70 Papaya
untreated control with 48 h water soaking (Dhinesh Babu et al. 2010). Field germi-
nation of papaya seeds can be greatly improved by soaking them before planting in
an aqueous solution of potassium nitrate (KNO 3 ). Germination percentage of both
fresh and dried seeds can be increased with this method. The time to germina-
tion after the soaking treatment is reduced, and maximum germination is achieved
sooner when untreated seeds are sown. Seeds soaked in KNO 3 solution produce
seedlings that are initially more vigorous than seedlings from the untreated seeds
(Yogananda et al. 2004).
FIGURE 5.1 (See colour insert.) (a) Multiple shoot induction on MS medium with BAP
(5 μM) + NAA (0.05 μM), (b) elongation on half MS with 1.5 μM of GA 3 ; (b1) stunted shoot
before GA 3 treatment, (b2) elongated shoot after GA 3 treatment, (c) rooting of in vitro regen-
erated shoots in half MS with 2.5 μM of IBA, (d) plant with well-developed root system ready
for hardening, (e) plant acclimatised to greenhouse conditions. (Adapted from Anandan, R,
S. Thirugnanakumar, D. Sudhakar and P. Balasubramanian, 2011, Journal of Agriculture
Technology, 7(5): 1339 – 48.)