Cassava Varieties Research Articles

Cassava Production, Processing and Utilization in South Western Part of Ethiopia

Cassava is a root crop grown and consumed in south western part of Ethiopia. A survey was conducted to assess the production status, processing and utilization of cassava in three zones in South Western part of Ethiopia. A total of 63 farmers from five Cassava producing Districts were randomly selected for interview. A well-structured questionnaire was administered to individual respondent. The survey result showed that most of the farmers on average allocated less than 0.25ha of land for cassava production and none of the respondents were used improved cassava varieties. More than 86% of the farmers sold fresh cassava while others sold after processing. Of the interviewed farmers 98.4% of the respondents had awareness about hydrogen cyanide content of cassava and conducted different removal measures. More than half of the interviewed farmers responded that most of cassava produced in the area was used for home consumption. Less than 40% of them were used for both market and home consumption. Of the total farmers, 53% of the farmers consumed cassava by boiling and frying, while the others consume either by boiling or frying.

Effect of processing and variety on starch digestibility and glycemic index of popular foods made from cassava (Manihot esculenta)

In Sub-Saharan Africa (SSA), the prevalence of diabetes mellitus (DM) is rapidly increasing even in populations with significant undernutrition. The role of energy dense staple crops such as cassava is under query and not yet well understood. In this study, varieties of cassava, made into popular SSA products (fufu and gari dough) were studied for their resistant starch (RS), rapidly digestible starch (RDS) and glycemic index (GI). While the glycemic properties of the varieties studied did not differ significantly, processing any variety into either fufu or gari distinctly impacted RS, RDS and predicted GI (pGI) differently. Specifically, fufu had highest range of RS (1.1–2.1 g/100 g) while gari dough had highest RDS (1.1–1.4 g/100 g) and pGI (54–67). The results from this probe imply that fufu, when consumed, will release glucose in a slower manner than gari, therefore may be better suited in the dietary prevention and management of DM.

Genome-wide association study of drought tolerance in cassava

Despite being considered a drought-tolerant species, cassava (Manihot esculenta Crantz) exhibits reduced growth and productivity under prolonged water stress. Therefore, the objective of this study was to identify the genomic regions associated with water deficit in cassava using a genome-wide association study (GWAS). A total of 49 cassava genotypes were evaluated under two water conditions: irrigated (control) and water deficit. An additional set of 252 clones grown for several years under water deficit conditions were used to validate the GWAS. The following traits were evaluated: yields of storage roots (RoY), shoots (ShY), and starch (StY); root dry matter content (DMC); drought tolerance index (DTI) and drought tolerance stability index (DTSI). The GWAS was performed using a multiple mixed linear model with a kinship matrix and population structure for each trait and water condition. Broad-sense heritability ( $${h}^{2}$$ ) estimates were variable depending on the water conditions and characteristics under analysis. Overall, 62 single nucleotide polymorphisms (SNPs) were identified across all 18 cassava chromosomes. Additionally, it was possible to identify specific and stable markers across environments. The identified SNPs comprise approximately 160 transcripts, of which 119 were previously described and 41 have known functional annotations. Some of these transcripts are related to proteins involved in drought tolerance, such as APETALA 2 domain (AP2), photosystem II oxygen-evolving enhancer protein, PR5-like receptor kinase-related, beta-fructofuranosidase/saccharase, leucine zipper, and bZIP transcription factor. There is great potential for applying these SNPs in the marker-assisted selection of new cassava varieties that are tolerant of water deficit.

Evaluation of Newly Released Cassava Varieties for Yield Performance, Reactions to Cassava Diseases and Farmers’ Preference in Adjumani District of Uganda

