Abstract:
This study aims to assess the risks and opportunities posed by climate
change to potato growers in South Africa and to evaluate adaptation measures in the
form of changes in planting time growers could adopt to optimise land and water use
efficiencies in potato, using a climate model of past, present-day and future climate
over southern Africa and the LINTUL crop growth model. This was done for distinct
agro-ecosystems in South Africa: the southern Mediterranean area where potato still
is grown year round with a doubling of the number of hot days between 1960 and
2050, the Eastern Free State with summer crops only and Limpopo with currently
autumn, winter and spring crops where the number of hot days increases sevenfold
and in future the crop will mainly be grown in winter. A benefit here will be a drastic
reduction of frost days from 0.9 days per winter to 0. Potato crops in the agroecosystems
will benefit considerably from increased CO2 levels such as increased
tuber yield and reduced water use by the crop, if planting is shifted to appropriate
times of the year. When the crop is grown in hot periods, however, these benefits are
counteracted by an increased incidence of heat stress and increased evapotranspiration,
leading in some instances to considerably lower yields and water use efficiencies.
Therefore year-round total production at the Sandveld stabilizes at around
140 Mgha−1 (yield reduction in summer and yield increase in winter), increases by
about 30% in the Free State and stays at about 95 tha−1 at Limpopo where yield
