Estratégias estruturais, fisiológicas e bioquímicas associadas à tolerância ao déficit hídrico em genótipos de maracujazeiros (Passiflora edulis Sims)

Abstract

Water deficit constitutes one of the main limiting factors for growth, productivity, and sustainability of passion fruit cultivation (Passiflora edulis Sims), especially in the context of increasing rainfall irregularity associated with climate change. Plant responses to water limitation involve integrated structural, physiological, and biochemical adjustments, whose magnitude and efficiency are strongly genotype-dependent. In this context, the present thesis aimed to evaluate, in an integrated manner, the adaptive strategies associated with drought tolerance in genotypes of Passiflora edulis. Two complementary studies were conducted under greenhouse conditions using the genotypes IAC 1013, IAC 273, IAC 277, and BRS Rubi do Cerrado, cultivated under full irrigation and water deficit conditions. At the foliar level, water deficit reduced gas exchange and leaf water potential without compromising the photochemical efficiency of photosystem II, indicating maintenance of photosynthetic functional integrity. Proline and starch accumulation were observed, along with modulation of soluble sugars and anatomical adjustments associated with water conservation and hydraulic safety. In the root system, water deficit promoted contrasting anatomical and architectural modifications among genotypes, including adjustments in the thickness of outer tissues, cortical reorganization, modulation of the vascular system, and changes in root growth angle. The Relative Distance Plasticity Index (RDPI) revealed high anatomical and architectural plasticity in IAC 277, whereas IAC 1013 exhibited a more conservative pattern associated with greater structural stability. IAC 273 was characterized by the maintenance of vascular components under water limitation, and Rubi displayed an intermediate strategy, combining plasticity and structural stability. Overall, the results demonstrate that drought tolerance in Passiflora edulis is supported by the coordination between foliar metabolic adjustments and structural reorganization of the root system, involving a balance between anatomical plasticity, hydraulic efficiency, and functional maintenance. These findings provide relevant insights for breeding programs and crop management strategies in environments with water limitation.