RESEARCH FOR DEVELOPMENT CSIR- CROPS RESEARCH INSTITUTE IN- HOUSE REVIEW: MARCH, 2012 BY BRIGHT BOAKYE PEPRAH

GOAL 1 APPROPRIATE TECHNOLOGIES DEVELOPED AND DISSEMINATED. Objective 1.1 High yielding, consumer acceptable food and industrial crop varieties tolerant to biotic and abiotic stresses developed

BACKGROUND Cassava ( Manihot esculenta Crantz ) is the cheapest starch staple and important source of dietary in Ghana, contributing about 22% AGDP Over 80% of the population rely on it as their main starch staple, consuming an of average 148kg per annum to provide 18% of dietary energy. Cassava is currently ranked as the number one food crop in Ghana and occupies 750,000 ha of farmland. Production is estimated at 9.7 million metric tonnes and about half is consumed as fufu and the remainder processed for example, into gari or kokonte.

RESEARCH ACTIVITY 1: STABILITY STUDIES OF SOME CASSAVA CLONES DEVELOPED BY CSIR- CRI Objectives:  To study the genotype x environment interaction  To assess the fresh yield performance of nine cassava genotypes.

 Cassava shows a strong and significant genotype x environment interaction effect (Fukuda, 1996; Kvitschal et al., 2007), due to its diverse difficult cropping condition, thus makes selection difficult.  Cassava breeding for superior cultivars should be performed taking Genotype x environment interaction effect in consideration.  Dixon et al., (1994) defines this G x E interaction as the change in cultivars relative performance over environments from differential response of the cultivar to various edaphic, climatic and biotic factors.

 A detailed assessment of genotype x environment interaction magnitude and significance is important to ensure greater precision in the release of high yielding and stable clones (Kvitschal et al., 2009).  Stable yields play a major role in developing countries, where small – scale farmers, particularly those living in marginal areas, are working towards risk- minization (Adugna and Labuschagne, 2002).

Field work  The clones included 5 hybrids; dl102/005, dl102/006, dl102/007, la02/007 and la02/026.  An improved check, dokuduade and three landraces (agric, lagos and debor) used in the hybrid development (Table 1)

Table 1. Materials for the study GenotypePedigreesourcestatus Dl102/005Debor x lagosCRIF1 Dl102/006debor x lagosCRIF1 Dl102/007Debor x lagosCRIF1 La02/007Lagos x agricCRIF1 La02/026Lagos x agricCRIF1 DokuduadeUnknwonCRIImproved AgricUnknownCRILandrace DeborUnknownCRILandrace LagosUnknownCRILandrace AfisiafiUnknownCRIImproved AkosuatumtumUnknownFarmerLandrace BosomensiaunknownFarmerlandrace

The experiment was planted across three locations (Ejura, Pokuase and Fumesua) for a season (2009/2010) Four row plots were used. The rows were 1m apart and each plot was 5m long. The experiment was arranged in a randomized complete block design with three replications at each location The experiment was set out under rain-fed conditions. Weeding was done as deemed necessary

Data collection Height of First Apical Branch Canopy Spread Plant Height Top Fresh Weight per plot Number of Storage Root per Plot Fresh Weight of Storage Root/Plot Dry Matter Percentage

Root weight Root number

Top weight

Wet Weight Chopping Dry matter determination

Data Analysis Data were subjected to Genstat (9.2 Edition) to determine the significance of the main effects and interactions and LSD was used to separate means where significance exists GGE biplot (version 6.3 Yan, 2001) was used to do a graphical analysis of genotype x environment effect

Results and Discussions Table 2: Mean performance of cassava clones (combined analysis) Genotypes FRESH ROOT YIELD (t/ha)DRY MATTER Agric49.7 (1)30.0 (6) Debor26.4 (9)34.3 (2) Lagos44.5 (2)25.9 (7) La02/ (3)31.8 (4) La02/ (4)37.7 (1) Dl102/ (5)31.8 (4) Dl102/ (8)25.8 (8) Dl102/ (7)30.7 (5) dokuduade33.4 (6)33.3 (3) Grand mean Lsd (0.05)

Table 3: Mean squares of 9 cassava genotypes harvested at 12months (Combined Analysis). Source of variance dfFresh root yield Dry matterr Genotypes ***76.66*** Environment **2.66ns Genotype x environment **7.43ns

Table 4: Sum of squares and proportion of total sum of squares of 9 cassava genotypes harvested at 12 months (Combined Analysis). Source of variancedfFresh root yield Dry matter Sun of squares (ss) % total ssSum of squares (ss) % total ss Genotype (G) Environment (E) Interaction (G x E )

All sources of variation was significant for fresh root yield but for dry matter content only genotype main effect was significant. The high impact of genotype main effect on dry matter content suggests the prospect for the improvement of the genotypes in relation to the trait. Also the absence of significant G x E effect for dry matter has also been reported by Aina et al., The high genotype (G) and low environment (E) effects, and relatively low GEI on dry matter may require fewer environments to distinguish genotypes with high performance. Environment (E) main effect was significant for fresh root yield but not significant for dry matter content

The significant effects (p<0.01) of environment indicates high differential genotypic responses across the different environments. This justifies the need for multilocational testing to be able to identify a good genotype for fresh root yield. The low impact of environment on fresh root yield was not expected since yield is a polygenic trait. This observation falls contrary with work done by Cach et al., 2006; Ssemakula and Dixon., 2007 on cassava

Figure 2: GGE biplot for average root yield and stability of different cassava Clones ENV1 = Fumesua ENV 2 = Pokuase and ENV 3 = Ejura

Conclusions Genotypic differences were established among the genotypes for fresh root yield and dry matter content.. The results showed that there is a prospect for the improvement of dry matter content among the genotypes. G x E interaction was significant for fresh root yield La02/026 was identified as the most stable genotype.

WAY FORWARD The experiment need to be repeated to confirm the results;  why fresh yield was less influence by environment  Farmers are interested in stable clones on their own fields, so G x E x Y will be important

Acknowledgements Generation Challenge Programme: Financial support CSIR: Crops research Institute (Root and Tuber Division) Rev Dr. Elizabeth Parkes Dr. Joe Manu- Aduening Mrs. Adelaide Agyeman Dr. Hans Adu-Dapaah Mr. Edem Lotsu Mr. Ohene Djan Miss Benedicta Nsiah- Frimpong Mr. Clement Agyemang Mr. Richard Aboagye Mr. Issah (Transport) Biochemistry department (CSIR-CRI)