Como a absorção foliar de orvalho afeta plantas jovens decíduas e sempre-verdes da vegetação sazonalmente seca brasileira?

• Ano de defesa: 2018
• Autor(a) principal: Holanda, Alexandre Emanuel Regis
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Absorção foliar de orvalho (AFO); Longevidade foliar; Resistência à seca; Taxa de crescimento relativo (TCR); Traçador apoplástico; Trocas gasosas; Vegetação sazonalmente seca brasileira (VSSB)
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/31950

Foliar absorption of dew (FAD) is an important alternative water acquisition mechanism for plants from Seasonally Dry Brazilian Vegetation (SDBV), including the caatinga vegetation of Brazilian semiarid. However, new research describing the anatomical pathways involved in this mechanism and the effects of dew on water status, gas exchange, leaf life span, growth and plant morphology can increase knowledge about AFO in SDBV. We propose two hypotheses: (1) the FAD increases leaf water status, gas exchange and the leaf life span of deciduous more than evergreen species; (2) the FAD favors growth, leaf maintenance and resistance of young plants to drought. Therefore, we submitted deciduous and evergreen young plants to treatments of irrigation, simulation of long and short duration dew and water restriction. The work was conducted in two lines: (1) verification of FAD routes and their contribution in the ecophysiological performance of leaves through anatomical analysis, apoplastic tracer solution applications and measures of water potential, gas exchange and leaf life span; (2) investigation of the contribution of FAD in the carbon balance according to measurements of growth, leaf wilt stages, leaf maintenance and resistance to drought. We found out that early (Mimosa caesalpiniifolia) and late (Combretum leprosum and Libidibia ferrea) deciduous plants, as well as the evergreen species (Cynophalla flexuosa) were able to absorb water through their leaves by their cuticles and/or peltate trichomes. The FAD process depends on the longer leaf exposure to dew. Although all species have prolonged leaf life span upon dew, young plants of the evergreen species, C. flexuosa, have stomatal regulation close to strictly isohydric regulation and had higher leaf water status, gas exchange (gs and A), growth, survival, resistance to drought, leaf life span and the production of new leaves over time. Thus, FAD is relevant for the establishment of young plants with different phenophases in the SDBV.