Emergência de plântulas e crescimento inicial de mudas de Hancornia speciosa Gomes em diferentes substratos, disponibilidades hídricas e níveis de luz

Abstract

Mangaba fruit (Hancornia speciosa) is a tropical fruit with economic promises for national fruit cultivation due to the high protein content of its fruits, that are very appreciated for in natura consumption and for production of candy, juices and ice creams. Although, the information about the seed germination and seedling production of this specie is still incipient. This way, this work aimed to evaluate substrates, water availabilities and light levels that are suitable to emergence and production of mangaba fruit seedlings. In the first experiment, seeds were deposited in tubes with the substrates: natural soil of the Dourados-MS region (Distroferric Red Latossol – L); Latossol + sand (L+ A) 1:1 proportion (v:v); Latossol + Bioplant® (L+B) 1:1 proportion; Latossol + Sand + broiler litter (L+A+C1) 2:2:1 proportion (v:v:v); and Latossol + Sand + broiler litter (L+A+C2) 2:4:1 proportion, associated to 25, 50, 75 and 100% of water retention capacity (CRA). In the second experiment, seeds were deposited in polyethylene sac with substrates L, L+A and L+B and they were kept in greenhouse with 30 and 70% of shading and at full sun. For evaluation of seedling emergence, in both experiments, percentage, emergence speed index and mean emergence time were determined. Seedlings were evaluated on 35, 70, 105 and 140 days after emergence (DAE) by surviving, number of leaves, height, average length of roots, stem diameter, chlorophyll index, leaf area, dry weight of aerial part and of roots, Dickson quality index, photosynthesis, transpiration and stomatal conductance. In the first experiment, the activities of superoxide dismutase, peroxidase and catalase enzymes in aerial part and in roots of seedlings were also evaluated. We used a completely randomized design with four replications of 25 seeds. The data were subjected to analysis of variance (p<0.05) and in case of significance, the regression analysis (p <0.05) in the first experiment and Tukey's test (p<0.05), second experiment. L+A, L+B and L substrates are recommended for seedling emergence and initial growth of mangaba fruit seedlings in 75 and 100% of water availability. Substrates that were compound with broiler litter and water availabilities of 25 and 50% damage growth and quality of seedlings. Mangaba seedlings develop at full sun or in 30 and 70% shading levels. However, transpiration and photosynthetic taxes and conductance of seedlings were higher in substrates under 70% of shading.