Cassava viral diseases particularly cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) have put pressure on cassava breeders to develop varieties that are resistant/tolerant to them. Several cassava varieties have been rolled out to farmers with the latest being NAROCASS series that are tolerant to these diseases. The yield performance of these new varieties have not been documented in some sub zones like Adjumani district that falls within a major West Nile agro-ecology of Uganda. Therefore this study sought to established yield performances of, reactions to major diseases, and farmers’ preference to these newly released cassava varieties in Adjumani. Results showed significant (P ≤ 0.05) differences among cassava varieties and experimental sites for all the parameters evaluated. Average yield performance by varieties were in the order of a local cassava—Alifasia (8.7 t/Ha) lowest, NAROCASS 2 (18.55 t/Ha), NASE 14 (33.97 t/Ha), NASE 19 (41.26 t/Ha), and NAROCASS 1 (41.71 t/Ha) highest. CMD foliar symptom was present at all sites on a local cassava—Alifasia, and on NAROCASS 1 in Ayiri parish, Ukusijoni sub-county. CBSD foliar symptoms were observed on off-types (TME 14) in the plot of NASE 14 in Miniki Parish only whereas CBSD root necrosis was observed at all sites on the local cassava—Alifasia, and on NASE 19 in Maaji parish, Ukusijoni sub-county. Cassava root rot disease was localised in Ukusijoni sub-county only. Farmers’ preferences to these newly released cassava varieties were in the order of NASE 19 (40.96%), NAROCASS 1 (24.86%), NAROCASS 2 (15.82.28%), NASE 14 (15.54%), and a Local cassava—Alifasia (2.83%). Result from this study strengthens the information gap in the breeding process towards developing a cassava variety with farmer-preferred attributes, and can also inform the utilisation of these improved cassava varieties in Adjumani district.

The effect of of cassava variety and fermentation duration on the texture and acceptabiity of cooked-dried growol

Cassava is a staple food source of carbohydrates, which is consumed in various forms such as growol, gatot and tiwul. Growol is produced through a fermentation process and therefore, has a sour taste typical. As an intermediate moisture food, it has a shelf life of just 3-4 days and is susceptible to mold growth. Previous studies have shown that a drying process may extend its shelf life to more than 6 months. The problem in carrying out this process was that growol producers in rural industries always make use of a mixture of several cassava varieties and fermentation was carried out for 2-3 days. Due to this reason, its physical and chemical properties varied. This study aims to evaluate the effect of the cassava variety and fermentation time on the texture and acceptability of cooked-dried growol. This research used three cassava varieties i.e. Meni, Ketan, Lanting and the fermentation time was 2 and 4 days. The fresh cassavas and dried-growols were analyzed for their starch, amylose and moisture content. Furthermore, the acceptability was determined by cooking each dried-growol using a rice cooker and its ratio to water was 1:2. Afterwards, they were tested for texture and preference level through a hedonic test. The results showed that the starch content of cassavas and their acceptability were significantly different, whereas the texture of cooked-dried growol was not significantly different The acceptable was produced with Meni cassava variety and fermentation time of 2 days.

Comparison Waterlogging Tolerance Potential of Cassava

This experiment was conducted to evaluate the waterlogging tolerance of cassava. Five cassava genotypes from CIAT: CM9912-167, GM214-62, GM1263-6, GM1406-13 and GM1521-10, were used to assess the impact of artificial waterlogging conditions on growth and development of cassava. Cassava plantlets (in vitro) were cultivated in soil pots, and after 3 months of growth, they were waterlogged for 12 days. After three days of waterlogging, it was found that all 5 genotypes of cassava were affected by the waterlogged conditions. Notably, the variety of CM9912-167 clearly showed physiological changes such as chlorosis of leaves, wilting leaves and some plants even died within 6 days. Other varieties of cassava showed a belated onset of symptoms. Genotypes GM1406-13 and GM1512-10 showed the highest percent of chlorosis leaves, they resisted the effects of waterlogging for 12 days which was the longest time period for the genotypes tested. Through this experiment, cassava has two types of response to flooding. The first was cassava showing early yellow leaf, starting from old leaves and losing those yellow leaves. The other was withered whole the plant, then leaves dries and fall off, only a few young leaves on the top. In conclusion, cassava with yellow leaves is more resistant to flooding.

