Growth and photosynthetic capability of momordica grosvenori plantlets grown photoautotrophically in response to light intensity

Momordica grosvenori plantlets were cultured in vitro for 26 d on sucrose- and hormone-free Murashige and Skoog (MS) medium with four levels of photosynthetic photon flux density (PPFD), namely 25, 50, 100, or 200 mu mol.m(-2).s(-2), and a CO2 concentration of 1000 mu mol.mol(-1) in the culture room [i.e., photoautotrophic micropropagation (PA) treatments]. The control treatment was a photomixotrophic culture using MS medium containing sucrose and NAA with a CO2 concentration of 400 mu mol-mol(-1) in the culture room and a PPFD of 25 mu mol.m(-2)-s(-1). Based on the results, a second experiment was conducted to investigate the effects of alpha-naphthaleneacetic acid (NAA) and sucrose on callus formation. For this, plantlets were grown in the absence and presence of either NAA or sucrose. Compared with the control, the PA plantlet had a well-developed rooting system, better shoot, greater chlorophyll content, and higher electron transport rate and the ex vitro survival percentage was increased by 31%. Both sucrose and NAA stimulated callus formation on the shoot bases of control plantlets, whereas calluses did not form on the plantlets grown in sucrose- and hormone-free medium. The stronger light intensities increased the fresh and dry weight of plantlets. A PPFD of 100 mu mol.m(-2).s(-1) was more suitable for the growth of M. grosvenori plantlets. Therefore, photoautotrophic plantlets grown at high light intensities would be better suited to the intense irradiance found in sunlight.