Different levels of water deficit induces changes in growth pattern but not in chlorophyll fluorescence and water relations of Hancornia speciosa Gomes seedlings

Resumo

The tree Hancornia speciosa Gomes is commonly known in Brazil as “mangabeira”, the fruit of which has high nutritional value. The knowledge about its physiology is still scarce, mainly during the initial phase of development. Thus, the aim of the present study was to evaluate the effects of different water deficit levels on growth pattern, chlorophyll fluorescence and water relations in H.speciosa seedlings. A A factorial experimental design (water treatment x evaluation time) was used with four water treatments based on the field capacity (FC) (80%, 60%, 40% and 20%) with five replications. Plant height, number of leaves, stem diameter, dry biomass production and partitioning, quantum efficiency of photosystem II (PSII), water potential (Ψw), relative water content (RWC), carbohydrates, proteins and proline content were analyzed. Severe water stress (20% FC) led to a reduction in growth and altered the biomass partitioning pattern in the seedlings. However, water relations were not significantly affected, as the seedlings maintain high Ψw and RWC without significant increase in organic solutes content when cultivated in 20% FC. Moreover, the quantum efficiency of PSII was unaffected by the different water levels, suggesting a lack of photoinhibition due to water stress. The change in growth pattern, with an increase in root depth and reduction in shoot emission, seems to be the main strategy of the H. speciosa seedlings for the maintenance of tissue hydration throughout periods of water deficit.