Morphological, Physiological and Nutritional Effects of Irrigation Frequency on Macaúba Palm Seedlings

The commercial nurseries of macaúba palm (Acrocomia aculeata) have experienced excessive seedling mortality, which is possibly due to the lack of information about the proper growing practices. The goal of this study was to investigate the response of macaúba seedlings to water stress using different irrigation frequencies during the early seedling stage. The experiment was carried out in a macaúba palm nursery located in João Pinheiro, Minas Gerais, Brazil. The treatments started 30 days after sowing. At 90 days after sowing, the morphological (number of leaves, stem diameter, shoot length, root weight and the fresh and dry matter content of leaves, stem and roots), physiological (allocation of photosynthates) and chemical (nutrient content in the shoot) characteristics were evaluated. The results indicated that shoot height and stem diameter became smaller as the frequency of irrigation was reduced. However, the accumulation of fresh biomass in leaves and stems, and the leaf and root dry biomass became higher under the same condition. When water stress was induced in younger seedlings, the allocation of photosynthates occured more proportionally across all organs of the plants. The highest accumulation of K, S and Fe in the shoot were observed in plants that were exposed to water stress. N accumulation was higher in the aerial part of the seedlings as the irrigation frequency increased. However, the opposite behavior was observed for P, which accumulation was lowest in the control treatments.