107
In recognition that OFSP was well liked by the population, especially young
children, but that better adapted varieties were needed, funds were raised to support
breeding in Mozambique. As over 50% of sweetpotato production was lost (both
white- and orange-fleshed) in the prolonged 2005 drought, the first step was to collect all landraces throughout the country that had survived. In total, 147 accessions
(both landraces and improved materials) were characterized morphologically and
molecularly. The best (in terms of high yield performance under water-stressed and
non-water stressed condition) were selected as parents to develop drought-tolerant
OFSP.
Breeding varieties to survive drought is a complex process. Drought can occur at
any point in the development cycle of the crop, and the varieties selected need to
perform well under water-stressed and non-water stressed conditions (Andrade
et al. 2016a; Makunde et al. 2017). For a variety to be permanently adopted, it needs
to have vigorous vines and roots left in the ground at harvest (a traditional source of
planting material) must sprout well at the beginning of the rains. With regards to
taste, a floury texture is preferred, a characteristic associated with dry matter contents of 28% or above.
The standard protocol historically used for many sweetpotato breeding programs
required a variety to develop over a period of 8 years, including: the crossing of the
new parents and generation of seed; the growing out of clones from those seeds; a
selection process over a number of years, specifically evaluating the variety’s agronomic and organoleptic characteristics with active farmer participation. The
Accelerated Breeding Scheme (ABS), unlike this traditional approach, exploits the
fact that each clone is a potential variety and has more sites earlier in the breeding
cycle, including one stress environment for the trait of interest (in this case a
drought-prone site). The ABS reduces the breeding cycle from 8 to 4–5 years
(Grüneberg et al. 2015).
By applying the ABS, 15 new drought-tolerant OFSP varieties were released in
Mozambique in 2011 (Andrade et al. 2016b). An additional four OFSP varieties
were released in 2016 (Andrade et al. 2016c). Some of these varieties have widelyadapted and others performed well in specific agroecologies with a range of maturity periods. Many farmers prefer the six improved early-maturing varieties, which
are ready in 3–4 months, because they enable them to manage rainy seasons of
unpredictable lengths (Alvaro et al. 2017). Some of the later maturing varieties are
deeper rooting which can be advantageous, because when the soil dries and cracks,
weevils can reach the roots and the deeper the root, the harder it is for the weevil to
reach it (Low et al. 2009).
There is strong evidence to suggest that combining OFSP introduction with
community- level nutrition education increases the intake of vitamin A in young
children and their mothers, and reduces VAD in children under 5 years of age (Low
et al. 2007; Hotz et al. 2012; Brauw et al. 2013). However, a major challenge in
drought prone areas has been ensuring quality planting material is available when
the rains begin (Fig. 9.2). In bimodal areas, vine retention is not a major issue
because farmers often use cuttings from an existing crop to start a new one. This
explains the larger per capita production of sweetpotato in East and Central Africa
9 Climate Change and Seed Systems of Roots, Tubers and Bananas: The Cases…
In recognition that OFSP was well liked by the population, especially young
children, but that better adapted varieties were needed, funds were raised to support
breeding in Mozambique. As over 50% of sweetpotato production was lost (both
white- and orange-fleshed) in the prolonged 2005 drought, the first step was to collect all landraces throughout the country that had survived. In total, 147 accessions
(both landraces and improved materials) were characterized morphologically and
molecularly. The best (in terms of high yield performance under water-stressed and
non-water stressed condition) were selected as parents to develop drought-tolerant
OFSP.
Breeding varieties to survive drought is a complex process. Drought can occur at
any point in the development cycle of the crop, and the varieties selected need to
perform well under water-stressed and non-water stressed conditions (Andrade
et al. 2016a; Makunde et al. 2017). For a variety to be permanently adopted, it needs
to have vigorous vines and roots left in the ground at harvest (a traditional source of
planting material) must sprout well at the beginning of the rains. With regards to
taste, a floury texture is preferred, a characteristic associated with dry matter contents of 28% or above.
The standard protocol historically used for many sweetpotato breeding programs
required a variety to develop over a period of 8 years, including: the crossing of the
new parents and generation of seed; the growing out of clones from those seeds; a
selection process over a number of years, specifically evaluating the variety’s agronomic and organoleptic characteristics with active farmer participation. The
Accelerated Breeding Scheme (ABS), unlike this traditional approach, exploits the
fact that each clone is a potential variety and has more sites earlier in the breeding
cycle, including one stress environment for the trait of interest (in this case a
drought-prone site). The ABS reduces the breeding cycle from 8 to 4–5 years
(Grüneberg et al. 2015).
By applying the ABS, 15 new drought-tolerant OFSP varieties were released in
Mozambique in 2011 (Andrade et al. 2016b). An additional four OFSP varieties
were released in 2016 (Andrade et al. 2016c). Some of these varieties have widelyadapted and others performed well in specific agroecologies with a range of maturity periods. Many farmers prefer the six improved early-maturing varieties, which
are ready in 3–4 months, because they enable them to manage rainy seasons of
unpredictable lengths (Alvaro et al. 2017). Some of the later maturing varieties are
deeper rooting which can be advantageous, because when the soil dries and cracks,
weevils can reach the roots and the deeper the root, the harder it is for the weevil to
reach it (Low et al. 2009).
There is strong evidence to suggest that combining OFSP introduction with
community- level nutrition education increases the intake of vitamin A in young
children and their mothers, and reduces VAD in children under 5 years of age (Low
et al. 2007; Hotz et al. 2012; Brauw et al. 2013). However, a major challenge in
drought prone areas has been ensuring quality planting material is available when
the rains begin (Fig. 9.2). In bimodal areas, vine retention is not a major issue
because farmers often use cuttings from an existing crop to start a new one. This
explains the larger per capita production of sweetpotato in East and Central Africa
9 Climate Change and Seed Systems of Roots, Tubers and Bananas: The Cases…