EFFECTS OF NITROGEN-FERTILIZATION ON GROWTH AND YIELD OF CASSAVA IN HAWAII .2. DRY-MATTER PRODUCTION AND EFFICIENCY OF PARTITIONING

A field experiment was conducted in 1987 on a Vertic Haplustoll on the Island of Oahu (Hawaii) to study dry matter production and efficiency of dry matter partitioning of cassava grown under increasing rates of applied nitrogen (N) (0, 50, 100, and 150 kg N/ha). A series of biomass harvests were collected throughout the growing season to examine the effects of differential N regimes on top and’ root growth. Although plant growth was partially stunted by waterlogging, N fertilization increased significantly top and total plant dry matter production but decreased the proportion of dry matter allocated to roots. The maximum dry matter partitioning ratio for roots (root dry weight/total dry weight) was 0.28 for the 150 kg N rate vs. 0.44 for the control (0 kg N). The sink capacity of branches was enhanced greatly by N fertilization; at the high N rates the proportion of dry matter allocated to branches increased almost linearly over time. The maximum dry matter partitioning ratio for branches (branch dry weight/total dry weight) was about 0.68 for the 150 kg N rate vs. 0.56 for the control. © 1990, Taylor & Francis Group, LLC. All rights reserved.