Water availability moderates N2 fixation benefit from elevated [CO2]: A 2-year free-air CO2 enrichment study on lentil (Lens culinaris MEDIK.) in a water limited agroecosystem

Abstract

Increased biomass and yield of plants grown under elevated [CO2] often corresponds to decreased grain N concentration ([N]), diminishing nutritional quality of crops. Legumes through their symbiotic N2 fixation may be better able to maintain biomass [N] and grain [N] under elevated [CO2], provided N2 fixation is stimulated by elevated [CO2] in line with growth and yield. In Mediterranean-type agroecosystems, N2 fixation may be impaired by drought, and it is unclear whether elevated [CO2] stimulation of N2 fixation can overcome this impact in dry years. To address this question, we grew lentil under two [CO2] (ambient ~400 ppm and elevated ~550 ppm) levels in a free-air CO2 enrichment facilit..