Assessment of photosynthetic and photothermal responses to water limitation in three sugarcane (Saccharum spp.) genotypes using the photoacoustic technique

Abstract Sugarcane ( Saccharum spp. ) is a crop of considerable economic importance in tropical and subtropical regions, including 51 municipalities in six departments of Colombia. However, the productivity of this crop is hindered by water stress, which contributes to its high mortality rate. To assess the behavior, resistance, and adaptability of three sugarcane varieties (CC 05–430, CC 11–600, and CC 01–1940) in response to water deficit, a phenotyping study was conducted using the photoacoustic (PA) technique. This study was based on the analysis of certain morphoanatomical and physiological traits, including the examination of a possible pattern in photosynthetic activity according to each genotype as a discriminant method. To this end, the PA technique was employed, a non-invasive and cost-effective method that enables a measure of photosynthetic activity, through oxygen evolution rate determination via photobaric amplitude rate (PBAR), for the diagnosis of water stress, and compared with the fluorescence spectroscopy method. The findings indicate that, in general, the PBAR changed in the three varieties during the drought period. However, the CC 05–430 variety demonstrated a more optimal physiological balance under adequate irrigation conditions, suggesting a higher degree of adaptation to water-limited stress scenarios. Additionally, the thermal diffusivity, measured using the aforementioned technique, exhibited a change in response to drought conditions, suggesting its potential as a diagnostic tool for differentiating between distinct genotypes in terms of their water regulation capacity.