Safflower (carthamus tinctorius l., asteraceae) is an oilseed species with fast seed resource mobilization

Abstract

Safflower (Carthamus tinctorius L.) is a crop with wide commercial potential, due to the broad adaptability of cultivation and use conditions, but commercial initiatives are deficient. This scenario extends to academic research, which also focuses little on understanding the involved processes from the germination of its seeds to the correct management of adult plants. In this context, the current study seeks to identify the primary metabolites stored in the safflower seed and to evaluate how the mobilization of these reserves occurs during seed germination and seedling establishment. Safflower seeds of the cultivar S-351 produced in the experimental field of Universidade Federal de Jataí, from the second season of 2017/2018, were used. To obtain the seedlings, safflower seeds were sown in moistened sand with 60% retention capacity and kept at 25 °C. At 1, 2, 3, 4, 5, 8, 15 and 22 days after sowing, the seedlings were subjected to analysis of length and histological characterization of cotyledons, the latter of which also evaluated at 12 h after sowing. Biochemical (carbohydrate, protein, lipid and chlorophyll) and anatomical analyses were performed to assess reserve mobilization, both of which were evaluated at five germination times (12h, 3, 5, 8, 15 and 22 days after sowing). The data regarding the periods during reserve mobilization were subjected to regression analysis. The main source of reserve in safflower is lipids, followed by carbohydrates and proteins, with reductions of 37% for lipids, 3% for carbohydrates and 0.5% for proteins, during germination and seedling development. The mobilization of reserves of safflower seeds was accompanied by changes of cell features, which became vacualized and with multiple plastids, and by the synthesis of chlorophyll a, which peaked between 9 and 11 days after sowing, followed by the final reduction caused by senescence.