Genotype x environment interaction effects on native cassava starch quality and potential for starch use in the commercial sector

Cassava (Manihot esculenta Crantz) is the second most important staple food crop in sub-Saharan Africa, providing up to 285 calories per person per day. Cassava starch is a potentially important industrial material in Malawi. Industries hesitate to use cassava starch because the powder sold by some suppliers has been grossly inadequate. This study was conducted to evaluate native cassava starch qualities for different Malawi cassava genotypes, determine the appropriate stability parameter to deal with GxE for starch quality traits, and potential for use of cassava starch by the main industries in Malawi. Trials were conducted in Malawi to examine starch quality parameters, root dry mater and starch extraction. Based on the results, the moisture and ash content were much lower than the recommended allowable maximum. The pH for cassava starch was within the recommended range. Additive main effects and multiplicative interaction (AMMI) were strongly correlated with other stability parameters such as Wi-covalence and stability variance–no covariate. From the results, genotype has a greater influence on root dry matter than the environment. Native cassava starch can be used in the pharmaceutical, battery and packaging material making and textile industries in Malawi

Ethnobotany, morphology and genotyping of cassava germplasm from Malawi

The objectives of this study were to collect and characterise Malawian cassava germplasm using ethnobotany, morphological and Amplified Fragment Length Polymorphism (AFLP) markers. Exploration of accessions with the help of indigenous knowledge was done. Ninety three accessions collected from farmers fields and commercial programs were planted and morphologically characterised at Chitedze Agricultural Research Station (Malawi). A subsample of 28 accessions was used for DNA fingerprinting. Preferences of farmers for traits in cassava varieties were diverse according to use and areas. Ethnobotany revealed wide genetic diversity in the germplasm, as did morphological characterisation, but morphological characterisation failed to uniquely differentiate all analysed accessions. AFLP markers showed narrow genetic diversity but managed to distinguish all accessions. Hence, there is need to use all three techniques at different levels to identify genetic diversity

Aflatoxins contamination in processed cassava in Malawi and Zambia

Strains of the Aspergillusfungi, especially A.flavus and A. parasiticus,primarily produce aflatoxins which are a major health concern to man and livestock because of their acute and chronic health effects. Aflatoxins pose the greatest risk to health in tropical Africa because of their widespread prevalence and high toxicity; carcinogenic (cause liver and esophageal cancer)effect, immune system suppressing and anti-nutritional contaminants in many food commodities and even cause death. Aflatoxins havealsobeen reported to compromise vaccine efficacy in experimental animals. Due to the seriousness of aflatoxins, international agencies have restricted levels of aflatoxins to 20 ppb in food materials as the maximum permissible level in the United States and 4 ppb total aflatoxins and under 2 ppb aflatoxin B1 in Europe. These regulations directed at minimizing human exposure to aflatoxins results in severe economic loss to producers, processors and marketers of the contaminated crop.A study was conducted in Malawi and Zambiato assess the level of fungal and mycotoxins’contamination in commonly processed cassava products. A total of 92 and 88 samples of processed cassava productscomprisingmakaka, flour, kanyakaska, kadonoska, scrapes and grates were collected in the rainy season of 2008 and 2009in Malawi, respectively. Further,22 samples of processed cassava products comprising dried cassava chips and flour were collected in the rainyseason of 2009 in Zambia. The sampleswere analyzed for fungal and aflatoxins B1, B2, G1 and G2 contamination using the Romer mini-column method andthe VICAM AflaTest immunoaffinity fluorometric method.None of the samples in 2008 werecontaminated with aflatoxins. Similar results were obtained in 2009 with almost all the samplesin Malawi and Zambia having aflatoxinlevels much lower (<2.0?g/kg in Malawi and <4.2 ?g/kgin Zambia) than the Codex Alimentarius Commission (CAC) maximum permissible level of aflatoxins of 10.0 ?g/kg,implying that the cassava products analyzed were safe for human consumption. However, further studies are needed to covera larger sample size over a period of a year to represent all seasons in the cassavaproducing andconsuming areasandconclusively make certain the safety of these products for human consumption

Cassava and sweetpotato yield assessment in Malawi

Cassava (Manihot esculenta Crantz) and sweetpotato (Ipomoea batatas Lam) are important food and cash crops in Malawi. However, key information regarding varieties grown, sources of planting materials, post-harvest handling, utilisation and tuber yields is lacking. A study was, therefore, conducted to source this information. Farmers grow mostly local varieties of cassava with own gardens as the main source of planting materials. Several varieties of sweetpotato are grown with Kenya (SPN/O, bred in Tanzania) as the most popular. Sprouts from previous season\'s gardens are the main source of planting materials. Cassava and sweetpotato are grown for food and cash. However, in some area cassava stems are used for fuel wood. Most farmers do not store fresh cassava roots but process them into makaka, kanyakaska and kadonoska, or sell them fresh. Processing for sweetpotato is limited to boiling and roasting. Most farmers store sweetpotato, but this is constrained by the sweetpotato weevil damage and rotting. Root yield ranged from 13.1 to 31.4 t ha-1 for cassava, and 10.2 to 14.0 t ha-1 for sweetpotato. Except for Nkhata Bay, the yields of both crops were much lower than from research stations. Unavailability of acceptable improved varieties, high incidence of pests and diseases, and poor cultural practices are the main causes of low yields in the targeted areasLe manioc (Manihot esculenta Crantz) et la patate douce (Ipomoea batatas Lam) sont des importants aliments et plantes génératrices de ressources en Malawi. Cependant, l\'information clé concernant les variétés plantées, les sources de matériels de plantation, les manœuvres post-récoltes, l\'utilisation et les rendements de tubercules manque. Une étude était alors conduite pour approvisionner cette information. Les fermiers cultivent souvent les variétés locales de manioc avec comme source principale de matériels de plantation leurs propres champs. Plusieurs variétés de patate douce sont cultivées au Kenya (SPN/O, conditionnée en Tanzanie) comme le plus populaire. Les germes des champs de saison précédente sont la source principale de matériels de plantation. Le manioc et patate douce sont cultivés pour la nourriture et l\'argent. Cependant, dans certaines aires les tiges de manioc sont utilisées pour le bois de chauffe. La plus part des fermiers n\'entreposent pas les racines de manioc frais mais transforment les en makaka, kanyakaska et kadonoska, ou les vendent frais. La transformation de la patate douce est limitée à l\'ébullition et au rôtissage. La plus part des fermiers entreposent la patate douce, mais ceci est gêné par les dégâts et les avaries des charançons. Les rendements de racines ont variés de 13.1 a 13.4 t ha-1 pour la patate douce. A l\'exception de laurier Nkhata, les rendements des toutes les deux cultures étaient plus bas que ceux des stations de recherche. La non disponibilité des variétés améliorées acceptables, l\'incidence élevée des pestes et maladies, et les pauvres pratiques culturales sont les causes principales de faibles rendements dans les aires visées

