Ozone-induced reduction in rice yield is closely related to the response of spikelet density under ozone stress.

Six modern rice cultivars, including three indica and three japonica cultivars were exposed to 100 ppb ozone (8 h per day) and control conditions throughout cropping season in 2016 to 2017 at Yangzhou, China. Ozone decreased plant height and inhibited tillering development as well as panicle number per plant of all cultivars, but had no effect on the productive tiller ratio. Ozone significantly decreased spikelet number per panicle, spikelet number per plant, fully-filled grain percentage and fully-filled grain weight, resulting in yield decrease by 39.

[Effects of ozone stress on amylose content and starch RVA profile in grains located at diffe-rent positions on a panicle].

The increase of ground-level ozone concentration significantly reduces rice yield, but its effect on grain quality in association with the positions on a panicle was largely unknown. The effects of ozone stress on amylose content and RVA profile of rice grains located at different positions of panicles were studied by using a sunlit gas fumigation platform. Eight varieties representing different types of rice were fumigated under ambient (9 nL·L) or elevated ozone (100 nL·L) concentrations from transplanting until maturity.