Reações ao estresse pós-colheita em inflorescências de bastão-do-imperador

Abstract

Flowers need proper management for post-harvest practices in order to maintain quality, allowing them to have a satisfactory shelf life. For this, techniques are developed to delay the senescence of flower stems. To increase the durability of flower stems, preservative solutions are used, in addition to adequate hydration, control of the storage environment, in addition to the use of coating technologies. Thus, the objective was to evaluate the quality and physiology of post-harvest Etlingera elatior stems resulting from pulsing treatments at different concentrations, dry conditioning and storage temperatures. To carry out the experiments, torch ginger stems were harvested, sanitized and standardized. Pulsing was performed by placing the stems in a sucrose solution at concentrations of 0%; 15%; 20%; 25%. Regarding the conditioning test, the stems were kept dry for 0h; 3h; 6h; 12h; 24h, after this period, transferred to recipients with pulsing solution for 24h and, later, kept in water. Finally, the temperature test consisted of storing the stems at temperatures of 8 ºC; 12 °C; 16 °C; 20 °C and 24 °C. Every 3 days, visual quality, absorption rates and water contents, fresh and dry masses and color parameters were evaluated. For the biochemical evaluations, the content of carotenoids and anthocyanin, hydrogen peroxide (H2O2) and lipid peroxidation, enzymes of the antioxidant system and protein and sugar reserves were analyzed. Pulsing with 20% and 25% sucrose accelerated the emergence of true flowers, increased the absorption rate and fresh mass of the stems, in addition to having observed an increase in lipid peroxidation and in protein and sugar reserves. Torch ginger stems did not show expression of SOD and CAT enzymes. Among the concentrations tested, pulsing with 15% sucrose is recommended as it favored visual quality until the 9th day post-harvest. Dry conditioning for a period longer than 12 hours is not recommended as it resulted in a loss of quality and durability, in addition to advancing the senescence process for the torch ginger stems, since after this period a reduction in the absorption and breakage rate is evidenced of pigments. In addition, an increase in H2O2 and lipid peroxidation, as well as in the consumption of sugar and protein reserves, was evidenced. The recommendation is that the stems are immediately hydrated after harvesting. Stems stored at 8 ºC maintained the reserves longer and also induced the production of reactive oxygen species, however, they caused injuries by mischaracterizing the stems and reducing quality. Stems stored at 12 ºC absorbed more water when compared to those stored at 8 ºC, maintaining quality for longer. Higher storage temperatures accelerated the appearance of true flowers, increased the consumption of macromolecules, reducing the durability of the stems. The storage of torch ginger stems should be carried out at temperatures between 12 ºC and 16 ºC since they have a higher quality for commercialization for a longer time. Through the analyzes carried out, it was possible to evidence the effect of treatments and storage conditions on the physiological and biochemical aspects of torch ginger.