Influence of the shading caused by the maize plants on the anatomy of the bean leaf of different growth habits. II. Mesophyll

Abstract

The arrangement and thickness of the leaf mesophyll and leaflet area were studied in bean (Phaseolus vulgaris L.) cultivars with determinate (Canário 101) and indeterminate (Rio Tibagi and Costa Rica 1031) growth habit, grown under different light intensities determined by shading by maize plants. The cropping systems were: dried plants of maize cut at 10 cm from the soil surface, plants doubled over below the first ear and upright plants. The evaluations were made on the central leaflet of the third trifoliolate leaf at the median region. Measurements of photosynthetically active radiation (PAR) were taken weekly at different plant heights. The cropping systems with doubled over and upright maize plants, allied to intra and inter shading among bean plants caused a decrease in the total radiation. The arrangement of the palisade and spongy parenchyma in the leaf mesophyll was not influenced by the available radiation, but the thickness of those tissues and the leaf blade were influenced, leading to cell expansion of the structures. The spongy parenchyma was more influenced by the amount of radiation than the palisade parenchyma. The shading induced an increase in area of the leaflet.