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

Environmental stressors increase methane (CH₄) emissions from plants. Few studies have investigated the interactive effects of multiple abiotic factors on CH₄ 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 CH₄ 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 ^oC. Then, CH₄ emissions were measured from fully-opened flowers and pods (1-, 5-, and 10-day-old). Higher temperatures decreased flower dry mass, but significantly increased CH₄ emissions from flowers. Other individual environmental factors did not affect flower and pod dry mass or CH₄ emission. In some cases, however, interactions between or among factors significantly affected pod dry mass and CH₄ emissions from flowers and pods, suggesting the synergistic effects of environmental factors on plant-derived CH₄. In conclusion, stress factors increased flower and pod CH₄ emissions, which had inverse relationships with dry mass of reproductive organs.