Tolerância de seis acessos de Brachiaria spp. ao alagamento

Abstract

Some morphologic and physiological responses of Brachiaria brizantha cv. Marandu (BRA000591), BRA002844 (cv. Piatã), BRA004391 (cv. Arapoty), BRA003824, BRA003891 and B. ruziziensis BRA001911 were compared in plants grown in pots, under flooded and well-drained conditions, during five days. Flooding reduced leaf elongation rate in all the studied accessions. Under flooding leaf dry matter production was lower in all evaluated accessions, but in cv. Piatã. Root dry matter production was reduced by flooding in cv. Marandu and in BRA001911, while biomass allocated to roots was reduced by flooding only in BRA001911. It was not possible to detect differences between treatments in the percentage of biomass allocated to culms and leaves in any of the accessions. Flooding decreased the mean number of tillers in cv. Marandu, in BRA003824, BRA003891 and in BRA001911. Under flooding, relative growth rate was decreased in cv. Marandu, in BRA003824 and BRA001911. Flooding reduced net photosynthesis, stomatal conductance and transpiration of all the studied accessions, with exception of cv. Arapoty. The six accessions tested differed in their relative tolerance to flooding. Cultivar Arapoty was the relatively most tolerant. BRA001911 was the most sensitive, followed by cv. Marandu. BRA003824, BRA003891 and cv. Piatã were classified as intermediate in flooding tolerance.