The distribution and development of plants, to example of those that infest the agricultural areas, the is influenced several factors, exemply those tied the caraterísticas of the natural soil or imposed by the man. Like this being, the present research work objectified, to study the effect of growing levels of liming in the growth and state nutritional of Senna obtusifolia, it weed common in agricultural ecosystems. For this, the present research was developed, in conditions of Green House belonging to the Department of Applied Biology to the Agricultural, FCAVJ-UNESP, under randomized completely, with six treatments and four replications. The treatments were constituted in the amounts of liming : 00, 02, 04, 06, 08 and 10 t/ha, being the liming used the dolomítico roasted with 38% of Ca and 20% of MgO, with a relative power of total neutralization (PRNT) of 104%. The experimental portions had been constituted of pots of plastic with capacity of 5 litter filled with earth collected in the layer arável of a Latossolo Red Dark Distrófico, the moderate, medium texture. After a period of growth of 56 days the plants were collected and separated in its vegetative components, being placed to dry in stove of forced circulation of air (70ºC for 72 hours) for determination of the dry weight. After heavy, the material was triturated and analyzed the composition level of nutritions. The results for now obtained they evidenced negative effects of the growing levels of liming, on the growth of the plants of S. obtusifolia, being evidenced reductions in the values of the dry matter accumulated starting from the dose of 4 t/ha of calcareous (pH 5,8), with effects more marcantes in the roots. The application of growing doses of calcareous provoked in the soil a progressive increase in the texts of Ca and Mg, what perhaps can have stimulated the competition among cátions, reducing the absorption of K. The elements N and P was the more absorbed by the plant.
Weed; nutrition; pH