EFFECT OF LEAF SURFACE REDUCTION IN COMMON BEAN (Phaseolus vulgaris L.) AVALIAÇÃO DO EFEITO DE DESFOLHA NA CULTURA DO FEIJOEIRO (Phaseolus vulgaris L.)

Abstract

The effects of leaf surface reduction on the vegetative grown and grain yield in common bean was evaluated in an experiment carried out at Goiânia, Goias, Brazil. Levels of 25%, 50% and 75% leaf surface reduction in 10, 17, 24, 31 and 38-days-old plants were tested. A second experiment was conduced using 0.3 x 0.7 m cages covered by a thin mesh tissue. Two, three, four and five adults of Diabrotica speciosa (Germar) ( Coleoptera , Chrysomelidae ) were kept inside the cage on each plant by 24 hours. Leaf area consumption was measured by an area meter. Results showed that no percentage of leaf reduction caused damage in plant height. The 25% of leaf area reduction in plants with 10- and 17- days-old do not reduce the grain yield, however, all levels of leaf area reduction decreased significantly the grain yield if plants were 24 days-old or older. The results showed also that each D. speciosa adult caused 7.8%, 5.8% and 3.% of leaf area reduction on one, two and three week-old plants, respectively. It was also conclude that 25% of leaf area reduction to the 24 days after the germination can be to provoke a reduction of 21,7% in the grain yield of bean crop. KEY-WORDS: Insecta; damage level; Diabrotica speciosa .