Crescimento e quebra da dormência de sementes em Ischaemun rugosum com hipoclorito de sódio

Abstract

Growth and dormancy breaking of Ischaemum rugosum seeds with sodium hypochlorite lschaemum rugosum Salisb. is one of the most important weeds of rice in the Maranhao State–Brazil, because it is difficult to control, and the plants have a high reproductive potential. The study was conducted to assess plant growth and to evaluate treatments for breaking seed dormancy of this weed. The treatments were three levels of irradiance (100, 75 and 50% of full sunlight), which were obtained using black shading net. The experiment was a randomized block design with four replications. To determine leaf area and dry matter, samples were collected at 14-day- intervals, after emergence. We also studied the effect of hot water (water at 60°C), acetone (100%) and sodium hypochlorite (2%) on dormancy breaking of seeds. The plant cycle was 110 days, dry matter accumulation and leaf area reached maximum values at 98 and 56 days after emergence (DAE), respectively. Plant height was higher in plants grown at 50% of full sunlight, in comparison with those grown at 100% irradiance. On average, each plant can produce 2000 seeds, which shows that this species has a remarkable reproductive potential. The most effective treatment for breaking dormancy of seeds was sodium hypochlorite (2%) for two hours.