STOMATA AND MESOPHYLL CHARACTERISTICS OF BARLEY LEAF AS AFFECTED BY LIGHT - STEREOLOGICAL ANALYSIS

The anatomical structure of the second leaf blade of barley (Hordeum vulgare L. cv. Koral) was studied in plants exposed to a photosynthetic photon flux density (PPFD) of 200-mu-mol m-2 s-1 compared with those grown under 25-mu-mol m-2 s-1. Design-based stereological methods were used for the estimation of various leaf anatomical characteristics such as mesophyll volume, proportion of intercellular spaces, number of mesophyll cells, mean mesophyll cell volume, and internal leaf surface area. The structure of the mesophyll was more affected by different levels of PPFD than were the stomatal characteristics. Increased PPFD produced thicker leaves with a larger mesophyll volume having a higher number of less elongated mesophyll cells and a larger internal leaf surface area.