Tratamentos pré-germinativos e substratos na emergência de sementes e qualidade de mudas de pinhão manso (Jatropha curcas L.)

Abstract

The physic nut can be propagated asexually or sexually. Using cuttings have been earlier yield and more fidelity characteristics of the parent plant. However, there is less initial vegetative growth. The seeds from the plants have increased genetic variability, are more vigorous and begin production later. To get quality changes, the substrate is an important factor. With that the objective was to taste pre-germinated treatments and different substrate on seeds emergence and quality physic nut seedlings. The experimental design was completely randomized, in factorial scheme 6 x 3 (pre-germinated treatments x substrate), 18 treatments and 4 repetition, 8 seeds to each repetition. It was evaluated six pre-germination treatments: T1: witness (without treatments); T2: water immersion for 12 hours; T3: water immersion for 24 hours; T4: mechanical scarification; T5: mechanical scarification + water immersion for 12 hours; T6: mechanical scarification + water immersion for 24 hours, using as substrate: commercial, expanded vermiculite and sand washed. The mechanical scarification was realized opposite the micropyle using sandpaper n. 60. After the pre-germination treatments, the seeds were emergence in plastic cups (200mL) with substrates. We evaluated the characteristics: percentage, beginning and emergence speed index, mean length of plant, diameter of plant stem, SPAD index, fresh and dry shoot and root. The results showed that in seeds of Jatropha do not need pre-germinative treatments; and the use of commercial substrate showed seedling development.