Postharvest physiological deterioration in cassava: potential problems, possible inhibition, and resistant level identification

Cassava roots can only be utilized quickly because the roots suffer physiological damage in only 1–3 days after harvest because of postharvest physiological deterioration (PPD). Once the cassava roots are physiologically damaged, they cannot either be consumed or marketed. Indonesia is the second-largest cassava producer in Southeast Asia that is most used for food and feeds. Unless there is a solution, the PPD problem may become the main obstacle in cassava production. Therefore, finding solutions to the PPD problem in cassava is necessary, may be approached either by treatment to inhibit PPD occurrences, identification of tolerance accessions among cassava germplasm, and development of PPD tolerance cassava through breeding programs. In our research, the identification method was done by applying various staining methods to detect color changes associated with PPD symptoms during the cassava storage period and then compared to the conventional observation of PPD symptoms. Subsequently, the effective staining approaches are used to evaluate various genotypes’ responses in the cassava germplasm collections. Finally, the breeding approaches to develop PPD tolerance cassava varieties are outlined. Hopefully, with these research results, the solution for PPD problems associated with cassava production in Indonesia will be available.

Determination of proximate composition, amino acids, minerals and phytochemical profile of Cassava (Manihot esculenta) peel from sweet cassava variety grown in Yobe State of North Eastern Nigeria

The proximate composition, amino acid, mineral, and Phytochemical content of Cassava peel was determined. The peels were found to contain 8.70 % moisture, 4.89 % crude protein,
 8.75 % crude fiber, 2.15 % crude fat, 8.93 % ash. Nitrogen free extract and metabolizable energy values were 66.56 % and 2717.96kcal, respectively. The results of amino acid content revealed that the histidine and tyrosine are the most limiting amino acid with values of 0.005% each. Essential amino acids such as lysine, leucine, methionine and Isoleucine with values of 0.032, 0.067, 0.076 and 0.070% were low. Mineral profile revealed that magnesium (913.74mg/kg) and iron (111.50mg/kg) as the most abundant mineral. Concentrations of phytochemicals were 26.06, 699.8, 0.063, 24.81,8.37,1457mg/100g and 2.84 for saponin, tannin, hydrogen cyanide, phytate, trypsin inhibitors, alkaloid and oxalate respectively. Based on results of this study, cassava peel can be potential source of energy; however, protein and amino acids contents are very low. It is therefore, recommended that feeding of animal with cassava peel based diets be supplemented with good quality amino acids.
 
 
 La composition immédiate, l'acide aminé, la teneur minérale et phytochimique de la peau de manioc ont été déterminées. Les pelures contenaient 8,70 % d'humidité, 4,89 % de protéines brutes, 8,75 % de fibres brutes, 2,15 % de matières grasses brutes, 8,93 % de cendres. L'extrait sans azote et les valeurs énergétiques métabolisables étaient respectivement de 66,56 % et 2 717,96 kcal. Les résultats de la teneur en acides aminés ont révélé que l'histidine et la tyrosine sont l'acide aminé le plus limitant avec des valeurs de 0,005% chacune. Les acides aminés essentiels tels que la lysine, la leucine, la méthionine et l'isoleucine avec des valeurs de 0,032, 0,067, 0,076 et 0,070% étaient faibles. Le profil minéral a indiqué que le magnésium (913.74mg/kg) et le fer (111.50mg/kg) sont des minéraux les plus abondants. Les concentrations de produits phytochimiques étaient de 26,06, 699,8, 0,063, 24,81,8,37,1457mg/100g et 2,84 pour la saponine, le tanin, le cyanure d'hydrogène, le phytate, les inhibiteurs de la trypsine, l'alcaloïde et l'oxalate respectivement. D'après les résultats de cette étude, la peau de manioc peut être une source potentielle d'énergie ; cependant, la teneur en protéines et en acides aminés est très faible. Il est donc recommandé que l'alimentation des animaux avec des régimes à base de pelures de manioc soit complétée par des acides aminés de bonne qualité.

Culinary quality and sensory profile of cassava varieties harvested at different ages

