African Crop Science Journal

Quantitative trait loci for yield and yield-associated traits in chickpea under drought stress

A.J. Kosgei — Wed, 07 Aug 2024 00:00:00 +0000

Crop yield is a complex phenomenon, controlled by several genes, each contributing to the overall phenotypic expression; which is affected by environment and genotype x environment interactions. Identifying and mapping quantitative trait loci (QTLs), make tracing these traits during breeding possible and easy. The objective of this study was to identify QTLs associated with chickpea (Cicer arietinum L.) grain yield and its associated traits, under drought stress. The experiment was conducted using 188 F3:5 genotypes from ICCV 05107 x ICCV 94954 crosses. Genotypic data were from 49 polymorphic simple sequence repeat (SSR) markers; while phenotypic data were obtained from a field evaluation designed in a 19 x 10 alpha lattice. The study was replicated thrice on three sites, namely at Koibatek Agricultural Training Centre, Muserech; and at the Kenya Agricultural Research and Livestock Organisation, Marigat. Eight QTLs were mapped on a linkage map spanning a total length of 335.04 cM, with varying phenotypic variation expression (PVE%). These QTLs include, one each for days to maturity, 100-seed weight, and two each for above-ground biomass, harvest index, and grain yield. Five major QTLs having PVE ranging from 10.37 to 32.39%, were identified for days to maturity, 100-seed weight above-ground biomass, harvest index (HI), and grain yield. Four of the eight QTLs were mapped on linkage group 4 (LG4); days to maturity, 2 for above-ground biomass, and grain yield. The QTLs mapped are useful in genomic-assisted breeding for chickpea yield improvement. However, there is a need for marker saturation on LGs and specific genes identified for effective marker-assisted breeding.

Efficacy of neem oil for control of stored cowpea seed beetle

C. Gyabeng, S.O. Okyere, V.Y. Eziah, K.O. Fening — Wed, 07 Aug 2024 00:00:00 +0000

Cowpea beetle, Callosobruchus maculatus, is a major pest of stored cowpea. Farmers use mostly synthetic insecticides to control the pest in store, although biopesticides such as neem oil have been proven to be a sustainable alternative. The objective of this study was to determine the effective and feasible rates to enhance cost-effectiveness of neem oil in the management of C. maculatus in stored cowpea grains. A laboratory experiment was conducted, in which sterilised healthy cowpea grains (50 g each) were treated with neem oil at 0, 0.5, 0.75, 1 ml and 0.05 g ACTELLIC Gold Dust® (16 g kg^-1 Pirimiphos methyl + 3.6 g kg^-1 Thiamethoxam). The experiment was laid out in a completely randomised design, with four replications. Results revealed that adult female C. maculatus laid eggs on all the treated cowpea grains, except those treated with 1.0 ml of neem oil. However, no adult emergence and damaged grains were recorded from grains treated with 0.50, 0.75 and 1.0 ml of neem oil. This study has shown that cowpea grains treated with 0.50, 0.75 and 1.0 ml of neem oil outperformed those treated with insecticide actellic dust. Among the rates of neem oil assessed, there was no significant difference between their effect on the management of C. maculatus. Thus, 0.50 ml of neem oil per 50 g of cowpea grains is the most cost-effective rate for the management of C. maculatus in stored cowpea grains.

Antifungal activity of botanicals on causal agents of tomato fungal diseases

K.E.P. Assiri, K. F. Yao , H.A. Diallo — Wed, 07 Aug 2024 00:00:00 +0000

Tomatoes (Lycopersicum esculentum) diseases are among the most constraining factors of tomato production in Côte d’Ivoire. The objective of this study was to evaluate the antifungal activity of Carica papaya and Hydrocotyle bonariensis leaf aqueous extracts, for preventive efficacy against tomatoes diseases agents Alternaria sp., Fusarium sp1 and Fusarium sp2. A greenhouse study was conducted using three different concentrations of leaf extracts (12.5, 25 and 37.5 mg ml-1) obtained by diluting 25, 50 and 75%, respectively, of the crude extract (50 mg ml-1) on the three tomato pathogenic fungi. The concentrations of each of the two extracts with the best fungistatic activities on fungal isolates were selected for in vivo tests. All aqueous extracts inhibited fungal mycelial growth by more than 70%, at the highest concentration (37.5 mg ml^-1); compared to the other two concentrations. At 37.5 mg ml-1, the extracts reduced the severity of fungal diseases on tomato plants compared to the control. Hydrocotyle bonariensis was more effective. A more refined formulation of these extracts could increase their effectiveness and serve for sustainable control of tomato fungal diseases.

