Genotype × environment interaction and selection for drought adaptation in sweetpotato (Ipomoea batatas [L.] Lam.) in Mozambique
Euphytica
Genotype 3 environment interaction and selection for drought adaptation in sweetpotato (Ipomoea batatas [L.] Lam.) in Mozambique
0 R. Eyzaguirre W. J. Gru ̈neberg International Potato Center , Av. La Molina, 1895 La Molina, Lima , Peru
1 J. Ricardo Instituto de Investigac ̧a ̃o Agraria de Mozambique , Av. FPLM, 2698 Maputo , Mozambique
2 M. I. Andrade (&) A. Naico G. S. Makunde International Potato Center, IIAM , Av. FPLM, 2698 Maputo , Mozambique
3 Additive main effects multiplicative Regression Stability Storage root Water deficit
4 R. Ortiz Department of Plant Breeding, Swedish University of Agricultural Sciences , Sundsvagen 14, Box 101, 23053 Alnarp , Sweden
Sweetpotato is grown throughout the year in Mozambique but drought affects storage root yield and biomass productivity. The objectives of this research were to estimate the impact of genotype 9 environment interactions (G 9 E) in sweetpotato and select genotypes based on drought indices such as geometric mean, percent yield reduction, drought sensitivity index and harvest index. A total of 58 clones were evaluated during the dry season of 2006, 2008 and 2009. Two treatments were applied for this multi-year trial: full irrigation and without irrigation at the middle of root initiation growth stage. The field layout was a randomized complete block design with three replications. 'Jonathan', 'Resisto' and 'Tanzania' were the check cultivars in each treatment. Storage root and vine yields were recorded at harvest in the trials. Harvest index was computed from the yield data. The analysis of variance, regression and the additive main effects multiplicative interaction (AMMI) analyses, plus phenotypic coefficient of variation and ecovalence were used for dissecting the G 9 E and assessing the stability of each clone. Treatment, genotype 9 treatment and genotype 9 year (G 9 Y) interactions had highest contributions to the variation in storage root yield observed among clones. The stability of harvest index was significantly correlated with the absolute AMMI's IPCA1 and IPCA2 values for storage root yield. Cultivar performance varied within treatments. Four clones had significantly higher storage root yield (t ha-1) than 'Tanzania', the best check cultivar under drought. In conclusion, storage root yield (t ha-1) was negatively affected by drought and G 9 Y interaction. Harvest index stability and the geometric mean may be key to identify clones with storage root yield stability and high storage root yield under both treatments. At least two environments should be used at early breeding stages to consider harvest index in the early breeding cycle.
interaction; Ecovalence yield; Vine
Abbreviations
AMMI Additive main effects and multiplicative
interaction
CIP International Potato Center
G 9 E Genotype 9 environment interaction
HI Harvest index
IIAM Instituto de Investigac¸ao Agra´ria de
Moc¸ambique
RDM Root dry matter
TYLD Total storage root yield
Introduction
Sweetpotato provides household food security and is
an important source of energy due to its ability to grow
throughout the year in some areas of the sub-Saharan
Africa, where it ranks among the most widely grown
root crops
(Andrade et al. 2009)
. Mozambique grew
about 122,000 ha of sweetpotato with a harvest of
890,000 t of storage roots
(FAO 2015)
. The average
storage root yield was 7.3 t ha-1 in 2013. Sweetpotato
production doubled in Mozambique due to promotion
and dissemination of orange-fleshed (OFSP) cultivars
with the aim of alleviating vitamin A deficiency in the
diets, and replacing maize in areas affected by
frequent flood
(MICOA 2005)
and drought. There
are two growing seasons in Mozambique: rainy,
humid, hot summer (October–March) and dry, cool
winter season (May–July) near perennial rivers. The
summer cultivation of sweetpotato is affected by the
rainfall, which is often uneven, particularly in
southern Mozambique that is drier than the north of this
country.
Although sweetpotato has been regarded elsewhere
as a drought tolerant crop after the storage root
formation and towards physiological maturity
(Indira
and Kabeerathumma 1988; Valenzuela et al. 2000)
,
drought—as a result of uneven rainfall—may cause
significant storage root yield loss in Mozambique
(FAO 2004; MICOA 2005)
. There are some
sweetpotato cultivars showing some adaptation to drought
(Anselmo et al. 1998; Cha´vez et al. 2000; Ding et al.
1997; Hou et al. 1999; Maquia et al. 2013; Wang et al.
2003; Yang et al. 1999)
. Their adaptation depends on
various mechanisms that are affected by the onset and
intensity of drought. These mechanisms include
drought escape due to early and rapid root
development or early bulking and maturity
(Yen
et al. 1964; Bouwkamp 1985)
, drought avoidance
resulting from deep rooting (Ekanayake 1990),
relative water content and water use efficiency
(Kelm
2000; Zhang et al. 2006)
, and drought tolerance
relying on osmotic adjustment due to relative contents
of free (...truncated)