Sweet cassava must be rapidly cooked and meet the sensory and technological requirements of consumers. The objectives of this study were to evaluate the culinary quality of sweet cassava varieties harvested at three ages and obtain the sensory profile of these varieties using the check-all-that-apply method (CATA). Roots of three cassava varieties released or recommended by Embrapa (BRS Aipim Brasil, BRS Dourada and Saracura) and the commercial variety Eucalipto, harvested at nine, 12 and 15 months of age, were evaluated for physical, chemical and sensory aspects. At nine months of age, the Saracura, BRS Aipim Brasil and BRS Dourada varieties did not differ in cooking time, averaging 41.62 min. The Eucalipto variety had similar cooking times at the three harvest ages, averaging 21.83 min. There was a difference between the four varieties at nine months, with Saracura exhibiting the lowest acceptance score (5.0) and differing from the Eucalipto variety, which showed an average score of 6.3. At 12 months of age, there was a significant increase in the acceptance of the Saracura and BRS Aipim Brasil varieties, which did not differ from Eucalipto and had an average score of 6.4. Consumers perceived differences between the sensory characteristics of the cassava varieties using CATA. The sensory terms “creamy”, “soft” and “sticky” can be associated with greater acceptance of cooked cassava roots, whereas terms such as “floury”, “slightly bitter”, “no taste”, “hard” and “fibrous” can be associated with less acceptance and are therefore undesirable from the consumer’s point of view. Principal component analysis showed that the age at which the roots were harvested had a great effect on the culinary quality of cassava, regardless of the evaluated variety. The commercial variety Eucalipto was well-accepted by the consumers irrespective of root age and can be harvested at any of the evaluated ages. For the Saracura, BRS Aipim Brasil and BRS Dourada varieties, harvesting is recommended at 12 or 15 months so that better quality roots are obtained.

Effect of soil amendments on leaf pigmentation and N status in cassava (Manihot esculenta crantz) grown in crude oil contaminated soil

Growth studies on TMS 30572, NR8082 and Local cassava cultivars grown on previously crude oil polluted soil were conducted to assess effects of oil palm bunch ash (OPBA), dried poultry manure (DPM) on Leaf pigmentation and N2 status of test crops. In addition, physical and chemical properties of soils were determined. The pH was raised from 5.62±1.50 in control soil to values that ranged between 6.97±1.23 to 9.24±1.89 in soil treated with organic amendment. The result of organic amendment ensures reduction of C: N ratio from 50:1 in control to critical threshold that ranged between 8:1 – 10:1 for improved decomposition and soil quality. SPAD measurement revealed no significance (P≤ 0.05) in readings for both treatments and control experiments. However, the interactive effect of both cassava variety and type of amendments were significant. Cultivar TMS 30572 was found to be brought to high productivity under treatment with combined OPBA + DPM and recorded highest chlorophyll content per unit area of leaf surface with Chl. a/Chl.b ratio of 2.13 and thicker leaf blade. While Leaf chlorophyll is directly associated with the efficiency and capacity of the photosynthetic apparatus and hence chlorophyll content in this study was found to be directly related to good health status of the test crops. Results revealed that quality of crude oil contaminated soil was greatly enhanced by organic amendment.

Weed cloth, an option for integrated weed management for short‐duration cassava

AbstractWeeds, a major constraint in cassava (Manihot esculenta Crantz), cause 45–75% yield loss. Weed management in short‐duration cassava is unexplored. Field experiment was conducted during 2013–2015 at ICAR‐Central Tuber Crops Research Institute (CTCRI), Kerala, India, in a split‐plot design. Main plots comprised three short‐duration cassava varieties (H‐165, Sree Vijaya, and Vellayani Hraswa) and subplots five weed control methods, chemical (using pre‐emergence herbicide, oxyfluorfen at 0.2 kg a.i. ha−1 on the day of planting), mulching with crop residues and green manure, weed control ground cover cloth (WCGCC), hand‐weeded, and unweeded controls. Weed flora was dominated by broad‐leaved weeds, hog weed or red spiderling (Boerhavia diffusa L.), colored fleabane (Vernonia cinerea L.), red tassel flower [Emilia sonchifolia (L.)], Asian spiderflower or tick weed (Cleome viscosa L.) and the nutsedge (Cyperus rotundus L.), which were absent under WCGCC. Plant height, stem girth, leaf production, tuber biomass, total biomass, crop growth rate, and tuber yield under WCGCC and chemical treatment were greater. The yield under WCGCC was 35 and 15% greater than hand‐weeding and chemical methods, respectively. The yield in chemical method was 17% greater than hand‐weeding. Combination of crop residues and green manuring were alternatives to chemical and handweeding methods. Unrestricted weed growth reduced yield by 74% over hand‐weeding. Weed index was lowest in WCGCC, but similar to chemical and eco‐friendly practices. Chemical method generated highest net income and benefit/cost ratio (US$3,315 and 3.4, respectively). The WCGCC, pre‐emergence herbicide, and biomass mulching can be components of integrated weed management in cassava.

