Crescimento e anatomia foliar de plantas jovens de Mikania glomerata Sprengel (guaco) submetidas a diferentes fotoperíodos

Abstract

Mikania glomerata Sprengel, an important medicinal species, popularly known as "guaco", "coração de Jesus", "guaco liso", "guaco cheiroso", "cipó caatinga" and "erva de cobra" was investigated. The photoperiods of 8, 12, 16 and 20 hours were studied. After 90 days' treatment; total dry matter weight, partitioned (among leaves, branches and roots), leaf area, leaf area ratio, leaf weight ratio and specific leaf area were determined. The plants growth changed with photoperiod there was an increase in the total and partitioned dry matter up to 16 hours followed by a fall when photoperiod was increased from 16 to 20 hours. Leaf area and number of leaves have been growing till the 20-hours photoperiod. There was a reduction of the specific leaf area and leaf area ratio with the increase of photoperiod. Concerning leaf weight ratio, there was also a decrease when photoperiod was from 8 to 16 hours, however, when photoperiod was from 16 to 20 hours, there was a trend toward increase. The treatments effect on the thickening of leaf tissue was observed. The photoperiod had positive result in the characteristics associated with growth, foliar anatomy and photosynthetic as: total biomass production, leaf area, leaf number, partitioned biomass to several plant organs.