INTEGRATION OF SALICYLIC ACID IN IN VITRO ROOTING MEDIUM IMPROVES PHOTOSYNTHESIS AND GROWTH DURING ACCLIMATIZATION OF PHILODENDRON BIPINNATIFIDUM SCHOTT EX ENDL. PLANTLETS

Salicylic acid (SA) influences plant physiological processes and induces tolerance to several stresses. Such stresses are imposed on micropropagated plants during the acclimatization stage, due to their underdeveloped photosynthetic apparatus. The aim of the study was to improve the growth and acclimatization of P. bipinnatifidum by the application of SA during in vitro rooting. Axillary shoots were rooted on MS medium supplemented with alpha-naphthaleneacetic acid (1 mg l(-1)) and different concentrations (0, 5, 10, 25, and 50 mg l(-1)) of SA for 6 weeks. The plants were then acclimatized in a sterile mixture of peat moss and perlite (1 : 1; v/v) for 30 days in a growth chamber. SA application resulted in higher levels of stomatal conductance, transpiration, and CO2 assimilation. Biomass measurements and growth indices (leaf weight ratio, stem weight ratio, root weight ratio, and specific leaf area ratio) were highest in plantlets supplemented with 10 mg l(-1) SA. Based on these findings, the application of SA is recommended to improve the growth and acclimatization of P. bipinnatifidum.