African Crop Science Journal

Cassava mosaic disease and abundance of its whitefly vector in north-western Democratic Republic of Congo

2023-12-05T16:46:55+00:00

Cassava mosaic disease (CMD) is rampant in the Democratic Republic of Congo (DRC). The objective of this study was to assess the significance of CMD and abundance of its whitefly (Bemisia tabaci) vector, in the North-Western provinces of the DRC. A field study was conducted in three provinces, namely Mongala, North Ubangi, and South Ubangi, of north-western DRC, during February to March 2022. One hundred cassava (Manihot esculenta Crantz) fields, aged 3 to 9 months and at intervals of about 10 Km apart, were prospected during an epidemiological survey of cassava mosaic disease. The cassava cropping system (pure culture or intercropped), and the epidemiological parameters of cassava mosaic disease (incidence, severity of CMD, abundance of whiteflies, sources of infection) were assessed. Results showed that the prevalence of CMD and abundance of whitefly vectors in DRC were significantly different among the three provinces. The incidence was low in South-Ubangi (16.49%), medium in Mongala (21.83%), and high in North-Ubangi (44.63%). The severity of the disease in north-western DR Congo is very low and remains below level a value of 3 in all the provinces covered by this study. Whitefly abundance fluctuated between 1.49 (South-Ubangi) to 5.74 (Mongala). Infected cuttings were the main source of CMD infection in all the provinces. Cassava cultivated in monoculture had the highest populations of this victory.

Morpho-phenological characteristics of exotic pigeon pea genotypes in western Burkina Faso

2023-12-05T16:58:40+00:00

Pigeon pea (Cajanus cajan L.) is an important legume and multi-use crop, which contributes to food and nutritional security in sub-Saharan Africa (SSA). This crop, however, remains less popular and is thus underutilised in west Africa. The objective of this study was to characterise the morphological and phenological features of exotic pigeon pea genotypes in western Burkina Faso in order to provide an entry point for the breeding programme. The study was conducted at two sites, namely Farakoba and Kouentou, located in western Burkina Faso, involved seven exotic genotypes, namely ICP-15029, ICP-14722, ICP-8863, ICPL-20338, ICPH-2740, ICPH-2438 and ICPL-20092, sourced from ICRISAT, India. Also, two local accessions (FKB Cc1 and FKB Cc2) were included as controls. Results showed that semi-spreading (80% of the genotypes) and indeterminate growth habit (80% of the genotypes) were dominant in the genetic materials, with regards to branching pattern and growth habit, respectively. The genotypes including the two checks, were distinguished by three seed colours, viz. brown (three genotypes), dark brown (four genotypes) and grey (two genotypes). There were highly significant differences among the genotypes for phenological (P<0.001) and morphological (P<0.001) traits. The earliest genotype to flower at both sites was ICPL-20338; while the latest was ICPL-20092. A principal component analysis based on the quantitative traits showed that the first two PCs explained 91.78% of the total variation among the genotypes. The most significant contributor traits were stem diameter, leaf size, 50% flowering and plant height. Cluster analysis grouped the genotypes into five clusters.

Mode of inheritance of rice resistance to African rice gall midge

2023-12-05T17:12:09+00:00

Development of rice (Oryza sativa) varieties with improved traits, like resistance to both biotic and abiotic stresses, is crucial, particularly for sub-Saharan Africa (SSA). Among the biotic stresses, the African rice gall midge (Orseolia oryzivora) is one of the most devastating pests/insects of rice in the region. The objective of this study was to determine the mode of inheritance of resistance to African rice gall midge (AfRGM) as a basis for developing insect resistant rice varieties in the SSA. Four resistant genotypes and four susceptible locally adapted genotypes of rice were crossed in half diallel crossing design. The F2 segregants and their corresponding parents, were evaluated in the cage experiment, against AfRGM in a 4 by 9 alpha lattice design, in three replications. Results showed a significant variation (P<0.05) in rice AfRGM resistance among genotypes. Significant general and specific combining abilities were observed, indicating that both additive and non-additive gene effects were important in rice AfRGM resistance. However, the non-additive effects predominated at 42 and 63 days after infection (DAI). High coefficients of genetic determination in the broad sense (0.96, 0.97 and 0.98, respectively), and moderate narrow sense (0.55, 0.45 and 0.39) at 21, 42 and 63 DAI, were obtained, with a moderate Baker’s ratio of 0.57, 0.46 and 0.40 in the 21, 42 and 63 DAI, respectively; indicating primarily non-additive inheritance among crosses.

