Quantitative Relationships among Vegetative Organs and their Conductive Tissues in Several Millets : IV. Quantitative relationship between leaf. and root

Abstract

Quantitative relationship between leaves and primary roots was investigated on the main stems of field grown millets, i.e. Setaria italica. Sorghum bicolor, Pennisetum typhoideum, Panicum miliaceum, Echinochloa frumentacea, Eleusine coracana, and Coix lacryma-jobi. 1. The values of 'total leaf area/total cross sectional area of primary roots' at the maturing stage are nearly identical among the millets examined, except Eleusine coracana (Table 2). This means a common quantitative relationship exists on the main stem between total leaf area and total cross sectional area of primary roots. In the early growing stage, the total leaf area increased more rapidly than the total cross sectional area of primary roots. In later growing stage, the increase of total cross sectional area of the primary roots considerably surpassed that of the total leaf area (Fig. 1). Relationship between these two areas throughout plant growth varied quantitatively among species. In the early growing stage Setaria and Sorghum showed high values and Coix and Echinochloa showed low values of 'total leaf area/total cross sectional area of primary roots'. 2. The value of 'total cross sectional area of. vascular bundles at the base of leaf blades/total cross sectional area of steles at the base of primary roots' differed only slightly among species (Table 2). Total cross sectional area of steles in primary roots increased more rapidly than the total cross sectional area of vascular bundles in leaves (Fig. 2). This means that conductive tissue formation of primary roots gains increasing predominance over that of leaves. 3. The implications of quantitative relationship between roots and leaves was discussed from the view point of safety from environmental stresses.