Lichston, Juliana EspadaCosta, Daniel Ramos da2024-09-092024-09-092024-02-28COSTA, Daniel Ramos da. O efeito biofertilizante de Kappaphycus alvarezii (Doty) nas respostas morfofenológicas de plântulas de Carthamus tinctorius L. - uma contribuição para a agricultura sustentável no semiárido. Orientadora: Dra. Juliana Espada Lichston. 2024. 64f. Dissertação (Mestrado em Desenvolvimento e Meio Ambiente) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2024.https://repositorio.ufrn.br/handle/123456789/60070In recent years, there has been an intensified search for sustainable alternatives in agricultural production, aiming to increase the production of plant crops and enhance their resilience to climate and environmental changes. One valid alternative to enhance resistance to biotic and abiotic factors, soil and climatic conditions, and increase plant nutrition is the use of biofertilizers. Marine algae present a diverse range of biotechnological applications, one of which is as a plant biostimulant, providing essential nutrients and phytohormones for plant growth and development. The objective of this study was to evaluate the effect of applying a biofertilizer based on the marine macroalgae Kappaphycus alvarezii (Doty) on morphophenological responses during germination and initial growth of Carthamus tinctorius L. seedlings, as well as to assess the effects under thermal stress. The methodology involved collecting and obtaining crude liquid and lyophilized extract from the marine macroalgae for application in two concentrations of liquid biofertilizer (1 and 10%) in a germination system using Germitest paper, with five genotypes of safflower cultivars (IMAMT S525, IMAMT 1470, IMAMT 894, IMAMT 7329, and IMAMT 7529), incubated in a germination chamber with a photoperiod of 12 hours dark/12 hours light for a period of 8 days at temperatures of ± 30 and ± 35 °C. At the end of the incubation period, parameters such as germination percentage (% G) and Germination Speed Index (GSI) were evaluated, as well as phenometric parameters including shoot and root length (cm) and fresh and dry mass increments (g). The data obtained were analyzed using factorial ANOVA and Tukey test to assess the significance of the data compilation. Results showed that at concentrations of 1 and 10% of Kappaphycus alvarezii (Doty) biofertilizer, there were differences in plant growth and development parameters in all evaluated cultivar genotypes, especially in root length and fresh mass increment at ± 30 °C. For cultivars IMAMT 894 and IMAMT S525, at 1% biofertilizer concentration, mean values of germination and growth were higher than the control group, while cultivar IMAMT 1470 showed higher mean values at a concentration of 10% biofertilizer. Cultivar IMAMT 7329 showed higher mean values than the control group at a concentration of 10% at ± 30 °C, whereas cultivar IMAMT 7529 showed higher mean values at 1 and 10% biofertilizer concentrations at the same temperature. In conclusion, this study provided insights into the response of an organic biofertilizer of renewable and sustainable matrix as an alternative for a cultivar of agricultural interest in arid and semi-arid regions, demonstrating its viability and promising initial response for five safflower seed cultivars. Thus, contributing to the strengthening of coastal communities engaged in the cultivation and collection of marine macroalgae for bioproduct production, as well as serving as a biofertilizer alternative for use in family farming.Acesso AbertoBiofertilizanteKappaphycus alvareziiGerminaçãoSementesCártamomasterThesisCNPQ::CIENCIAS BIOLOGICAS