Growth of the Indian lotus (Nelumbo nucifera GAERTN.) and the influence of tuber density on foliage structure and biomass

Abstract

The growth of Nelumbo nucifera GAERTN. was investigated at an artificial stand in outdoor concrete ponds. The ratio of above- to below-ground biomass (T/R ratio) ranged from 0.3 to 3. Although N. nucifera is a perennial, the reproductive organ (tuber) begins to form later in the growing period than in annual plants ; in addition, the life span of the tuber is less than one year. Maximum relative growth rate was 0.037 g·g-1·day-1 in July.The leaf area index of floating leaves did not exceed 1 m2·m-2. The influence of initial tuber density on the foliage structure and below-ground biomass of N. nucifera were investigated. The initial death rate at the time of lamina rolling increased with leaf density. Control of the density of floating leaves was done twice ; once at the early stage of lamina rolling, and again at the late stage of the fully expanded leaf. The below-ground biomass in the following spring did not correlate with initial tuber size. When the tuber biomass was under about 400 g dry weight·m-2, net production of below-ground biomass of the N. nucifera stand seems to have attained a plus value. N. nucifera exhibited typical pioneer characteristics in an environment of frequent disturbances such as flooding, i.e., a high T/R ratio, high vegetative propagation by stolons and a short life span of the tuber.