Escarificação e uso de GA3 na germinação de estrelícia

Abstract

The propagation of strelitzia (Strelitzia reginae) is mainly done by splitting clumps or by seeds, but these have dormancy and low germination rates. Thus, it aims to improve the in vitro and ex vitro germination processes for strelitzia, using chemical and physical scarification, and gibberellic acid (GA3) for break the seed dormancy. The seeds were submitted to chemical scarification in sulfuric acid at different immersion times (10, 20, 30, 40, 50 and 60 minutes) and physical scarification using sandpaper, for addition to the control without scarification. The seeds used on the in vitro condition were disinfected and inoculated in MS medium supplemented with 0, 20, 40 and 80 μM of GA3. For the ex vitro experiment, the seeds were planted in plastic tubes with commercial substrate Tropstrato®, irrigated with 0, 25, 50 and 100 μM of GA3 solution and analyzes every 15 days. The germination percentage of the in vitro experiment was evaluated after 15, 30, 45 and 60 days, and ex vitro, after 30, 45 and 60 days. Agronomic analyzes carried out, at the 60th day, evaluated of shoot length (cm), root (cm), number of leaves and survival (%) were collected. The in vitro results demonstrated that the greatest germination percentage occurred when the seeds were scarified with sulfuric acid for 30 and 40 minutes, regardless of GA3 addition in the medium. At 60 days in vitro cultivation, the physical scarification and the scarification times in sulfuric acid (20, 30 and 40 minutes) of the seeds promoted greater length of the aerial part the root and the highest averages of the number of leaves. The highest seedling survival was obtained from seeds immersed for 30 minutes (86.66%) and 40 minutes (80%) in sulfuric acid without the addition of GA3. After 30 days of in vitro culture, germination stabilized. After 30 days of in vitro cultivation, germination stabilized. For in vitro germination, scarifying the seeds for 30 minutes is recommended. On the other hand, the ex vitro results showed that a higher percentage of germination was obtained in scarified and irrigated seeds with 100 μM GA3 (62.22%). After 60 days of ex vitro cultivation, was observed greater germination (66.66%). Shoot length and number of leaves values were observed in non-scarified and treated seed with 100 μM GA3. The roots presented greater growth when there was not used any scarification treatment or in the 10 minutes seed scarification. Seedling survival was greater when there was no scarification. Thus, it is recommended to in vitro germination of strelitzia scarifying the seeds in sulfuric acid for 20 minutes. For ex vitro germination only 100 μM GA3 irrigation is recommended.