Water productivity and canopy thermal response of pearl millet subjected to different irrigation levels

Abstract

Pearl millet is a valuable alternative crop to biomass and forage production. However, water productivity (WP) in this crop under limited water conditions remains unclear in literature. In addition, rapid and reliable techniques to detect water stress spatial variability under field conditions are necessary. The objective of this study was to verify the yield and canopy thermal responses of pearl millet subjected to different water replacement levels (WRL). A rain shelter experiment was conducted using a randomized block design with four replications at University of São Paulo in Piracicaba, São Paulo, Brazil. Pearl millet cultivar BRS-1501 was subjected to four WRL treatments: WRL40, WRL70, WRL100 and WRL130. The reference WRL treatment, WRL100, was irrigated to maintain soil moisture at field capacity level, whereas the other treatments were a fraction of the irrigation depth applied in WRL100 treatment. The highest dry biomass yield obtained was 12.1 Mg ha−1 under WRL130 treatment, and this value diminished as WRL decreased. On the contrary, WP increased as the WRL decreased, recording the highest WP in WRL40 (9.0 kg m−3). Pear millet canopy showed different thermal responses as a function of WRL treatments imposed, being an alternative tool to detect water stress zones in the field by remote sensing technologies.