Agriculture Reference
In-Depth Information
identification of germplasm on which to experiment; fourth, selection or breeding
of both legumes and rhizobia that are adapted to each other and to the target soil
and climatic conditions; and fifth, assessing the implications of introducing new plant
and rhizobial material, including the threat in invasiveness. All of these steps involve
relatively old-fashioned agronomy, but can be greatly assisted by modern techniques,
in particular for screening germplasm.
6.3 Pharmaceutical uses
Legumes have been used to treat various ailments, for contraception and many other
purposes, including poisons, for thousands of years. For example, insecticides such as
derris are made from legumes. Many of these uses are described in Allen and Allen
(1981). However, there is now renewed interest in the potential therapeutic value of
plants generally, including legumes. The markets can be huge, in both conventional
and alternative medicine. Many of the species targeted are from developing countries,
where it is important that the indigenous knowledge is appropriately rewarded. It is
also essential that proper trials are conducted as to the efficacy of the alleged drug.
Of the many plant extracts currently being evaluated, one that appears to hold some
promise is from Sutherlandia frutescens , sometimes called Lessertia frutescens and com-
monly known as 'cancer bush' (Plate 6.8). This has been used for many years as a folk
medicine by people in South Africa, but now there is sufficiently strong evidence to
suggest that clinical trials be conducted to assess its potential for the control of various
diseases, including some forms of cancer (van Wyk & Albrecht, 2007). Howieson et al.
(2008) lists a number of other legumes that appear to give health benefits, including
extracts from the rootstock of Eriosema kraussianum that are said to have 75% of the
effect of Viagra (on rats).
6.4 Other uses
There is an increasing interest in teas, other than from Camellia sinensis , especially those
that have possible health benefits, such as being caffeine free. Two of the latter are from
nodulated legumes indigenous to South Africa. Best known is rooibos, or red bush tea,
made from the shoots of Aspalathus linearis . This plant can growon some highly infertile
soils, producing cluster roots, nodules and mycorrhizas to aid its nutrient acquisition.
Although originally harvested from wild material, selected germplasm is now widely
grown (Plate 2.11), processed on an industrial scale (Plate 6.9) and exported throughout
the world, being common on supermarket shelves. There are environmental concerns
in some areas that the native flora is being displaced and that too much biomass is
being harvested, leading to death of the A. linearis plants (personal observations). Less
well known is honeybush tea, for which the major species used commercially are
Cyclopia intermedia and to a lesser extent C. subternata , although a number of others are
used for home consumption. Much of the crop is still harvested fromwildmaterial, but
field-scale production is now getting underway and production is rising rapidly, both
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