African Crop Science Journal

Caracteristiques des systemes de culture a base d’anacardier dans les zones de production de l’anacarde de la Côte D’Ivoire

A.K.Y.C. Letto

L’anacardier (Anacardium occidentale L.) est un arbre aux intérêts multiples et variés, qui contribue au développement socio-économique de la Côte d’Ivoire. Si les premières plantations étaient destinées à lutter contre la dégradation de l’environnement dans les régions de savane, l’anacarde est aujourd’hui devenu une véritable culture de rente dans le pays. L’objectif de cette étude était de caractériser les systèmes de culture à base d’anacardier (caractéristiques sociales et agronomiques) en Côte d’Ivoire, en vue de favoriser leur amélioration. Pour ce faire, une enquête a été menée auprès de 1182 producteurs d’anacarde, répartis dans quatre zones de production (Centre, Nord, Nord-Est et Nord-Ouest). Les résultats ont montré que les producteurs d’anacarde sont majoritairement des exploitants dont la moyenne d’âge est comprise entre 45 et 50 ans, avec une prédominance d’hommes. La plupart des producteurs pratiquent la rotation des combinaisons de cultures au stade juvénile des arbres (< 10 ans). En outre, les rotations de cultures varient selon les zones agro-écologiques. Globalement, les céréales sont la principale culture dans les rotations dans le Nord (67,5%) et le Nord-Ouest (74,8%), avec une prédominance du maïs. En revanche, les tubercules, avec l’igname en tête, dominent les rotations dans les zones du Centre (59,8 %) et du Nord-Est (78,8 %) du pays.

Déterminants socio-économiques de la production de lentille de terre [Macrotyloma geocarpum (Harms) Maréchal & Baudet] au Bénin

P.V. Vissoh

La lentille de terre (Macrotyloma geocarpum) est une légumineuse populaire au Bénin, dont le niveau de production est resté stagnant, voire en légère baisse au cours de la dernière décennie. L’objectif de cette étude était d’analyser les déterminants socio-économiques et culturels de la production de M. geocarpum au Bénin. Une enquête a été menée au moyen de discussions de groupe et d’entretiens individuels sur un échantillon de 103 producteurs de lentille de terre identifiés grâce à l’approche d’échantillonnage « boule de neige » à travers 21 villages répartis dans cinq communes productrices du département du Zou. Il a été observé que la production de la lentille de terre était déterminée principalement par l’âge, le sexe, la classe sociale, la distance de la maison au champ, le soutien de la vulgarisation, le groupe ethnique et la superficie emblavée pour la production. D’autre part, l’abandon de la production était principalement dû à un accès et un contrôle limité des ressources par les femmes ; accès limité à l’éducation et non-implication des femmes dans les instances de prise de décision ; les variations climatiques, la pénurie de main-d’œuvre occasionnelle et le manque de soutien financier à la production.

Production of indigenous mushrooms spawn using crop residues as substrates

P.W. Njeru

Indigenous oyster mushrooms occur naturally when conditions are favourable. Achieving good quality spawn is a major challenge to small-scale farmers in Kenya, who strive to domesticate indigenous mushrooms. The use of wheat grain in mushroom growing industries for spawn production poses a threat to food security. The objective of this study was to evaluate crop residues as alternative substrates for indigenous mushrooms spawn production in Kenya. Different crop residues, including straws of wheat, barley and beans, maize cobs and sawdust were sterilised and tested for spawn production. Colonisation, pinning and mushroom yields were evaluated on bean and wheat straw substrates. There was a significant difference (P<0.05) in mycelia colonisation period when different spawn types were inoculated on bean and wheat straw substrates. Bean straw spawn had the shortest colonisation period (23 days) and was the best agricultural waste spawn. There was no significant difference (P<0.05) on pinning days and 2nd flush yields for the different types of spawn. There was a significant difference (P<0.05) between maize cob and wheat grain spawn in 1st flush yields. Bean straw spawn had a flush 1 yield of 125.2 g which, was not significant (P>0.05) compared to the wheat grain spawn (control) that gave a yield of 126.1 g. Results of this study indicate the suitability of various agricultural crop residues as alternative substrates for indigenous spawn production.

