International Journal of Horticulture, 2017, Vol.7, No.14, 115-123
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Potato growing zones in Kenya have a bi-modal rainfall pattern with the long rains falling between March and
June and the short rains from September to November. Exceptions are Meru which receive long rains in October
to December while in Kisii and Kericho, long rains occur in January to March and short rains in July to October
(Muthoni and Nyamongo, 2009). Because potato production in Kenya is mainly rainfed, the bi-modal rainfall
pattern determines potato supply; consequently, this determines prices due to high perishability of the produce as
well as lack of adequate storage facilities (MoALF, 2016). These potato growing areas also experience an average
minimum temperature of 8°C and an average maximum temperature of 23°C (Kinyae et al., 2004; Jaetzold et al.,
2006). These highlands also receive an annual rainfall of between 1050 to 1900 mm and have good soils (Guyton
et al., 1994; MoA, 1998; Kinyae et al., 2004). However, in the recent past, parts of these regions have been
experiencing low and erratic rainfall leading to a significant reduction in potato yield and quality (Figure 4).
Figure 4 Total annual rainfall in some potato growing areas in the Kenyan highlands
3 Impact of Climate Change on Crop Production
Impacts of climate change might be positive or negative depending on regions. For many regions however, global
warming will bring about a decrease in annual and seasonal rainfall, more erratic weather patterns and more
intense and frequent extreme weather events such as heatwaves, drought, storms and floods (Spore, 2015). The
low relative humidity due to decreased rainfall will favour increased insect vectors and viruses while high relative
humidity due increased rainfall will favour increased bacterial and fungal infections (Spore, 2015).
Climate change might negatively affect crop production especially in developing countries (Nelson, 2009). For
example, about 90% of the sub-Saharan African population depends on rainfed agriculture for food production
and climate change could result in decreased crop yields of 18% for southern Africa and 22% across sub-Saharan
Africa (Spore, 2015). The IPCC (2007) predicted a rise in global temperature by 1.8~4°C by the year 2100. In
addition, Africa will very likely (with > 90% probability) experience warming in greater measure than the global
average in all seasons (Lobell and Burke, 2010). Agricultural yields are not the only thing under threat from
climate change; a warmer climate could also make staple food crops more toxic. For example, mycotoxins
commonly found in maize, wheat sorghum and groundnuts are a real health concern in the hot, humid countries
(Spore, 2016). In addition, when a plant is stressed and in poor health such as during a heat wave or drought, it
can become more vulnerable to fungal infections (Spore, 2016).
4 Impact of Climate Change on Potato Production in WarmAreas like Kenya
Production of cool season crops like potatoes in the warm tropical areas will likely be a huge challenge in the
face of global warming. Potato is a cool season crop and grows best between 15°C and 18°C (Haverkort, 1990).
Potato is particularly vulnerable to heat due to its narrow production "window"; it requires mean daily
temperatures of 18-20°C and night-time temperatures less than 15°C (Borah et al., 1962). High temperatures
delay, impede or even inhibit tuber initiation (Minhas et al., 2006). It has also been suggested that high
temperature reduces yield by inhibiting starch synthesis in tubers (Krauss and Marschner, 1984; Mohabir and
