| || || Leo, Pakoa|
| || || Growth and developmental responses of taro (Colocasia esculenta (L.) Schott) to three nitrogen fertilizer levels : developing key insights for the purpose of simulating management impacts using a biophysical crop model|
Institution: University of the South Pacific.
Subject: Taro -- Fertilizers -- Vanuatu -- Santo Island, Taro -- Vanuatu -- Santo Island -- Growth , Taro -- Research -- Vanuatu -- Santo Island
Call No.: pac SB 211 .T2 L46 2016
Copyright:20-40% of this thesis may be copied without the authors written permission
Abstract: This research evaluated the growth and development responses of two cultivars of Taro (Colocasia esculenta (L.) Schott) to three nitrogen fertilizer levels for the purpose of simulating management impacts using the biophysical crop model “Decision Support System for Agro Technology Transfer” (DSSAT). The local cultivars of taro used in this study were Sakius and Tarapatan. The study was conducted at VARTC, Santo Island, Vanuatu. The experiment was laid out in a split plot design with harvest dates as split-split plots. The study revealed that N treatments had significantly increased plant height, leaf area, corm fresh weight, corm dry weight, roots, petiole and leaf dry weights, as well as leaf and sucker numbers. However no significant differences between the two cultivars were seen in all parameters measured except in leaf numbers and corm fresh weight. Results also showed that when no N was applied the taro plants produced the lowest tuber weights (36.1 g), shortest average plant heights (50.69 cm), smallest leaf area (2300 cm2) and the least number of suckers (1.4). The application of 200 N kg/ha resulted in the highest tuber weights (50.30 g), largest average plant heights (70.53 cm) and the most number of leaves (7) recorded, however these increases were comparable to results from the application of 100 N kg/ha; tuber weights (47.58 g), average plant heights (67.89 cm) and number of suckers (5.2). Differences in the partitioning of dry matter to the above and below ground parts of the plant were also seen. In the below ground components, the corm accumulated more dry matter compared to the roots. Total plant biomass of the above ground components declined over harvests and below ground components increased. The second part of the study involved the use of the DSSAT computer modelling software to simulate the growth, development and yield of Taro under Vanuatu conditions (climate, soil and management) at VARTC and to simulate the future effect of climate variables (rainfall, temperature and carbon dioxide) on the growth, development and yield of the two cultivars. DSSAT simulations using current conditions at VARTC when compared to actual yields from the experiment under estimated corm yields of the two cultivars Sakius and Tarapatan, by 82% and 84% respectively at 0 N kg/ha. In contrast the model outputs at 100 N kg/ha only vii underestimated corm yield by 0.3% for Sakius and overestimated the corm yield of Tarapatan by 0.6%.