Occurrence of entomopathogenic nematodes (Steinernematidae, heterorhabditidae) as potential biocontrol agents against Spodoptera frugiperda infesting Zea mays

Y. Danso

Synthetic insecticides are used worldwide to manage invasive fall armyworm (Spodoptera frugiperda) in cereals, in spite of the chemical’s prohibitive cost and threats to environmental health. In Ghana, little attention has been given to entomopathogenic nematodes as insect pest biocontrol agents, due to the existence of dismal expertise in the field. This study evaluated maize (Zea mays L.) farms for endemic entomopathogenic nematodes as potential biological control agents against fall armyworms infesting maize in Ghana. Entomopathogenic nematode juveniles were extracted using an insect baiting technique, White traps. These Rhabditid nematodes (Heterorhabditis; Steinernema) were found in 75% of 200 soil samples; and 92.5% of 40 districts targeted by this study. The Greater Accra region recorded the greatest population density (1,820 juveniles per 5 fall armyworm larvae cadavers); while; the Central region recorded the lowest density (81 juveniles per 5 fall armyworm larvae cadavers). There was high presence of entomopathogenic nematodes across the study areas. Therefore, entomopathogenic nematodes offer a promising alternative strategy for managing fall armyworm infestation of maize in Ghana to minimise over-reliance on synthetic insecticides.

Cultural, morphological and pathogenic variability of Phytophthora colocasiae isolate from taro in Cameroon

E.B. Manju

There exist 124 species of Phytophthora worldwide that cause serious diseases in natural ecosystems. These species have been identified using molecular methods. This study was conducted to determine the cultural, morphological and pathogenic variability of isolates of P. colocasiae processed from cultivars of Taro from Cameroon.The study was conducted in three agroecological regions, namely, Yaoundé, Bambui and Ekona where the disease was prevalent. Morphology showed that the mycelia were circular on all the isolates, in the three study zones. Mycelia colours ranged from white to cotton white. The colours of the culture media, after inoculation and mycelia growth, were the same. There was a significant difference (P<0.05) in mycelial growth among the isolate; with the longest of 5.5 cm in V6 juice agar media. Spore morphology was either spherical or ovoid in all the Taro isolates, in all culture media, except water medium. All four isolates were pathogenic to the four cultivars of Taro, causing lesions on leaves on inoculation. The most virulent fungi isolates were L1 (dark green petiole with small leaves) and L2 (red petiole with small leaves), which caused the largest lesion (>10 mm) in Taro cultivars during 14 days of inoculation.

Genetic analysis of mode of inheritance of seed yield and its components in tropical soybean genotypes

I.S. Adetiloye

The decision related to efficient breeding methods depends largely on the understanding of the type of gene action controlling the expression of the characters to be selected. The objective of this study was to estimate the gene action controlling yield and components in soybean (Glycine max L. Merrill). The study involved six basic soybean generations (P1, P2, F1, F2, BC1 and BC2) of two crosses, i.e. cross I (TGx1987-62F × TGx1830-20E) and cross II (TGx1987-10F × TGx1740-2F), at the Research farm of the International Institute for Tropical Agriculture, IITA, Ibadan. Data were subjected to generation mean analysis to determine gene actions and interactions, using Hayman model. The results obtained from the individual scaling test A, B, C indicated that the simple additive-dominance model was inadequate to reveal the inheritance of the gene governing most traits. Non-allelic gene interaction was crucial in the inheritance of most studied traits. The Hayman six-parameter genetic model demonstrated that the signs of [h] and [l] were contrasting for most of the traits; suggesting duplicate epistasis. In fact, the effect of dominance was important and significant in the genetic control of most of the traits studied. Therefore, improvement of soybean seed yield and its related characters need intensive selection and should be delayed until later generations.

Yield stability and relationships among parameters in maize

M.S. Abd El-Latif

Producing high yielding maize (Zea mays L.) hybrids well-adapted to many environments is the most important goal of the National Maize Research Program in Egypt. Genotype x environment interaction (GEI) continues to be a major challenging issue to plant breeders and production agronomists. The objective of this study was to identify maize hybrids with stable and high yield performance across different location under Egyptian conditions. Five yellow single crosses (SC Sk-149, SC Sk-150, SC Sk-151, SC Gm-111 and SC Gz-312); three red single crosses (SC Sk-1 Red, SC Sk-2 Red and SC Sk-3 Red); and two yellow commercial hybrids (SC 162 and SC 168) were evaluated at five sites in Egypt. Stability parameters for grain yield were performed to estimate both regression coefficient (bi), deviation from regression (S2di) and coefficient of determination (R2). Results showed that mean squares due to environments (E), hybrids (H) and their interaction (H × E) were significant, or highly significant for all traits. The best hybrids were SC Sk-3 Red for earliness, SC Gm-111 for highest plant; and SC Sk-149 and SC Sk-2 Red for resistance to late wilt disease. Superiority percentage for grain yield of two yellow promising crosses SC Gm-111 (22.78 and 19.69%) and SC Sk-150 (11.00 and 8.21%) were significantly out yielded the two checks SC 162 and SC 168, respectively. Four hybrids can be considered stable for grain yield based on the regression coefficient; as well as five hybrids based on deviation from regression and eight hybrids depending on coefficient of determination. Hybrids SC Sk-150 and SC Gm-111 had high grain yield and stable for R2. Mean grain yield was significant and positively correlated with S2di; but not significant with bi and R2. Also, R2 was significant and negatively correlated with S2di, but not significant with bi also bi or with S2di.

