Methane emissions from rice fields: Effect of plant height among several rice cultivars

The effect of rice cultivar and plant height on methane (CH4) emission from rice fields was studied from data of 8-year field experiments. Field exper iments were conducted from 1989 to 1996 at the Texas A & M University Agric ultural Research and Extension Center near Beaumont, Texas. Eleven rice cul tivars and three soil types were involved. The results of this study showed the following: 1) Rice cultivar choice slightly influenced the day-to-day seasonal pattern of methane emission, but it had a significant effect on th e seasonal total methane emission. The average seasonal methane emission is 22.8 g CH4 m(-2) for high emitting cultivars (Mars and Della), ranging fro m 8.0 to 41.0 g CH4 m(-2) and 17.7 g CH4 m(-2) for low-emitting cultivars ( Lemont, Labelle, Lebonnet, Dawn, Katy, IR 36, Cypress, and Jasmine), rangin g from 1.7 to 28.4 g CH4 m(-2). 2) Seasonal methane emission has a positive linear correlation with postheading rice plant height. The correlation coe fficient r(2) is 0.736 (n = 24, and p < 0.05). In this paper we suggest tha t plant height may be a good criteria in choosing cultivars for mitigation of methane emission. More importantly, it provides a potential method for e stimating methane emission from regional or global rice paddies as plant he ight can be evaluated by remotely sensed imagery.