Bwalya, Angela (2012) Validation of the Aquacrop Model for Irrigated African Eggplant (Solanum Macrocarpon) at the Unza Field Station. Masters thesis, University of Zambia.
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Abstract
Crop growth simulation models are important tools for evaluating effects of water deficits to optimize water use under limited conditions to enhance sustainability and profitability of crop production. Simulation models are also useful tools for improving farm level water management and optimizing water use efficiency. The predominance of rain fed agriculture and on highly unreliable and poorly distributed rainfall in Zambia, makes agricultural production and productivity risky. Given the negative effects of climate change on agriculture experienced through decreasing crop water availability, there is need to consider the efficiency of use of the available water. This is particularly relevant for high value crops that can be grown under rain fed conditions, and are gaining in economic importance among, such as African eggplant. AquaCrop model was used to simulate crop biomass and yield of African eggplant (Solanum macrocarpon) in response to varying water application rates. African Eggplant is a minor vegetable crop in most African countries which is currently receiving interest. The main objective of this study was to validate AquaCrop model using irrigated African eggplant under deficit and full irrigation regimes. AquaCrop model was evaluated at the University of Zambia, field station for partially irrigated and rain fed eggplant crop under three water application rates at 50 percent, 75 percent and 100 percent of crop evapotranspiration (ETc). The 100 percent ETc treatment had sub-treatment with plastic cover (100 percent ETc+) and without plastic cover (100 percent ETc) as control. The experimental design was a Randomized Complete Block Design (RCBD) with four replications. Amount of applied irrigation water for the treatments varied from 197 to 364 mm while 194 mm was received as rainfall. The total aboveground biomass produced varied from 6.59 to 8.07 ton/ha, while the final fruit yield varied from 0.89 to 1.46 ton/ha. Water application significantly affected fruit yield (P<0.05) and harvest index (HI). However, no significant differences were observed in stem girth diameter, plant height, stover and dry matter produced. Furthermore, the water use efficiency increased with decrease in water application rate. Results from AquaCrop modelling over-estimated aboveground biomass production for all treatments except for the 100 percent water application treatment with plastic mulch cover. This may indicate no water stress during plant growth. For the predicted and measured biomass and canopy cover values, the prediction was comparable to the measured canopy values. Generally, the model performed satisfactorily for the growth of aboveground biomass, fruit yield, and canopy cover (CC) in the non-water-stressed treatments (100 percent ET with plastic cover) but it was less satisfactory in simulating severely water-stressed treatments. The ease of use of the AquaCrop model, the low requirement of input parameters and its sufficient degree of simulation accuracy, makes it a valuable tool for estimating crop productivity under rain fed conditions, supplementary and deficit irrigation and on-farm water management strategies for improving the efficiency of water use in agriculture.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | S Agriculture > S Agriculture (General) |
| Divisions: | Africana |
| Depositing User: | Geoffrey Obatsa |
| Date Deposited: | 14 Dec 2018 11:46 |
| Last Modified: | 14 Dec 2018 11:46 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/8640 |
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