Gain and performance in yield and micronutrient concentration in common bean improvement

W. Amongi

Common bean (Phaseolus vulgaris L.) is a staple and nutritious leguminous food crop for all income categories in Africa. Efforts to improve its yield performance and nutritional components, especially iron and zinc have resulted in release of several varieties in the sub-Sahara African region. The objective of this study was to assess genetic progress in varieties released in 12 African countries through the Pan African Bean Research Alliance (PABRA) from 1973 to 2017, to inform current breeding decisions. A total of 214 released varieties, land races and breeding lines, of bush and climbing beans were evaluated for yield, micronutrient (Fe and Zn) concentration, and phenology in three locations (Kawanda and Kachwekano in Uganda, and Kitengule in Tanzania) in 2017/2018. There were significant differences (P<0.01) among genotypes for all traits, except days to maturity (DPM). Genotype x environment interaction was also significant (P<0.05) for all assessed traits, except for iron in climbing beans. Across environments, repeatability (H2) was greater than 0.50 for all traits, except for DPM in climbing beans. Annual rates of genetic yield gains were 4.41 and 4.57 kg ha-1 for large and small seed bush beans, and -2.74 and 21.6 kg ha-1 for large and small seeded climbers. Similarly, gains in seed iron (FESEED) were 0.40 and 0.17 ppm for bush and climbing beans, respectively. These represented an annual relative gain over the oldest varieties of 0.6 and 0.7% kg ha-1 for yield of large and small seeded bush beans, -0.3 and 1.6% kg ha-1 for yield of large and small seeded climbers, 0.6 and 0.2% ppm for FESEED of bush and climbers. Overall, genetic progress was slow for both yield and FESEED.

Socioeconomic evaluation of wild rice as famine food crop in Southern Darfur State, Sudan

M.M. Brika

Wild rice (Oryza barthii) is increasingly used in Sudan as a food crop. Wild rice is a whole grain, rich in minerals, vitamins, protein, starch, dietary fiber and various phytochemicals; and yet low in fat, with a beneficial fatty acids profile. The objective of this study was to evaluate the socioeconomic significance of wild rice as a famine food crop in Darfur state of Sudan. A study was conducted in five districts (Tullus, Gadad, Demso, Katila, and Umshtoor) in South Darfur in Sudan. Primary data were obtained through a face-to-face semi-questionnaire interview on 146 households; supplemented with interviews of key informants and group discussions. All respondents (100%) not only attested to knowing wild rice and its growth habits, but also consumption (93.8%) of the crop. Wild rice reportedly grows naturally and widely in valleys, although it was dismally exploited by the local population. It is harvested manually and traditionally; and sold mostly in the local markets, without post-harvest value additions. The crop is consumed in various meals, but mainly in the form of porridge. Some respondents (13%) used the crop in times of famine. Wild rice is stored in traditional containers (95.9%) for periods ranging from 8 to 12 years without visible storage problems.

State of knowledge of methodologies for establishing “typologies of production systems”

E. Oka

In sub-Saharan Africa, climatic hazards and land pressure have stimulated a search for production intensification methods, adapted to the various environments and types of farming, in a bid to ensure food security in the region. Indeed, this intensification is conditioned by the availability to farmers of innovations that are adapted to their constraints and priorities. Thus, the adaptation of innovations to the diversity of agricultural production systems requires establishment of typologies that reflect the heterogeneity of farms and make it possible to reduce diversity to a manageable scale. In this article, we reviewed the state of knowledge on methods for establishing “typologies of production systems”, based on existing knowledge, in order to examine the extent to which they enable understanding of this reality of the agricultural economy. Faced with current global challenges, such as population growth and climate change, sufficient food supplies and quality will require more efficient and robust production systems, based on good agricultural practices that ensure efficient use of the natural resource base, and within an enabling policy and institutional environment. Improving production systems for sustainability will, therefore, need to be based on the implementation of relevant recommendations derived from typologies built through science-based robust methodology, combining participatory approaches and quantitative and qualitative data analysis methods, “data mining”.