Quantitative relationships among vegetative organs and their conductive tissues in several millets. I. Morphological characters of successive shoot-units.

Abstract

Morphological characters of successive shoot-units on a main shoot (Fig. 1, 2) were observed in field grown millets, i.e. Setaria italica, Sorghum bicolor Pennisetum typhoideum, Panicum miliaceum, Echinochloa frumentacea, Eleusine coracana, Coix lacryma-jobi and Coix lacryma-jobi var. frumentacea. All species showed a linear, but species-specific relationship between the number of shoot-units with emerging leaf and those with emerging primary roots (Table 1). At maturing, the length and width of the leaf blade, length of leaf sheath, length of internode and the diameter of the stem increased acropetally, reached the maximum, then decreased (Fig. 3). The length of leaf sheath, length of internode, length of leaf blade and width of leaf blade reached the maximum in the order as stated above. The number and diameter of the primary roots increased acropetally. In all species examined, the shoot-units on the main stems can be divided into three shoot-unit groups (two groups in Eleusine coracana), i.e. 1st, 2nd and 3rd groups respectively, according to the acropetal trends in morphological characters, especially the length of internodes (Fig. 3). According to these trends, eight species can be ranked in a sequence. The bearing of the results on the mechanisms causing such morphological trends were discussed with regard to the developmental processes of each organ.