Diallel analysis of maize inbred lines for estimating superiority and combining ability

2023-12-05T17:31:02+00:00

The phenomenon of heterosis has provided the most important genetic tools for crop yield improvement. Identification of specific parental combinations capable of producing the highest level of heterotic effects in F1 has immense value for commercial exploitation of heterosis. The objective of this study was to assess the combining ability variances and superiority in twenty one combinations developed by crossing seven maize (Zea mays L.) inbred lines in half diallel fashion design. The resulting 21 hybrids, along with two check hybrids, were evaluated in Randomised Complete Block Design, in three locations during 2022 season in Egypt. The results showed that both additive and non-additive gene actions were important in controlling all the measured traits. The General Combining Ability (GCA) variance was found to be greater than Specific Combining Ability (SCA) variance, indicating predominance of additive and additive by additive gene effects in the inheritance for all studied traits. Cross P2×P3 significantly out yielded the best check (SC. 168) for the grain yield trait. The parental inbred lines, P1, P2 and P3, possessed significant desirable (GCA) effects for the grain yield trait. The cross combinations (P1×P5),(P2×P7), (P3×P7),(P4×P5),(P4×P6) and (P6×P7) showed significant positive sca effects for grain yield. Cross P2×P3 (10.32**) obtained superiority (%) relative to the check hybrid SC.168 for grain yield. On the other hand, five crosses viz. (P1×P3), (P1×P5), (P2×P3), (P2×P5) and (P3×P5) expressed positive superiority (%) over the check hybrid SC.3444 for same trait. Thus, these crosses could be recommended to be released as commercial hybrids by Maize Research Programme after further evaluation and testing in multi-locations in Egypt.

Agronomic performance of maize hybrids under Aspergillus flavus inoculation in Cameroon

2023-12-05T17:39:05+00:00

Maize (Zea mays L.) is a major staple crop in most of the sub-Sahara Africa (SSA) region, constrained by a multitude of plant diseases, with the ear and kernel rots being the most widespread and difficult to manage on maize. The objective of this study was to access the agronomic performance of F1 maize hybrids exposed to Aspergillus flavus, under different agro-ecological conditions, in Cameroon. A total of 120 genotypes of maize, including four commercial hybrids, were evaluated under A. flavus infection at two sites; namely Bangangte in the Western Highlands and Mbalmayo, in the Bimodal Humid Forest Zone of Cameroon. The study was conducted during 2020 - 2021 cropping seasons. Results revealed that at Bangangte site, six (89343X88094, 88099X88094, 90204XExp 124, 89246X87036, TZI-5-1171XExp 124 and 90219X1368) out of the top 20 high yielding hybrids, had significantly high (p<0.001 tolerance (0% severity) to Aspergillus ear rot infection. At Mbalmayo site, eight (8923X88094, TZI-5-1171XExp124, 89343X88094, 90219X87036, 89243X87036, 87014X88094, TZSTR1150X87036 and 89248X88094) out of the top 20 high yielding hybrids also showed significant high (P<0.001) tolerance (0% severity) to Aspergillus ear rot infection. The interaction between hybrids and location was significant (P<0.05) for all measured traits, except ear height, grain texture, ear insect damage and husk cover (P>0.05). The pooled broad sense heritability of hybrids in the two locations varied from 5% for grain texture to 92% for days to 50% physiological maturity. Grain yield was negatively correlated with Aspergillus ear rot disease incidence and severity. Hence, promising high yielding maize hybrids with appreciable tolerance to Aspergillus ear rot disease could be selected among the tested genotypes.