Detoxification and nutritional enrichment of cassava waste pulp using Rhizopus oligosporus and Aspergillus niger

The present study evaluated the detoxification and nutritional enrichment potentials of the fermented cassava waste pulp obtained through different processing methods of sweet (S) and bitter (B) cassava varieties by fermentation with Rhizopus oligosporus and Aspergillus niger. Four batches [two with both bark and cortex of the tuber removed (S- and B-), two with bark only removed (S+ and B+)] of cassava waste pulp (CWP) were produced from each of S and B varieties. CWP from the four treatments were then subjected to Rhizopus oligosporus, Aspergillus niger, and natural fermentation. Cyanide (mg HCN/kg), phytate (mg/100g), tannin (mg/100g), pH, crude protein (N X6.25) (%), ash (%), Fe, P, K and Ca (mg/100g) content of the unfermented and fermented CWP were determined using standard procedures. The range of the reduction (%) in cyanide content for Rhizopus oligosporus fermented CWP (RCWP), Aspergillus niger fermented CWP (ACWP), and naturally fermented CWP (NCWP) were 86.24 – 91.95, 79.68 – 84.34 and 72.96 – 78.58 while those for phytate were 58.82 – 71.20, 29.98 – 39.26 and 36.16 – 40.32 respectively. Fermentation had no significant (p>0.05) effect on the tannin content while the pH range of NCWP, RCWP and ACWP were 7.20 – 7.50, 5.41 – 6.40, and 3.83 – 4.21, respectively. The range of the increase (%) in the protein content for NCWP, RCWP, and ACWP was 346 – 375 , 671 – 728 and 508 – 542 while those of the ash content were 7.16 – 7.91, 6.72 – 6.84, and 5.42 – 5.63 respectively. Of all the examined minerals, only calcium increased by 5.68 – 26.89, 49.96 - 70.43, and 59.71 – 98.87 % in NCWP, RCWP, and ACWP respectively. Results from the present study are indicating that controlled fermentation offers greater benefit over natural fermentation and that the cassava variety and not the peeling method will determine the extent of detoxification and nutrient enrichment.

Contribution of cassava and cassava-based products to food and nutrition security in Migori County, Kenya

The promotion of cassava as a staple and food security crop is widespread in Africa,Kenya included. Overreliance on cassava as a sole energy provider could lead to malnutrition. Consumption of high hydro-cyanide levels from cassava products could lead to health complications for consumers.This study sought to establish the contribution of cassava consumption to nutrition in Migori County.A cross-sectional survey was carried out and data collected on households’cassava production and consumption practices. Two hundred and fifty-three households were randomly selected and household farming heads interviewed in West Kanyamkago, Orango Central and Kamgundho locations as areas where cassava is predominantly grown. Seven cassava flour samples of different cassava varieties grown in the area were obtained from farmers.Analyses were done to determine the moisture, cyanide and protein contents on flour and cooked stiff porridge (ugali). Results indicated that 99.1% of the households were farming. They highly depended on sale of farm and livestock produce as income.Ninety four percent of the households consumed cassava,of which 88.4% produced cassava on their farms. The most preferred cassava variety was ‘Rateng’.The main cassava products consumed were ugali(stiff porridge)and porridge. Majority of the households (95%) never consumed cassava leaves and were not aware that cassava leaves could be consumed.The cyanide level on average on dry flours was 53.23mg/kg while on consumed cooked ugali was13.44mg/kg. These levels were above the maximum limit of 10mg/kg recommended by WHO.Low average protein levels of <0.5g/100g were observed in the cooked ugali. This could pose a danger of protein energy malnutrition if no other sources are consumed by the household members.Cassava farming households in the study area require support to promote growth of low cyanide varieties in order to reduce intake.

