ISHS Acta Horticulturae 703: II International Symposium on Sweetpotato and Cassava: Innovative Technologies for Commercialization
RESPONSE OF SWEETPOTATO (IPOMOEA BATATAS) TO APPLICATION OF NITROGEN AND PHOSPHORUS FERTILIZERS IN THE NORTHERN HIGHLANDS OF TANZANIA |
| Authors: | S.K. Sebastiani, A. Mgonja, F. Urio, T. Ndondi |
| Keywords: | fertilizer response, root yield, harvest index, biomass |
| Abstract:
Experiments were conducted in the Northern highlands of Tanzania to determine the response of sweetpotato to and agronomic optimum benefit of applying nitrogen and phosphorus fertilizer to volcanic soils. A sweetpotato local cultivar ‘Tengeru Red/Sinia’ was tested with different levels of nitrogen (0, 30 and 90 kg N ha-1) and phosphorus (0, 60 and 120 kg P ha-1) in a complete randomized block design. Analysis of variance revealed that both nitrogen and phosphorus had significant mean squares (p≤ 0.05) for fresh root and biomass yields. Nitrogen also affected significantly (p≤ 0.05) harvest index and plant vigor. There were significant nitrogen by phosphorus interaction effects on fresh root and biomass yields. Highest fresh root yield (21 t ha-1) was obtained from a treatment with 30 kg N ha-1 combined with 60 kg P ha-1. Lowest root yield (8.5 t ha-1) was obtained in the control treatment. Fresh root data were subjected to agronomic optimum benefit analysis by response curves on nitrogen and phosphorus. A quadratic model gave a better fit to both nitrogen and phosphorus (R2=1), and the agronomic optimum benefit was 46.0 kg N ha-1 and 73.3 kg P ha-1. Nitrogen and phosphorus were agronomically beneficial for increasing the fresh root yield by over 38%. Increased yields were associated with improved nutrient status in the soil through fertilizer application. | |
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