Response to water stress and defoliation of the forage legume Calopogonium mucunoides Desv according to area of origin

Abstract

The main limiting resource in drought is water. Consequently, this resource along with other edaphoclimatic factors affect various aspects of growth and development of individuals. In this study, were evaluated drought tolerance and compensatory growth of Calopogonium mucunoides Desv from two different provenances; subjected to defoliation and water deficit. In controlled greenhouse conditions, an experiment was carried out with a factorial arrangement of eight treatment combinations with three replicates each. Individuals of C. muconoides were subjected to two levels of defoliation: defoliated plants every fifteen days vs non-defoliated plants; two levels of water regime: plants watered every two days vs plant watered every seven days, using plants from: Muy Muy and Rivas. The variables evaluated were aerial biomass, root biomass, total biomass, relative growth rate, water potential and stomatal conductance. A linear mixed model adjusted by restricted maximum likelihood was used. All statistical analyzes were performed with the R statistical software. The results show a differentiated and complex response in the biomass production and physiological characteristics of the C. mucunoides provenances to the combined effect of defoliation and the water regime. The defoliated plants and plants from Muy Muy presented a higher compensatory growth compared to the Rivas plants. There was a decrease in the water potential and stomatal conductance in defoliated plants and with water stress. Under the study conditions, the C. mucunoides species is tolerant to defoliation and water stress.