PJB-2018-1674
Effects of biochar amendment, CO2 elevation and drought on leaf gas exchange, biomass production and water use efficiency in maize
Fang Wang, Yuexian Liu, Xiangnan Li and Fulai Liu
Abstract
The effects of biochar amendment, CO2 concentration ([CO2]), drought and their interactions on the growth and physiology of maize were investigated. Maize was grown in pots with soil treated with (2%, w/w) or without biochar in one greenhouse chamber at a [CO2] of 400 mol l-1, and in a second chamber at a [CO2] of 800 mol l-1. At 19 days after planting, the plants were subjected to one of two watering regimes for one week, each plant either being well-watered or being drought-stressed by withholding irrigation. Before starting drought treatment, biochar amendment increased root dry biomass (RDM) and the root to shoot ratio (RSR), while CO2 elevation increased leaf area (LA) and specific leaf area (SLA) but decreased the chlorophyll content index (CCI) and stomatal conductance (gs). After drought, elevated [CO2] increased RDM, RSR, LA, SLA and photosynthetic rate (An), but decreased root water potential (Yr). A clear tendency of increasing water use efficiency (WUE) was noticed in maize grown under elevated [CO2] (P =0.080). Biochar amendment reduced evapotranspiration (ET). Drought decreased shoot dry biomass, total dry biomass, LA, An, gs, Yr and ET, but increased intrinsic WUE. It was concluded that elevated [CO2] enhanced maize growth and WUE, and biochar amendment tended to ameliorate some negative effects of drought stress on both growth and physiology under both ambient and elevated [CO2].
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