2018 Volume 43 Issue 3 Pages 499-508
We studied differences on leaf physiological and allocational responses to drought in three fabaceous seedlings (Mimosa hostilis Benth., Mimosa verrucosa Benth. and Prosopis juliflora DC.). Two Mimosa species are native species and dominate in Caatinga in northeast Brazil. P. juliflora is introduced from Central and South America for timber. We compared performance of pot-grown seedlings between three different soil water conditions (control, medium drought treatment and severe drought treatment). Differences of the growth between two Mimosa species and P. juliflora closely related with their plasticity in water availabilities and biomass allocation under drought condition. Under severe drought condition, the height growth reduction rate relative to control in P. juliflora was lower than two Mimosa species, which showed limited growth. Improvement of leaf water availability (e.g. decreased leaf water potential at turgor loss point: Ψwtlp) by osmotic adjustment was highest in P. juliflora under severe drought condition. In addition, P. juliflora achieved high net assimilation rate (NAR) and high water use efficiency (WUE) by low leaf amount and high root biomass under drought condition. Overall, drought tolerance at seedling stage of P. juliflora is higher than two Mimosa species by having high osmotic adjustment and high plasticity of biomass allocation.
