Nitric Oxide Effects on Photosynthetic Rate, Growth, and Antioxidant Activity in Tomato

Nitric oxide has recently been recognized as a new growth regulator in plants. Its effects on plant functions are not clear. A study was conducted to investigate the growth-promoting effects of nitric oxide in Solanum lycopersicum L., cv. K-21, under net house conditions. Surface-sterilized seeds were soaked for 8 hours in 10−6, 10−5, or 10−4 M sodium nitroprusside (SNP), a nitric oxide donor. Resulting plants were sampled at 45 and 60 days after sowing to assess effects on growth as well as photosynthetic and biochemical parameters. The 10−5 M SNP was best followed by the 10−4 and 10−6 M concentrations. The favorable effect was attributed to NO-induced biosynthesis of proline and a rise in activity of the antioxidant system.