Agromorphological diversity study of a cassava (Manihot esculenta Crantz) collection from Burkina Faso Tighankoumi
1 3* Gmakouba ,
Somé
2 Koussao ,
Ernest Renan
3 Traore ,
Kossi Essotina
1 Kpemoua
and Jean-Didier
3 Zongo
1Institut
Togolais de Recherche Agronomique (ITRA), Cacavéli, BP 1163, Lomé, Togo. 2Institut de l’Environnement et de Recherches Agricoles (INERA), 01 3 BP476 Ouagadougou, Burkina Faso. Laboratoire de Génétique et de Biotechnologie Végétales, Université de Ouagadougou 03 BP 7021 Ouagadougou 03, Burkina Faso. *Corresponding author, E-mail :
[email protected] ;
[email protected] Tel : (+228) 90 85 25 56/ (+228)97 16 95 77
Materials and Methods
Introduction Cassava is one of the most important staple foods in the region of Burkina Faso. Even with a paramount feeding role, the productivity of the crop (7, 4 ton/ha¹) is lower than the achievable average (30tons/ha¹), due the cultivation of nonadapted varieties. On the other hand, the morphological characterization of cassava germplasm is a valuable tool in the selection and adoption of better varieties. This tool provides precise information about the germplasm, enabling a more effective exchange and use, as well as the determination of genetic diversity and has lower costs compared to molecular characterization. Therefore, the objective of this work was to analyze the phenotypic diversity of the accessions and its structure . Table 1: Mean performance of cassava accessions collected in Burkina Faso.
Trait
Min.
Max.
Mean
Plt_Hgt
88.33
203.33
NRPL
1
9.66
5.78
0.61
3.47
1.74
MRWPL
Results
SD
129.67 26.92
CV
F value
20.76
4.95**
2.08
26.55
4.44**
0.75
36.15
2.78**
HI
0.31
0.82
0.56
0.07
18.75
0.89
FRY(ton ha-1)
6.05
34.7
17.37
7.62
36.55
2.78
•
Collection of 48 cassava accessions in farmers fields in 05 agro ecological zones of Burkina Faso (Figure 1 and 2). Six improved varieties introduced from IITA was used as check .
Figure 1: Accessions collection in a field In Boromo Province of Burkina Faso
• The experiment was established at Farako Research Station(11°6’N; 4°20w’), Soils are sandy clay. • Alpha Lattice design, 04 replicates under rainfed conditions; Each genotype was established in a one-row plot comprising of 6 plants; No fertilizers or pesticides were applied to the crop; Trial was kept weed-free by regular manual weeding. • 33 agromorphological traits from the standard cassava descriptors of the IITA modified by Fukuda et al. (2010) were used. Data were taken at three, six, nine, and 12 months after planting. Accessions reaction to CMD (scale: 15) and CBB (scale: 1-5) begins at 3 months after planting, were observed under natural environmental disease pressure (IITA, 1990). Other traits recorded at harvest are: aboveground biomass, harvest index, storage root fresh weight and number of storage roots per plant. Qualitative traits were recorded on each plant per accession in a plot while quantitative traits recorded on 4 plants per accession in a plot. Descriptive analysis, Multiple Component Analysis, correlation coefficient analysis(MCA), Principal Component Analysis(PCA) and Cluster analysis using UPGMA to identify homogeneous phenotypic groups were performed.
Figure 2: Map of Burkina Faso showing the collection points. Table 3 : Correlation matrix of trait assessed for diseases, agronomic and yield traits CMD
CBB
PLTHT
NRPL
MRWP
CMD CBB
0.51**
PLTHT
-0.57**
-0.28
NRPL
-0.06
0.30
0.52**
MRWPL
0.23
-0.07
-0.02
0.12
HI
-0.11
0.15
-0.03
0.20
Descriptive analysis of qualitative traits revealed a phenotypic variability among accessions. The dendrogram revealed 3 morphotypes relatively little differentiated in real structuring between indigenous and introduced accessions. Discriminant analysis showed that three variable (plant height, average storage root number per plant and average storage root weight per plant), contribute the most in discriminating the different groups. Group I included short accessions (HPL= 112.74 cm) with many storage root per plant (7.5). Group II contained very tall accessions (HPL= 145.08 cm) with few number of storage root per plant (NTP= 5.3). Group III was composed mainly of accessions of intermediate plant height (HPL= 130.89 cm) with an average number of storage root (NTP= 5.4). The study showed a significantly negative correlation between plant height and CMD. There was a significant positive correlation between CMD and CBB. The plant height was positively correlated to the number of root per plant. Conclusion
0.11
Table 2: Mean performance of the 3 heterotic groups identified in the germplasm Group
III
II
I
df1
df2
F
p-value
Size
14
9
31 112.74
2
53
5.33***
˂0.0001
Plt_Hgt
130.8 145.08
NRPL
5.21
5.30
7.50
2
53
6.84***
˂0.0001
MRWPL 1.51
1.61
2.39
2
53
7.71***
˂0.0001
HI
0.55
0.56
2
53
0.01
0.968
0.56
The Characterization revealed high phenotypic diversity within the germplasm. Elevated diversity of genotypes demonstrated that genetic resources of cassava found in Burkina Faso are valuable resources for cassava breeding. The 3 heterotic groups offer the possibility of choice of parents for development of high yielding varieties with superior level of resistance to CMD.