Effect of intercropping on potato bacterial wilt disease and tuber yield in Kenya

2023-12-05T17:54:38+00:00

Potato (Solanum tuberosum L.) is a major tuber crop in Kenya, whose productivity is heavily impaired by bacterial wilt disease, caused by Ralstonia solanacearum (Smith). Existing management strategies have not been effective, owing to the diversity and robustness of the pathogen and variation in the host range. The objective of this study was to evaluate the effectiveness of intercropping on the incidence of bacterial wilt and yield of potato in Kenya. A field experiment was conducted in four potato-growing counties, namely; Nyandarua, Nakuru, Bomet and Bungoma in Kenya. Treatments included intercroping with spring onion (Allium fistulosum L.); garden pea (Pisum sativum L.); and cabbage (Brassica oleracea var. capitata L.). Treatments also included a pure stand of potato as the control. Generally, intercropping had a significant suppressive effect (P<0.05) on the incidence and severity of bacterial wilt disease. Intercropping potato with spring onion, in particular, had the highest disease suppressive effect, followed by intercropping potato with cabbage; and lastly by potato with garden pea. Accordingly, potato-onion intercrop recorded the highest potato tuber yield (12.9 t ha-1), while the potato pure stand recorded the lowest tuber yield (7.9 t ha-1). Bacterial wilt disease incidence positively correlated with disease severity (r = 0.931; P<0.05). In contrast, the disease incidence and severity negatively correlated with tuber yield. In terms of Land Equivalent Ratio (LER), the highest value (1.64) was with potato-onion intercrop; and the lowest (1.35) with the potato-garden pea intercrop.

Influence du charbon actif sur la callogenese des feuilles immatures du palmier a huile

2023-12-05T18:04:21+00:00

La production in vitro de plants issus de cultures tissulaires est un moyen de production massive des plants végétatifs exempts de maladies en vue d’une production commerciale rapide de jeunes plants de palmiers à huile (Elaeis gumeensis Jacquin.) en Afrique de l’Ouest. Cependant, ces dernières années, on a observé un arrêt croissant du taux de multiplication des cals et de la production d’embryons à partir des cals régulièrement induits. L’objectif de cette étude a été d’étudier l’efficacité de la granulométrie du charbon actif sur l’induction des cals chez des vitro plants de palmier à huile (Elaeis gumeensis Jacquin.). Les feuilles immatures de palmier à huile ont été désinfectées et mis en culture sur les milieux 164, 166 et 034. A ces milieux de culture, cinq lots de 2000 mg l-1 chacun, de charbon actif (1 = 36f0719, 2 = 54H0545, 3 = 03120, 4 = 20K0244 et 5 = 129H0017) ont été additionnés à l’exception le milieu 034, qui est le contrôle. Les résultats révèlent que le charbon actif référencé 54H0545 a été le plus favorable à la formation des cals quelque soit le milieu de culture auquel il est additionné. De plus, la période d’incubation de 20 semaines a été la plus favorable à l’apparition de cals, par rapport aux périodes d’incubation de 12 et 16 semaines. Enfin, le taux de contamination moyen a été de 24,13 %.

Déterminants de l’appartenance dans les coopératives de production caféière du Kivu

2023-12-05T18:15:10+00:00

Les coopératives agricoles de production constituent la forme la plus répandue d’organisations d’agriculteurs dans le monde. Contrairement à d’autres organisations dont la mission est essentiellement non lucrative, ces coopératives poursuivent des missions à la fois économiques et sociales. L’objectif de cette étude était de trouver les déterminants de l’adhésion aux coopératives de production de café dans la région du Kivu en République Démocratique du Congo (RDC). Une enquête a été menée auprès de 641 caféiculteurs appartenant à des coopératives de production de café. Un questionnaire quantitatif a été utilisé pour la collecte des données. Les résultats indiquent que l’étendue du champ du caféiculteur et la durée du mandat des cadres supérieurs sont généralement les principaux facteurs de démotivation alors que le montant d’adhésion et la quantité de récolte annuellement fournie sont des variables motivationnelles dans la décision d’appartenir à une coopérative de production de café dans le Kivu, en RDC.