The physical properties of dried-growol produced with different cassava varieties and fermentation time

Growol is a staple food made from cassava and obtained through fermentation process. It is usually produced under 2-3 days fermentation and has been observed to have an intermediate moisture content, so it needs to be dried preserved. The purposed of this study was to evaluate the chemical characteristics of fermented cassava as well as the physical attributes of dried-growol produced using different cassava varieties and fermentation time. This study used local cassava varieties: Martapura, Meni, Ketan, and Lanting; while the fermentation durations were 2 and 4 days. Each variety of fermented cassava was analyzed for moisture content, starch, and amylose and then was steamed for 15 minutes. The fresh growols were dried at 50°C until the moisture content was approximately 10% and then the dried-growols were determined their texture and color. The results showed that cassava variety and fermentation time affected the chemical properties of the fermented cassava as well as the physical attributes of dried-growol. Moreover, the starch content of fermented cassava was found to be between 18.25-34.03% with the highest indicated in Martapura; while amylose content was between 7.50-18.30%. Martapura was observed to have a bright color and a little hard texture.

Analysis of the Protein Profile of Cassava Plantlets (Manihot esculenta Crantz.) Resistance to Fusarium Wilt Disease

Fusarium wilt disease is still a production constraint in Cassava (Manihot esculenta Crantz.) cultivation. The disease is caused by the fungus Fusarium oxysporum (Fo), which to date has not been cured. It is expected that the use of varieties of cassava that are resistant to Fusarium wilt is an important alternative for disease control. Induced Resistance cassava research on Murashige and Skoog medium containing Fusaric Acid (FA) selective concentration has been done before and there were indications FA concentration tolerant to the selection of resistant plantlets in vitro. It is hoped that cassava plantlets that are resistant to FA will also be resistant to Fo. In previous studies, the inoculation of Fo fungal isolates on resistant cassava plantlets was carried out in vitro, followed by DNA pattern analysis compared to controls. The results of the DNA pattern analysis, in the form of a new (specific) DNA band that has a size of 550 bp (OPA_1) and 300 bp (OPA_10), are predicted to be candidates for RAPD markers for cassava resistance to Fo. Based on the results of these previous studies, it is necessary to study more deeply in this study to ascertain whether the new DNA strand is really a peroxidase protein that causes cassava plantlets to be resistant to Fo by protein profile analysis. The results of protein profile analysis showed that the appearance of new protein bands (around 98 kD) indicated the formation of PR-protein (peroxidase) in cassava plantlets that were resistant to Fo and missing protein bands (around 65 kD) in cassava plantlets.

English

The use of cassava and sweet potato separately as raw materials for ethanol production in the recent past has been demonstrated. The search for the optimum processing conditions to hydrolyse and ferment sugars from the starches in cassava and sweet potato is well studied. The effects of substrate, temperature, enzyme types and concentrations, the reaction times of saccharification and fermentation were investigated for effect on ethanol yield. The objective of this work was to combine cassava and sweet potato as raw material to optimise the yield of ethanol for the combination. Selected cassava and sweet potato varieties were cultivated and harvested after 10 and 3 months, respectively. Liquefaction, saccharification and fermentation were carried out with Liquozyme SC DS, a combination of Spirizyme Fuel and Viscozyme L and Bio-Ferm XR (Lallemand) yeast, respectively. The combinations of cassava and sweet potato flours yield more ethanol than processing cassava and sweet potato flours separately. The best combination ratio of cassava and sweet potato, 1:1, resulted in the optimal ethanol yield of 16.2% v/v.   Key words: Cassava, sweet potato, optimization, ethanol yield, combination.

Adoption of improved cassava varieties in Nigeria: Insights from DNA fingerprinting versus self-reporting varietal identification approaches

