Nitrous oxide inhibits in vitro growth of multiple postharvest fungi

Nitrous oxide (N2O)was tested as a potential fungicidal or fungistatic compound. Twelve postharvest fungi were exposed to 10 to 80 kPa with 20 kPaO(2) in a static system at 20 degreesC. These fungi were divided into N2O high-, medium- and low-sensitive groups. Based on growth sensitivity, growth of high-sensitive fungi was completely inhibited, and that of medium-sensitive fungi up to 85%. With low-sensitive fungi, significant inhibition was achieved only when the fungi were exposed to N2O continuousIy for 6 days. Botrytis cinerea Pers.: Fr., Colletotrichum acutatum Simmonds, Monilinia fructicola (Winter) Honey, Penicillium expansum Link, Penicillium italicum Wehmer, Phytophthora citrophthora (R.E. Smith and E.H. Smith) Leonian and Rhizopus stolonifer (Ehrens.: Fr.) Vuillemin, were high-sensitive; Glomerella cingulata (Stoneman) Spaulding was medium-sensitive, and Alternaria alternata (Fr.) Keissler, Fusarium oxysporum Schlechtend1: Fr. f. sp.fragariae Winks and Williams, Fusarium oxysporum Schlechtend1: Fr. f. sp. lycopersici (Saccardo) Snyder and Hansen., and Geotrichum candidum Link., were low-sensitive fungi. Addition of up to 100 muL.L-1 C2H4 did not reduce inhibition caused by N2O. The inhibitory effect of N2O was considered to be due to biophysical properties similar to CO,, the competitive inhibition on C2H4 action, or the biosynthesis of methionine. These results indicate the potential of N2O to control some postharvest decay fungi.