Anatomical investigations on 8 cultivars of rice (Oryza sativa L.), four from each of the traditional (local) and modem (high yielding) cultivars, were carried out to study the variation among the cultivars. The epidermis is single layered having cuticle of varying thickness. The number of hypodermal layer is more in modem cultivars compared to traditional ones. The vascular bundles are of two types, outer (small) and inner (large), in all the cultivars except Madhabshail-boro where additional median (medium) type is present in between outer and inner bundles. The number, position and arrangement of vascular bundles vary among the cultivars. The outer vascular bundles are embedded in the hypodermis and found to push outwards forming outgrowth of different shapes in all the cultivars except BR7 and BR3 where the wavy appearance in outer circumference of the stem is present. Some of the inner vascular bundles are attached or nearer to the hypodermis while the rest are away from it. The hollow pithis found to be smaller in modem cultivars compared to traditional ones. The higher number of mechanical tissues (hypodermal cells and inner vascular bundles) in modem cultivars imparts resistance to lodging.
展开▼
