Production Practices and Quality Assessment of Food Crops. Vol. 1

Improvement of Grain Legume Production in Semi-Arid Kenya 173
2.2. The tepary bean
Tepary bean, which belongs to the genus Phaseolus and subfamily Papilionoideae
of the family Leguminasea, originates from the semi-deserts and deserts of NW-
Mexico and SW-USA. It is native to the Sonoran Desert and has been grown here
for over 5000 years, predominantly by means of ‘flood water farming agriculture’
(Nabhan and Felger, 1978). The first scientific papers on tepary beans appeared at
the beginning of the 20th century (Freeman, 1913; Hendry, 1919), the emphasis
being placed on the botanical and ethno-historical aspects. The period 1915–1930
could be referred to as the ‘tepary boom’ (Nabhan and Felger, 1978) because it
was the first time that the crop was incorporated into the Dryland Farming Project
at the Arizona Agricultural Experimental Station.
From 1960, there were increased research activities on tepary beans, particularly
the biochemical and biophysical characteristics of the crop (Coyne and Serrano,
1963; Sullivan and Kinbacher, 1967). The drought, heat and disease resistance
properties of the crop were exploited and used in cross-breading programmes with
other less environmentally-hardened Phaseolus vulgaris L. varieties during the 1970s
(Mok , 1970). Tepary beans seem to possess capabilities for drought-resistance
and gives good yield in arid regions that are too dry for other beans. The results
of biochemical analysis (Coyne and Serrano, 1963) showed that the plant produces
high amounts of soluble solids such as glucose and sucrose in under sufficient or
insufficient water supply.
2.3. State of the art in tepary bean research in Kenya
The government of Kenya has recognized the important role the ASALs play and
will continue to play with respect to human settlement as well as production of
subsistence crops (Republic of Kenya, 1993). Currently, food production in the
ASALs has lagged behind population growth and as such there is an urgent need
to step-up food production for the expanding population (Bohlool et al., 1992).
One of the major steps towards increasing food production in the ASALs is the
use of modern technologies in agriculture and selection of suitable crop cultivars.
Dow (1989) emphasized the need for research on drought tolerant crop species of
short vegetative cycle, e.g. Pima-Papago maize (Zea mays) varieties (Tohono
O’odham Z16) and tepary beans (TB) (Phaseolus acutifolius), as one of the special
issues in development related to drought, desertification and food deficit in Africa.
Unfortunately, the use of the above mentioned technologies in the ASALs have
not been adequately adapted because of socio-economic constraints (Shisanya, 1999).
Most farmers in the ASALs are resource poor and cannot afford the required inputs,
mainly in the form of chemical N fertilizers. Legume-Rhizobium has been exploited
elsewhere as a substitute for the N fertilizers (Maingi et al., 1999; Gitonga et al.,
1999; Hornetz et al., 2000; Maingi et al., 2001). This technology uses the Rhizobiumlegume
symbiosis that has become particularly important because it has shown
very high rates of N 2 fixation (Zargar and Kahlon, 1995).
There is very little research work that has been carried out on the effectiveness
of N 2 fixation of indigenous (natural) and inoculated (host-specific) rhizobia strains