Enxertia e indução da floração com Paclobutrazol em golosa (Chrysom sapyllunuignolentum (Pierre) Baehnni)

Abstract

Accelerating the flowering and fruiting of species in degraded areas can make forest restoration more efficient. Grafting combined with plant growth regulators has the potential to enhance this process. This study evaluated the effectiveness of grafting and different graft protection techniques on the grafting success rate of Golosa seedlings (Chrysophyllum sanguinolentum) and the impact of paclobutrazol on grafted and non-grafted seedlings under different shading conditions. The experiment was conducted at the Federal University of Pará in two phases. The first phase, carried out between August and September 2023, involved grafting 160 seedlings distributed across four graft protection treatments: parafilm (T1), parafilm with kraft paper bag (T2), plastic bag (T3), and plastic bag with kraft paper bag (T4). A completely randomized block design was used, and the seedlings were kept in a greenhouse. Budding was evaluated at 20, 27, 34, 41, 48, and 56 days after grafting. Since normality and homogeneity assumptions were not met, the non-parametric Kruskal-Wallis test (p < 0.05) was applied. The second phase, conducted between June and December 2024, evaluated stem diameter, height, number of leaves, and chlorophyll index, considering grafting, shading, and paclobutrazol application as factors. A completely randomized design was used, with 56 seedlings divided into grafted (28) and non-grafted (28) groups, subjected to two shading levels (full sun and 50% shade) and two paclobutrazol treatments: application of 2 ml diluted in 250 ml of water and a control without application. Measurements were taken at 0, 30, 60, 90, 120, 150, and 180 days after PBZ application. Data analysis was performed using R Studio software, applying Generalized Linear Models (GLM). The results showed significant differences between graft protection treatments. T2 (parafilm with kraft paper bag) had the highest grafting success rate (27.5%), followed by T4 (12.5%), while T1 had 10%, and T3 showed no budding. Regarding shading, plants under 50% shade exhibited greater stem diameter growth (2.36%), a higher number of leaves (53), and a higher chlorophyll index (34.2 g). Height growth was also greater under shade but was not statistically significant. Non-grafted plants had a higher number of leaves (64), while grafted plants had the highest chlorophyll index (30.7 g). PBZ reduced the average number of leaves (42) and stem diameter growth (1.99%) but did not significantly affect height or the chlorophyll index. It is concluded that grafting is an effective asexual reproduction technique for C. sanguinolentum, and graft protection with parafilm and a kraft paper bag improves grafting success. Additionally, grafting may accelerate flowering and fruiting, but this hypothesis requires long-term monitoring. PBZ proved to be phytotoxic, reducing growth and causing total leaf loss.