Net profit at Sao Martinho SA , one of Brazil's biggest sugar and ethanol groups, was 6.4 million reais ($2.9 million) in the quarter ended March 31, down 50 percent from the year-earlier period, the company said in a filing on Monday night. The results for the final financial quarter of the company's 2013/14 cane crop season were hurt by the acquisition of Boa Vista milling assets formerly controlled by Biosev, a local sugar and ethanol unit of global commodities company Louis Dreyfus. The company's debt to EBITDA ratio remained stable in the quarter at 2.02, roughly the same as a year earlier and in the previous quarter. Net revenue was up 3 percent from the year-before quarter at 320.3 million reais.