Harvest stages and pulsing in ornamental sunflower ‘Sunbright Supreme’

Abstract

The use of ornamental sunflower as a cut flower has been increasing due to the advent of new cultivars and the demand of the flowergrowing market for new products. However, there are few studies related to postharvest of this species. The objective of this research was to evaluate the water balance and durability of ‘Sunbright Supreme’ sunflower collected at three different harvest stages and submitted or not to a pulsing with sucrose. The flower stalks were collected fully open, at an intermediate opening stage and also closed; they were then standardized at 50 cm and stored in water or 4% sucrose solution during 24 hours. After this period, stalks were maintained in sealed bottles containing 500 mL of water. Fresh matter, water consumption, flower opening, complete durability and visual quality of stems were evaluated every three days, considering a rating scale of color, turgescence and stalk bending. Rates of absorption and transpiration were calculated considering the fresh matter and variation in water volume. There was an increase in fresh matter and high water consumption in inflorescences until the seventh day; after this period, there was a reduction in weight and increased transpiration rates. Stems collected closed, closed with pulsing and at an intermediate stage treated with pulsing were maintained in commercial quality about four days longer than the open harvested (with and without pulsing) and intermediate without pulsing. Sucrose pulsing leads to flower opening of stalks collected at all harvest stages. The positive water balance was observed until the seventh day and contributes to the maintenance of commercial quality in ornamental sunflower. The early harvest of ornamental sunflower ‘Sunbright Supreme’ is recommended, besides the application of 4% sucrose pulsing.