Evaluation of commercially available herbicides for weed control in cassava

A trial was conducted in 2008/09 at Chitedze (31o 59' S; 33o 38' E) and Chitala (13o 40' S; 34o 15' E) Research stations in Malawi to evaluate commercially available pre-emergent herbicides for weed control in cassava (Manihot esculenta Crantz). Four herbicides, Bullet (chloroacetanilide, dimethanamid, triazine), Harness 90 EC (chloroacetanilide), Codal Gold 412-5 EC (prometryn and S-metolachlor) and Metalachlor 960 EC (S-metolachlor; acetamide), were evaluated with and without follow up hand-hoe weeding (check). Panicum maximum, Elusine indica, Rottboellia chochinchinensis and Setaria pumila were the common narrow-leaved weeds while Commelina benghalensis, Bidens pilosa, Nicandra physalodes and Acanthospermum hispidum were the common broad leaved weeds. Herbicide application did not affect crop establishment but significantly (P<0.001) reduced early weed growth by 74.8 to 91.2 % at Chitedze and 53.7 to 97.9 % at Chitala. Bullet was more effective in early weed control (2.8 weeds m-2 at Chitedze and 0.0 weeds m-2 at Chitala) than the other herbicides (38.7 weeds m-2 at Chitedze and 8.8 weeds m-2 at Chitala) and resulted in root yields (12.3 t ha-1 at Chitedze and 18.4 t ha-1 at Chitala) and returns (MK238,844.00 ha-1 at Chitedze and MK360,779.00 ha-1 at Chitala) comparable to or higher than hand weeding (root yield of 10.6 t ha-1 at Chitedze and 16.3 t ha-1 at Chitala and returns of MK2 0 1 , 4 3 8 . 0 0 h a - 1 a t Ch i t e d z e a n d MK310,448.00 ha-1 at Chitala) and other treatments (root yield of 2.2-13.1 t ha-1 at Chitedze and 1.3-23.6 t ha-1 at Chitala and returns of MK44,000.00 to MK249,078 at Chitedze and MK26,000.00 to MK465,100 ha-1 at Chitala), making it a potential alternative to hand hoe weeding in cassava

Economic losses experienced by smallscale farmers in Malawi due to cassava brown streak virus disease

Cassava is an important root crop in Malawi. It is the second most important food crop after maize. It is grown throughout the country as a food security crop, sack/cash crop, and as a staple food crop along the Lake Malawi. Is is a staple for over 39 % of the country&rsquo;s population. Farmers are not benefiting as much as they might from cassava because they are faced with a number of constraints. These include: - inherent low yielding and late maturing local cultivars - pests and diseases prevalent in the country - low promotion of good cultural practices. The major pests and diseases of cassava in Malawi are, cassava mosaic virus disease (CMD), cassava bacterial blight (CBB), cassava brown streak virus disease (CBSD), cassava green mite (CGM), cassava mealy bug (CM) and termites. The objective of this study was to determine the economic impact of CBSD on the farmers in Malawi where the disease is prevalent. The paper makes the following recommendations: - the cassava research organisations should mount urgent awareness campaigns of the disease and its management for both extension agents and farmers - the cassava research organisations should establish effective collaboration with the extension system on matters of proper cassava husbandry to effectively and efficiently control the disease - they should additionally carry out local collection exercises for cultivars that show CBSD disease resistance in the high disease pressure areas - there is an urgent need for cassava research and extension organisations to multiply cultivars and promising clones that have shown multiple disease resistance and that are widely accepted by farmers for distribution in the heavily affected areas - in collaboration with entrepreneurs, these organisations need to develop and strengthen sustainable seed multiplication and distribution systems as a way of assuring the provision of clean planting material

CH92/082 and TME 6 cassava clones officially released for farmer growing in Malawi

Cassava clones CH92/082, TME 6 and BA95/070 were evaluated against Mbundumali, Phoso, Mulola and Sauti as checks. These clones were evaluated at Makoka, Mkondezi, Baka and Kasinthula Research Stations that represented different agro ecologies and in Mzuzu ADD under farmers' conditions. The objective of cassava improvement programme in Malawi is to develop cassava varieties that are: high yielding per unit area of land; tolerant to major diseases (cassava mosaic disease and cassava brown streak disease) and pests (cassava green mite and cassava mealy bug), adaptable to local environmental conditions and acceptable by end-users