Evaluating Impacts of Water Stress on Rice Biomass Composition, Feedstock Availability and Bioenergy Production Potential

Abstract

Bioenergy production from rice biomass feedstock is considered as one of the potential clean energy resources and several small biomass−based powerplants has been established in rice growing areas in addition to use of rice biomass as supplementary feedstock. However, rice biomass production is significantly affected due to various factors including climatic factors, shift in rice production systems, choice of cultivars at large scale cultivation, variability in biomass production potential and water stress occurrence which results in declined biomass availability and quality. Water stress is a critical aspect which influence the rice biomass productivity and quality the most, therefore, the impacts of water stress were evaluated on six Thai rice cultivars for their biomass quality, production, and bioenergy potential. Rice cultivars were experimented in field under well−watered (WW) and water stress (WS) treatments. Data for days to maturity of rice cultivars and rice biomass contributing parameters including stem height, stem numbers and biomass yield was collected at harvest. Proximate and lignocellulosic contents of rice biomass samples were determined for biomass composition analysis. Results showed that water stress negatively affected the crop production performance which resulted in 11−41% decline in biomass yield. Cultivar stability assessment for stable biomass production indicated that cultivars Hom Pathum and Dum Ja demonstrated comparatively smaller reductions by 11% in their biomass yield production under water stress. Statistical comparison for proximate contents showed significant negative affect which influenced biomass quality as the ash contents of cultivars Hom Chan, Dum Ja and RD−15 were raised by 4−29% under water stress. Lignocellulosic evaluation revealed, an increase in lignin contents of cultivars Hom Nang Kaew, Hom Pathum, Dum Ja and RD−15 ranging from 7 to 39%. Decline in biomass production under water stress caused a 10−42% reduction in bioenergy potential of Thai rice cultivars. Results demonstrated that cultivation of stress prone rice cultivars or farmer’s choice to grow specific cultivars and incidence of water stress during rice crop growth period will reduce biomass production potential, biomass feedstock availability to biomass−based powerplants and will affect powerplant’s energy conversion efficiency leading to declined bioenergy production.