Much of the empirical studies on crop varietal adoption in Sub-Saharan Africa relied on self-reported adoption in farm-household surveys, which is prone to measurement errors. In addition, farmers’ perceptions of consumption-related varietal traits in adoption studies has received limited attention compared with production-related traits. Using DNA-based and self-reported adoption measures, we analyze the adoption of improved cassava varieties (ICVs) with a focus on the extent of varietal misidentification, the sensitivity of the drivers of adoption to varietal misidentification and the role of farmers’ perceptions of biofortification trait in adoption decisions. We find that the adoption rate of ICVs is relatively high using both DNA-based and self-reported adoption measures, but there is notable misclassification in varietal adoption. We find that the mismatch in DNA-based and self-reported adoption measures leads to some variation in the factors that influence the likelihood and intensity of adoption of ICVs. This suggests that appropriate varietal identification helps in better understanding of the drivers of adoption. In addition, we find that despite the observed varietal misclassification, farmers’ perceptions of biofortification trait is significantly correlated with the probability and intensity of adoption of ICVs using both DNA-based and self-reported varietal identification. This suggests that inclusion of biofortification trait in cassava matters for both the likelihood and extent of adoption of ICVs. The latter lends credence to the emerging policy interests in breeding programs for biofortified crops to address hidden hunger in Nigeria.

Weed Interference on Growth and Leaf Nutrient Accumulation in Two Cassava Varieties

The development of cassava varieties with more efficient nutrient absorption can prevent losses caused by weed competition. The objective of this study was to evaluate dry matter accumulation and leaf nutrient content in traditional and improved cassava varieties, with and without coexistence with weeds throughout the cycle. A randomized complete block design was used in a 2 x 2 x 11 factorial scheme with four replications. The first factor consisted of two varieties (Baianinha and Clone 56-03); the second factor was composed of the conditions with and without coexistence with weeds, and the third factor was 11 harvest periods. Coexistence with weeds reduced leaf contents of N (20.8% and 24.8%), P (26.7% and 4.6%) and K (27.1% and 12.6%) for 'Baianinha' and 'Clone 56-03', respectively. For coexistence with 'Baianinha', the period up to the maximum daily nutrient accumulation rate (N, P and K) ranged from 82 to 99 days after planting (DAP), while for 'Clone 56-03', coexistence in this period ranged from 80 to 88 DAP. The plants from the variety 'Clone 56-03' presented higher total dry mass and root dry mass accumulation, as well as higher leaf contents of N, P and K than the traditional cassava variety 'Baianinha', especially when in coexistence with weeds during the whole cycle.

Composition of Two Local Cassava Varieties and the Effect of Processing on their Hydrocyanic Acid Content and Nutrient Digestibility by the Rat

Two common Nigerian cassava varieties Were subjected to proximate analysis with a view to assessing the relative potential nutrient composition of the roots, stems, leaves and seeds. The results obtained showed that the leaves, seeds and stems in that order are much richer than the roots in protein but higher in crude fibre. There was a relationship between the crude protein contents of the roots and stem and the hydrocyanic acid (HCN) content of the plant while that of the leaves and seeds did not appear to follow the same trend. HCN of the bitter cassava variety was considerably higher in the whole tuber, pulp and peel than in the sweet strain, sundrying and ensiling resulted in appreciable losses of HCN. Grated root lost about half its HCN content within six hours while stored whole roots showed a rapid decline in HCN from the fifth day after harvest. Apparent digestibility coefficients (A.D.C.) of the major nutrients of cassava roots were not significantly (P <0.05) affected by the processes of boiling or sundrying.

Availability of cassava residues and by-products for goat production in cassava based farming system

A study was carried out to investigate into the availability of cassava residues and by products and the utilization of the residues for goat production in Odeda local government area of Ogun state. Data was collected through a structured questionnaire coupled with occasional farm visits and personal interviews, from the farmers involved in the production of goats and cassava. Results showed that cassava is a major crop in the area and the cultivation of different cassava varieties is common. Cassava leaves, peels and sieviate were the common residues and by-products available and most farmers used these residues to feed their goats. The response of goats to cassava residues based diets was investigated using sixteen (16) West African dwarf goats, aged 4 to 6 months with average body weight of 6.5kg in a completely randomized design. The four treatments used namely (diets A to D) contained varying levels of cassava leaves, peels and sieviate and were repli performance increased (P < 0.05) with increasing level of cassava leaves in the diets. Weight gain of goats ranged from 30.02 to 37.85g/day across the dietary treatments. In conclusion, cassava residues are readily available in the study area and the response of goats fed diet C consisting 50% cassava leaves, 30% cassava peels and 20% cassava sieviate produced the best performance in terms of feed intake, digestibility and weight gain. This can therefore be recommended as best combination strategy in making use of cassava residues in goat feeding in Nigeria.