) overcome this difficulty by using hormones.
• The application of gibberllic acid (GA3, 50 ppm) on young leaves, when floral initials had just formed, resulted in flower induction in the shy flowering varieties.
• They observed that in these varieties a long photoperiod alone was not enough to bring about the synthesis of flowering hormones to a sufficient level to enable it to activate floral primordial.
• Gopal and Rana (1988), and Singh and Singh (1990) used 4-5 hours of additional illumination of about 200 lux from incandescent bulbs in continuation of natural day light.
• The genotypes showed differential response to various treatments.
• The growth regulators and prolonged day length alone were only partially successful in inducing flowering.
• The combined use of growth regulators and extra illumination was the most effective treatment. Such induced flowers could be successfully used in hybridization (Singh and Singh, 1090).
• Khan et al., (1993) reported that extra illumination provided for i6-18 hours by a 250 w high pressure sodium vapour loam and a single spray of GA (50 ppm) ÷ IBA (10 ppm) + kinetin (2 ppm) at bud initiation stage induced full inflorescence elongation, bud enlargement and finally bud opening.
• GA3 sprayed @ 75 ppm at 40 days after planting was also effective in flower induction (Lallan Singh, 1993).