Agriculture Reference
In-Depth Information
environments [26], which can be defi ned as areas with severe restricting
factors (or access to means of alleviating it) for acceptable crop perfor-
mance that are generally imposed by inherent local edapho-climatic condi-
tions (or lack of technology to circumvent them). Unfortunately, varieties
that are best suited to stress conditions are limited, inaccessible, or costly.
Due to the nature of breeding varieties for modern agriculture, conducted
largely under optimal high-yielding conditions, varieties that possess ge-
netic traits advantageous in low-input systems are often overlooked [27].
Several recent studies have shown that modern varieties can be out pro-
duced by traditional farm varieties under low-yielding conditions (Figure
2). Toure et al. [28] found that under low management, traditional lowland
rice varieties yielded more than modern varieties in Africa. Similar results
have been observed with other major crops, such as sorghum, wheat, and
barley [26,29,30], however this is not the case when produced in medi-
ate or high-input systems. Modern breeding programs have some success
at releasing maize and wheat varieties intended for marginal production
areas [31,32], however for the most part modern varieties have not been
widely accepted by local farmers. In India, improved varieties of upland
rice with yield advantages are available, however most farmers use tradi-
tional production practices that are incompatible, and therefore adoption
of these varieties has been slow [33]. Marginal farmers in Ethiopia have
also failed to adopt varieties recommended by breeders for the region due
to their inability to adapt to the variety soil conditions present [26]. Mod-
ern varieties are often developed by crosses between exotic lines that are
unable to adapt to stress or limiting conditions, as seen in several locally
unaccepted sorghum varieties [34].
Modern varieties that have been successfully adopted by low-input pro-
ducers generally have been developed using local germplasm, increasing
genotype × environment (G × E) interaction, adaptability, and therefore crop
performance [35]. It has been shown that the most effi cient way to improve
yields under low-input conditions is to select varieties while under low-in-
put or stress conditions [36]. However, this practice is done by few breeding
programs, leaving low-input producers without suitable cultivars. Low-in-
put farmers in developing regions must rely on landraces or creole variet-
ies, which have been selected for by the evolutionary process (naturally)
and the local farmers (artifi cially), and are often exchanged among them.
