Germinação de cártamo sob déficit hídrico, variação de temperatura e influência de glifosato

Abstract

Carthamus tinctorius L., popularly known as safflower, is a plant of Asian origin that has great potential for cultivation in semi-arid lands. The Brazilian northeast has great potential for family farming, but the edaphoclimatic conditions in the region can make local agriculture difficult. Therefore, plants that adapt to this climate and the management of important resources such as water is of paramount importance for the success of crops. With the increase demand for arable land, the region aims to safflower cultivation, therefore, the conscious use of herbicides is also an issue that needs to be studied in the field of agriculture. As glyphosate is the best-selling agrochemical in the world, it was chosen to be used in the present study which has the objective to test the effects of the herbicide on the germination of safflower cultivar 1470, as well as the impact of water stress and different temperatures. The study was accomplished at the Federal University of Rio Grande do Norte, at the Laboratório de Investigação de Matrizes Vegetais Energéticas (LIMVE). The selected seeds underwent adisinfection stage and were germinated in a roller system under water stress with treatments of 100%, 75%, 50%, 25% water and temperatures of 25°C, 32°C and 35°C, in addition of a sample with the presence of glyphosate. Data were computed and a ANOVA and Tukey statistical tests were performed based on the germination percentages and Germination Speed Index (IVG) calculated. Seeds did not show a statistical difference in germination percentage in all treatments, regardless of temperature. The germination speed varied and demonstrated statistical differences between temperatures and water proportions. The highest temperature was the only one noted not to be affected by the 25% water ratio, keeping the averages statistically the same. Regarding glyphosate, its presence negatively affected germination percentage and IVG, demonstrating a true statistical difference in all comparisons. For the species, the temperature factor seems to be more limiting in germination, which higher temperatures have a higher germination rate and IVG, regardless of water stress.