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Genome Variability and Plant Age Influence
Susceptibility to Moisture Stress in the
Cultivated Bananas (Musa species)
1Baiyeri,
K. P. and 2Ortese, E.
1Dept. of Crop Science, University of Nigeria, Nsukka, Nigeria.
2Akperan Orshi College of Agriculture, Yandev, Benue State, Nigeria.
IeCAB2010 held on 1-15 June
2010
INTRODUCTION
 Water stress is one of the major environmental
constraints that limit crop productivity worldwide.
 Consequent on climatic change, moisture
availability (in terms of quantity, quality and
duration) has become very unpredictable in most
places.
 Moisture availability has been identified as one of
the most critical productivity determining factors in
Musa species (Robinson and Bower, 1986; Turner
et al., 2007).
IeCAB2010 held on 1-15 June
2010
Introduction…
 Water deficit imposes huge reductions in crop yield through
diminished leaf carbon fixation and general growth inhibition.
 However, the degree of plant susceptibility to transient or
prolonged moisture deficits is somewhat dependent on the plant’s
physiological growth stage during the time of water stress (Hall
et al., 1981 ).
 The deleterious effects of moisture stress in most species are
more disastrous during the reproductive growth phase (Evans,
1993); another precarious stage is the juvenile seedling stage.
IeCAB2010 held on 1-15 June
2010
Introduction …
 Existing information suggests that hardiness in
Musa species is influenced by genomic grouping.
 The cultivated bananas (Musa species) comprise of
three main genomic groups (AAA, AAB, ABB), but
with the array of emerging improved genotypes,
there is need to evaluate genomic responses to
moisture stress with a view to identifying putative
tolerant or less susceptible genotype(s).
IeCAB2010 held on 1-15 June
2010
Objective
To study the influence of plant age and genome
composition on the susceptibility of Musa plants
to transient drought condition.
IeCAB2010 held on 1-15 June
2010
Materials and Methods
 Experimental Site: The study was conducted in a glasshouse of
the Department of Crop Science, University of Nigeria, Nsukka.
Nsukka is located 6o 52′N, 7o 24′E and 447.2 m above sea level,
in the derived savanna agro-ecology of Nigeria.
 Design of Experiment: A six-week moisture stress period was imposed on six
Musa genotypes comprising of two dessert bananas (AAA), two plantains
(AAB) and two ABB cooking bananas at varying growth ages of 8, 12 or 16
weeks after planting. These were evaluated alongside the control (unstressed)
plants in a 6 x 4 factorial in completely randomized design (CRD) of five
replications. Each genomic group consisted of one landrace triploid (3x) and a
hybrid tetraploid (4x) genotype.
IeCAB2010 held on 1-15 June
2010
Materials and Methods …
Treatment application:
 Fairly uniform early sword suckers were used in
the study; these were raised in 17 kg of topsoil.
 At the specific age of introducing water stress,
watering was withdrawn for six weeks and
thereafter re-introduced for another six weeks.
IeCAB2010 held on 1-15 June
2010
Data Collection and Analysis
Growth changes in:




Plant height
Plant girth
Number of live leaves, and
Leaf area were evaluated after the six-week drought
and rehydration cycles.
All data collected were subjected to analysis of variance
for factorials in CRD using GENSTAT Release 7.2
DE (GENSTAT, 2007). The separation of treatment
means for significant effects was by least significant
difference (LSD) at 5 percent probability level as
described in Steel and Torrie (1980).
IeCAB2010 held on 1-15 June
2010
Results
Susceptibility to moisture stress varied with plant age, genome group and
ploidy levels.
 The effects of moisture stress were found to be most severe in the 16-week
plants, whereas the 8- and 12-week-old plants had a fair tolerance.
Considering the mean values across the six genotypes (Table 1), stress effects
on leaf area, plant girth and number of live leaves were more severe on the
16-week-old plants.
 The negative values observed in leaf area, plant height and girth in the 16weeks plants after the stress (Table 1) and rehydration cycle (Table 2) are
indications of shrinkage or outright loss of plant parts due to tissue
desiccation.
 The percentage survival values on Table 2 showed clearly that the 16-weekold plants were more susceptible to the transient drought.
IeCAB2010 held on 1-15 June
2010
Results …
The cooking bananas (ABB) and plantains (AAB) were more
drought-tolerant than the AAA-dessert bananas.
 The cooking bananas (‘Fougamou’ & ‘BITA 7’) and plantains
(‘Agbagba’ & ‘PITA 22’) had a better growth recovery (Table 2) as
evident from the higher values recorded in plant height, girth and number
of leaves per plant after the rehydration period.
 Besides, the dessert bananas had a very poor survival percentage,
although the landrace genotypes ‘Agbagba’ and ‘Fougamou’ were
equally affected.
 Similarly, the landrace triploid genotypes were relatively more
susceptible than the tetraploid hybrids. The mean values for number of
leaves, leaf area and plant girth (Table 1) showed the landrace genotypes
in plantains and dessert bananas to be more sensitive to moisture stress
than the tetraploid counterparts.
