Níveis de sombreamento no crescimento e produtividade de alface romana

Abstract

This study have for aiming evaluate the interaction between shading levels and cultivars of romaine lettuce by analysis of growth and yield. The experiment was conducted at the Experimental Station Pr. Dr. Antônio Carlos dos Santos Pessoa, belonging to Universidade Estadual do Oeste do Paraná - Unioeste campus Marechal Cândido Rondon-PR in september-november 2012. The experimental design was randomized in blocks 4 x 3 factorial design with four replications, and the first factor consists in four cultivars of romaine lettuce (Luiza, SVR 2755, Sophia and Donna) and the second is three shading levels (0, 30 and 50%). For growth analysis, was performed on seven weekly evaluations on plant height, leaf number, leaf area, stem length and dry weight. It was determined the absolute growth rate, relative growth rate, net assimilation rate, leaf area ratio, specific leaf area and crown projection too. At harvest, was evaluated leafs numbers, hight plant, stem length, the aerial part fresh matter, commercial fresh matter and productivity. The 0% shaded environment, provided higher increase in dry matter accumulation and the growth rate of plants. For all the characteristics, it can be said that the use of shade screens in spring season did not improve productivity in romaine lettuces. The cv. Luiza showed smaller gains during the evaluation period, when compared to other, thus it can be said that the best performing cultivars were Donna and SVR for the productive caracters, the cv. Sophia has better value.