Effects of growth hormones and maturity of the fruits on the callus culture of guava (Psidium guajava) fruits using response surface methodology

Guava, a tropical fruit, is valued for its aroma and is used in many fruit products. Earlier work from this laboratory has shown that the expression of the flavour as a secondary metabolite through tissue culture in vitro is possible. In the present study an attempt has been made to maximise the callus culture growth through optimisation of the hormonal combinations of indole acetic acid (IAA), 2,4‐dichlorophenoxy acetic acid (2,4D) and kinetin (Kn). The effect of using fruits of different maturity was also assessed. The study of the complex interactions of the growth hormones and the identifications of the optimal hormonal levels have been carried out using appropriate design of experiments which are specially framed for such purposes. Simplex optimisation techniques were used to obtain the optimum levels of these hormones for highest relative growth in the experimental region. The results indicate that callus culturing with fruits before reaching climacteric with MS medium supplemented with 0.01 mg litre−1 of IAA and 2,4D and 2.87 mg litre−1 of Kn results in a high relative growth of 8.97 for the callus.