A growth and biochemistry of ten high yielding genotypes of Pakistani rice (Oryza sativa L.) at maturity under elevated tropospheric ozone.

Experimental studies were conducted to estimate the possible damage caused to ten rice (Oryza sativa L.) genotypes of Pakistan by tropospheric ozone. The experimental site is located at 31.4504° N and 73.1350° E, at an altitude of 184 m.a.s level with an average annual rainfall of 784 mm. A suitable and agile method was adopted to assess tolerance and susceptibility in rice genotypes at an early growth stage. Genotype Injury response, growth and biochemical parameters were measured to estimate possible effects of ozone, which was subsequently proclaimed as a criterion for ozone tolerance. Rice genotypes were subjected to ozone concentrations of 70 pbb (Current ambient) and 120 pbb (expected in near future) under a polytunnel. The findings indicated that ozone, an atmospheric pollutant, substantially harmed crop growth and metabolism, as well as inflicted a specific type of foliar injury that caused early leaf senescence. Rice genotype IR-9 followed by Punjab-Basmati and Ksk-434 appeared to be the most susceptible, whereas Basmati-515 followed by Basmati 2000 and super-Basmati were found to be Ozone-tolerant. Plant genotypes grown under elevated ozone showed 13.45% and 11.35% reduction in total root and shoot dry weight, and 25.54% and 6.6% decrease in plant leaf area and plant total length respectively compared to the control group. A significant interaction between treatment × chemical components and growth parameters was also found. The Present study confirms a direct relationship between visual response and growth as well as biochemical parameters. Declared results were statistically analyzed by using analysis of variance at confidence level of p < 0.05.