Influence of environmental factors on carpetgrass seed germination

The aim of this study was to verify the influence of temperature, light, substrate, sowing methods, and salt and water stress on carpetgrass (Axonopus affinis, in the Poaceae family) seed germination. All four trials were performed in a germination chamber under controlled conditions of temperature, moisture and photoperiod. Experimental designs were entirely randomized with 100 seeds per plot. For the study of temperature and light (Experiment 1), treatments were arranged in a 6 x 2 factorial scheme, with six temperature regimes (constant at 20, 25, 30, and 35°C, and alternate at 20 to 30 and 20 to 25°C) combined with two light conditions (light: 8 h of light and 16 h of dark, and dark: 24 h without light) and four replications. For the study of substrate and sowing methods (Experiment 2), there were four treatments (on paper, between paper, on sand, and in sand) with five replications. For the study of salt stress (Experiment 3), there were five treatments, composed of NaCl concentrations (0, 25, 50, 75 and 100 mM), with four replications. For the study of water stress, treatments were arranged in a 3 x 2 factorial scheme (Experiment 4), with three substrate water contents (50, 75 and 100% water retention capacity) and two sowing methods (on sand and in sand), and four replications. Germination percentage and rate were evaluated. It was concluded that seed germination was more effective at the alternate temperatures of 20 to 30 and 20 to 35°C, under light, sown on sand, on a paper substrate or between papers. The NaCl concentrations did not affect germination percentage; however, germination was slower as the NaCl concentration increased. Faster and higher germination occurred when seeds were sown on sand at 100% of its water retention capacity. Key words: Axonopus affinis, light, salt stress, substrate, temperature, water stress.