Ecophysiology of dwarf plantain hybrids in peri-urban areas of Cameroon
(2014)
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- Plantains (Musa spp., genome AAB) are one of the most important food crops in West and Central Africa. Progressive decline in plantains production over the years has been attributed to its susceptibility to black leaf streak disease (BLSD), drought and poor soil fertility. The general objective of this thesis is to evaluate new promising plantain hybrids recently developed by CARBAP, under the major constraints to plantain production in peri-urban areas of Cameroon. Two new dwarf plantain hybrids (C292 and F568) and their grand-mother landrace (Red Yade) were grown for two crop cycles in three locations offering contrasting pedo-climatic scenarii of soil fertility, available soil water, climate and BLSD pressure. Indicators of BLSD, plant growth and phenology, climate and soil water potential were monitored throughout the study and were used to interprete yield components on the three sites. This field study was complemented with experiments in controlled conditions to evaluate root system architecture and to estimate heritability for major root traits. A detailed characterisation of the pedo-climatic environments was carried out to establish the environmental contraints hinging on plantain growth in each site. Two sites were affected by BLSD which developed gradually in the hybrid C292, early in Red Yade and not in F568. The latter displayed a higher number of standing leaves and had an increased leaf longevity during the whole crop cycle, especially during the fruit filling phase, which was partly, but not only, attributed to its BLSD resistance. This led to increased fruit circumference and bunch weight in the three sites. C292 produced leaves of larger size, a considerably larger number of hands and fruits that should make it a highly productive hybrid in favorable environmental scenarii. Red Yade, the parental landrace, was the least yielding genotype. The analysis in rhizotrons revealed a higher root:shoot ratio for F568 compared to the other genotypes. This result indicates that this genotype tended to allocate more assimilates belowground. At the level of root morphology, F568 also differed from the two other genotypes by favoring the branching of the primary root at the cost of a reduced growth of the primary root. Broad-sense heritabilities for several root traits outreached 40%. Narrow-sense heritabilities (h²) were null for most shoot traits and low for all root traits. Weak correlations between the initial leaf area and most traits suggested that a significant part of the variability was related to plant size. These observations suggested that important ecophysiological traits segregated during the development of these new plantain hybrids and that the scope for breeding strategies targeting specific abiotic constraints is worth being considered.
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Sadom Mboula, L. (2014). Ecophysiology of dwarf plantain hybrids in peri-urban areas of Cameroon. https://hdl.handle.net/2078.5/47594