Abstract

                                The present study aimed to assess the response of 15 rice cultivars exposedto elevated ozone stress. The plants were exposed to 100 ppb ozone (10:00–17:00 h) for 30 days at the reproductive stage. Elevated ozone significantlyalters the physiological, biochemical, growth and yield traits of all test ricecultivars. Elevated ozone exposure significantly decreased photosyntheticrate maximally in MDU5 (42.90%) and TRY(R)2 showed maximum reductionin stomatal conductance (42.39%) and chlorophyll content (41.22%). In termsof yield traits, a decrease in tiller number, number of effective tillers, numberof filled spikelets per panicle and 1000 grain weight over the control werealso observed. The multivariate analysis with a total variance of 58.86%categorized the 15 rice cultivars into ozone sensitive (TRY(R) 2, ASD16,ADT(R)45 and MDU5), moderately ozone sensitive (ASD18, ADT43, RiceMDU6, ADT36 and ADT37), moderately ozone tolerant (ADT(R)48 CO47 andRice CO51) and ozone tolerant (Rice TPS5, Anna(R)4 and PMK(R)3) under100 ppb ozone. The present results revealed that the ozone tolerant ricecultivars would be recommended to cultivate in the regions experiencinghigh ozone concentration.

Key words : Rice cultivars; Elevated ozone; Plant traits; Principle Component Analysis