Methane emissions from reproductive organs of pea plants exposed to multiple abiotic factors

Abstract

Environmental stressors increase methane (CH 4) emissions from plants. Few studies have investigated the interactive effects of multiple abiotic factors on CH 4 emissions from plant vegetative organs and almost none from reproductive organs. We examined the combined effects of temperature, ultraviolet-B radiation, and watering regime on aerobic CH 4 emissions from plant reproductive parts. Pea (Pisum sativum L. cv. 237J Sundance) plants were grown under two temperature regimes (22/18°C and 28/24°C; 16 h light/8 h dark), two levels of UVB radiation (0 and 5 kJ m-2 day-1), and two watering regimes (field capacity and wilting point) in controlled-environment growth chambers for over a month, after one week of initial growth under 22/18 o C. Then, CH 4 emissions were measured from fully-opened flowers and pods (1-, 5-, and 10-day-old). Higher temperatures decreased flower dry mass, but significantly increased CH 4 emissions from flowers. Other individual environmental factors did not affect flower and pod dry mass or CH 4 emission. In some cases, however, interactions between or among factors significantly affected pod dry mass and CH 4 emissions from flowers and pods, suggesting the synergistic effects of environmental factors on plant-derived CH 4. In conclusion, stress factors increased flower and pod CH 4 emissions, which had inverse relationships with dry mass of reproductive organs.