Stereological analysis of petiole of forage and grain soybean cultivars

Abstract

The structure of petiole resembles the stem structure in most of the legumes and has higher potential impact on digestibility than leaf lamina. Petiole anatomy of forage and grain soybean cultivars was analyzed using stereological method. The aim was to obtain data about petiole structure, to assess the proportion of different tissues from its proximal to distal end and to compare petiole characteristics between grain and forage cultivars. Lignified petiole tissues were xylem and sclerenchyma. Their volume densities (Vv) were the lowest in distal petiole part, closest to the leaf blade, whilst Vv of epidermis and collenchyma were the lowest in proximal region. Xylem proportion gradually increased towards the petiole base, whilst the proportion of phloem and the number of vascular bundles significantly increased from proximal to distal petiole end, probably as the result of bundle division along the petiole length. Thin epidermal and collenchyma tissue, the small size of vascular bundles and small groups of sclerenchyma are favorable characteristics concerning petiole digestibility.