Root growth and morphology of five different yeiling upland rice varities in Northern Laos

Abstract

The yield of upland rice in northern Laos rapidly decline. The cause of this is not well understood. But it may be a result of a combination of reduced soil fertility, increased weed pressure, and increased pests and diseases. Root systems play an important role in the uptake of nutrients and water, so the distribution and activity of the roots may affect upland rice productivity and its capacity to cope with reduced soil fertility. The goal of this study was to evaluate the root systems of five upland rice varieties: Makhinsung (MS), Laboun (LB), Chaomad (CM), Nok (NK), and Vieng (VG). These varieties perform differently in soil which has been cropped continuously. Root and shoot samples were taken for a measuring of growth at 15, 25, and 45 days after emergence (DAE). The data showed differences in root number, root, length and thickness among the five varieties. CM, the variety that performed well in an intensively cropped system, had more roots, longer root length, finer roots and a higher root to shoot ratio than the other varieties NK and VG, the two varieties that performed poorly under a continuously cropped systems, had fewer, shorter and thicker roots, and a lower root to shoot ratio. In the last sampling, the average root length of MS and CM were greater than that of other three varieties. These differences in the characteristics of the root systems did not lead to differences in total N, P, K and Ca uptakes per plant in this experiment. This might be attributed to the limited soil volume in the pots and water. The benefits of root systems have been discussed in relation to the use of water and nutrient, leading to an increased productivity under field conditions.
of the different characteristics