IeCAB2010 held on 1-15 June
2010
Table 1: Changes in growth parameters of six Musa genotypes exposed to moisture stress
at 8, 12 & 16 weeks after planting.
Plantains
Dessert Bananas
Cooking Bananas
Component
of Growth
Plant Age at
onset of stress
(weeks)
Agbagba
[3x]
PITA
22 [4x]
Nsukka
Local [3x]
FHIA
17 [4x]
Fougamou
[3x]
BITA
7 [4x]
Mean
Leaf Area
(cm2)
8
12
16
Mean
8.8
8.6
-1446.4
-476.3
-11.5
2.7
-4.0
-4.3
-86.2
7.0
11.5
-22.6
7.8
8.0
8.0
7.9
-20.7
1.7
3.9
-5.6
-366.8
7.3
13.0
-115.5
-78.1
5.9
-235.7
-
Number of
Leaves
8
12
16
Mean
-5.4
-5.0
-6.0
-5.5
-2.7
-3.3
-5.2
-3.8
-3.4
-6.4
-7.5
-5.8
-2.8
-4.0
-5.5
-4.1
-2.2
-3.0
-4.0
-3.1
-3.7
-2.7
-5.0
-3.8
-3.4
-4.1
-5.5
-
Girth (cm)
8
12
16
Mean
-0.6
0.0
-2.0
-0.9
-0.4
0.0
-0.8
-0.4
-0.4
0.0
-1.2
-0.5
0.2
0.0
-0.5
-0.1
-0.7
0.0
-2.5
-1.1
-0.4
0.0
-3.0
-1.1
-0.4
0.0
-1.7
-
Height (cm)
8
12
16
Mean
0.0
0.6
3.0
1.2
-0.3
0.5
2.3
0.8
0.2
0.4
4.0
1.5
0.2
0.7
3.5
1.5
-0.4
0.3
1.0
0.3
0.0
0.8
1.0
0.6
-0.1
0.5
2.5
-
Girth
0.5
0.3
0.8
Height
0.6
0.4
1.0
LSD (0.05)
Genotype (G)
Age (A)
GxA
Leaf Area
134.8
95.3
233.5
Number of Leaves
1.0
0.7
ns
ns = non-significant at 5% probability level
Table 2: The recovery pattern and changes in growth components of six Musa genotypes
exposed to moisture stress at varying ages estimated after a 6-week rehydration cycle.
Plantains
Dessert Bananas
Cooking Bananas
Component
of Growth
Plant Age at
onset of stress
(weeks)
Agbagba
[3x]
PITA
22 [4x]
Nsukka
Local [3x]
FHIA
17 [4x]
Fougamou
[3x]
BITA
7 [4x]
Mean
Leaf Area
(cm2)
8
12
16
Mean
38.8
12.2
-1166.4
-371.8
87.8
16.3
83.2
62.4
42.0
22.8
-329.0
-88.1
143.6
18.2
-2028.0
-622.1
45.8
14.5
-1449.0
-462.9
29.3
32.3
-145.0
-27.8
64.5
19.4
-839.0
-
Number of
Leaves
8
12
16
Mean
2.2
1.8
3.0
2.3
3.2
2.7
3.3
3.1
1.6
1.6
2.0
1.7
3.0
2.6
2.0
2.5
2.0
2.0
3.0
2.3
3.3
2.3
3.5
3.0
2.6
2.2
2.8
-
Girth (cm)
8
12
16
Mean
1.4
1.0
3.0
1.8
1.5
1.7
1.8
1.6
2.2
0.8
2.5
1.8
1.2
1.8
-5.0
-0.7
3.2
1.0
-2.0
0.7
1.3
1.0
10.5
4.2
1.8
1.2
1.8
-
Height (cm)
8
12
16
Mean
6.8
2.4
-16.8
-2.5
7.2
2.7
5.7
5.2
6.4
2.8
-11.0
-0.6
7.0
3.4
-45.0
-11.5
7.3
4.0
-11.0
0.1
6.8
3.0
36.7
15.5
6.9
3.1
-6.9
-
Percentage
survival (%)
8
12
16
Control
100
100
33
100
100
100
80
100
100
100
40
100
100
100
40
100
100
100
50
100
100
100
100
100
100
100
57.2
100
LSD (0.05)
Genotype (G)
Age (A)
GxA
Leaf Area
107.2
75.8
185.7
Number of Leaves
Girth
Height
0.4
1.9
6.3
0.3
ns
4.4
0.6
3.2
10.8
ns = non-significant at 5% probability level
Conclusion and application of findings
 This study suggests that Musa crops at their early vegetative growth stage are more likely to
withstand moisture stress than the older plants. Field planting and other cultural practices
(like mulching and irrigation) should be conscientiously planned to avoid prolonged
exposure of plants to drought, particularly at the reproductive transition phase.
 The differential sensitivities of the genomic groups to the induced moisture stress makes
breeding a viable option for upgrading drought resistance/tolerance in bananas in readiness
for the apparent change in global climate.
IeCAB2010 held on 1-15 June
2010