Screening three cultivars of Vigna mungo L. against ozone by application of ethylenediurea (EDU)

Three Indian black gram cultivars (Vigna mungo L. cv. Barkha, Shekhar and TU-94-2) were grown at a tropical suburban site in Varanasi, India to evaluate the varietal differences in response to ambient O3 under field conditions using ethylenediurea (EDU). EDU (400 ppm) was given as soil drench at 10-day intervals during the growth period of the cultivars. O3 monitoring data clearly showed high concentrations with a mean value ranging between 41.3 and 59.9 ppb. EDU treatment caused significant increases in various growth parameters and total biomass accumulation in Barkha and Shekhar. EDU caused retention of more biomass in leaves during vegetative period and translocated more photosynthates towards reproductive parts, which resulted into yield enhancement. Weight of seeds plant−1 was higher by 36.4% and 35.6% in Barkha and Shekhar, respectively, treated with EDU compared to non-EDU-treated plants. However, TU-94-2 did not exhibit any significant difference in weight of seeds plant−1. Starch, total sugar, amino acids and K contents increased in seeds of EDU-treated plants leading to improvement in quality response index (QRI) of seeds. EDU helped in identifying the cultivar susceptibility to O3 stress and therefore is very useful as a monitoring tool to assess the impact of ambient O3 on plants under natural field conditions particularly in areas experiencing moderate concentrations of O3.