SOIL MOISTURE ON EMERGENCE AND INITIAL DEVELOPMENT OF Bidens pilosa

Abstract

Some species are used as cover crops, so they can produce and release products from their secondary metabolism. When these products are released in the environment, they are exposed to direct or indirect influences. Thus, this trial aimed to evaluate the influence of soil moisture content in plant decomposition, possibly caused by allelochemicals release. The influence of soil field capacity was evaluated by the decomposition of black oats (Avena strigosa Schreb), turnip (Vicia villosa Roth) and hairy vetch (Raphanus sativus L.)  residues, with 70 and 50% of water availability and the control. Pots (1.0 kg) were filled with sterilized and unsterilized soil, plus 30 g of plant residue, which remained in decomposition for four weeks before the experiment start. After that, five seeds of beggartick (Bidens pilosa L.) were sowed and seedling emergence was daily evaluated for 10 d. The emergence speed index and emergence speed were calculated. Five seedlings were transplanted at the 8th d and evaluated during 30 d, to obtain the initial development of plants, and to determine fresh and dry mass. Greatest growth inhibition of the weed tested occurred with 70% available water for plant emergence and with 50% for initial plant development.