Temperature and moisture variations during the plantlet emergence period are the most important types of stress, representing the greatest hazards in cotton emergence. The objective of this study was to investigate the influence of type of stress on the germination performance of cotton seeds and determine germination test effectiveness at low temperature. Five seed lots were previously submitted to moisture content, germination, and vigor tests (germination at low temperature). The seeds from each lot were then submitted to temperature (18ºC and 35ºC) and water availability (40% and 80%) stresses conditions. After germination was conducted under a stress situation, evaluations were made for plantlet emergence percentage and velocity, and root length and above-ground part length. Root length and above-ground part length at 18ºC were more effective than plantlet emergence percentage in discriminating the seed lots with respect to their physiological potential. Seed exposure to stress produced by high water availability and low temperature cause reduced germination performance of the cotton seed lots and may represent the greatest hazards during plantlet emergence. The germination test at low temperature is effective to estimate plantlet performance under low and high temperature and low moisture conditions.
Gossypium hirsutum; vigor test; temperature; moisture
