Morphology of lateral roots of twelve rice cultivars of Bangladesh: dimension increase and diameter reduction in progressive root branching at the vegetative stage

Understanding morphology of lateral roots in rice is important in modeling different agricultural management system. The objective of the study was to explore the morphology of lateral roots of lowland transplanted-aman rice cultivars to mechanistically model length, surface area and volume of an individual root. Seedlings of twelve selected rice cultivars at 30 days of age were transplanted and a series of measurements was carried out on 14, 20, 33 and 60 days after transplantation (DAT). Lateral roots and root hairs were studied under a light microscope. Individual main axes produced up to second-order laterals. Mean main axis diameter and length of twelve cultivars measured 0.94 mm and 20.4 cm respectively at 60 days after transplantation. Diameter reduced at the first-order and second-order laterals up to 4.56 and 21.4 times respectively compared to main axis on 60 DAT. Root hair diameter measured 4.0 µm. An individual root on 60 DAT estimated 911 m in the length, 1714 cm 2 in the surface area and in the 467 mm 3 volume. Root hairs had the highest contribution towards total length and surface area of an individual root whereas main axis and first order laterals mostly contributed root volume.