Seedball technology overcomes effect of small seed-size and low soil fertility on early pearl millet seedling performance

C.I. Nwankwo , L. Herrmann — Wed, 07 Aug 2024 00:00:00 +0000

In the African Sahel region, pearl millet (Pennisetum glaucum (L). R. Brown) is mostly produced in low-nutrient soils. Available evidence shows that low soil fertility and small seed size significantly reduce seedling establishment and in turn, cause low grain yield. Seedball technology, which refers to a gravimetric mixture of loam soil, seeds, water and additives that improve plant performance, could overcome this effect in the field. The objective of this study was to optimise the influence of seedball on pearl millet (Pennisetum glaucum (L). R. Brown) seedling establishment in the African Sahel region. Conventionally sown and seedball-derived pearl millet seedlings, of a local and improved varieties, were grown for 29 days, from small and large seed sizes, in low- and medium-nutrient soils, in a greenhouse. Results showed that under low-nutrient conditions, and with small seed sizes, P. glaucum produced generally inferior biomas compared to normal nutrient conditions and large seed sizes. On the other hand, seedball technology significantly enhanced (P<0.05) seedling vigour, leaf number, plant height, dry matter accumulation, root length and fine root development; and nutrient uptake, irrespective of soil nutrient level and seed size in the two varieties used in this study. These enhancement effects were more obvious in the local variety compared to its improved counterpart.

Influence of socioeconomic, product and service quality attributes on certified sweetpotato seed use in Uganda

C. Musoke, F.B. Kyazze, P. Kibwika, S. Kyamanywa, S.B. Mukasa — Wed, 07 Aug 2024 00:00:00 +0000

The sweetpotato (Ipomoea batatas (L) Lam) seed system in Uganda is transiting from an informal to a formal setting, by integrating the use of certified sweetpotato seed (CSS) in the production system. Use of CSS enhances productivity by controlling the spread of the sweetpotato virus disease (SPVD) and seed degeneration. However, owing to the limited understanding of product and service quality attributes by farmers, the sustained use of CSS has remained dismal. The objective of this study was to investigate the contribution of farmer socioeconomic characteristics; product and service quality attributes to sustained use of CSS in Uganda. A total of 289 sweetpotato farmers from Central (Mpigi district) and Northern (Omoro district) Uganda, representing low and high SPVD prevalence zones, respectively, were interviewed to obtain information on product attributes (acceptability, accessibility, affordability and awareness) and service attributes (reliability, tangibility, assurance, responsiveness and empathy). Data were subjected to a Double Hurdle analysis. Results revealed that users of CSS scored more for product and service quality attributes, than their non-user counterparts. There was a highly positive correlation between use of CSS and education level in central; but a modestly positive in northern Uganda. Reliability (b = 0.289, 12.612) positively drove the use and extent of use of CSS; while for tangibility (b = -0.302, -11.742), the converse was true. Also, acceptability (b = 0.469, 22.048) increased the use and extent of use of CSS; yet accessibility increased only the use in both locations (b = 0.268). Thus, efforts to scale-out CSS use in the study areas should focus more on affordability, awareness, assurance and empathy based on location; putting into consideration education level and group membership differences.

Optimal sample size for DRIS model parameterisation to diagnosis nutrients status in fruit crops

C.E. Agbangba, A. Aubin , E.L. Sossa — Wed, 07 Aug 2024 00:00:00 +0000

Diagnosis and Recommendation Integrated System (DRIS) is an approach to nutrient diagnosis of crops, holistically through the relationship between nutrient balance of plants and soil. The objective of this study was to investigate the influence of sample size in DRIS model parameterisation, to diagnose nutrients status in fruit crops. Published data were resampled to obtain different sample sizes, ranging from 40 to 1000, with steps of 30. For each sample size, 1000 replications were generated to determine the mean value of the desired parameter (nutrient indices and Nutrient Balance Index). All nutrient indices decreased rapidly as sample size increased from 40 to 200. For each nutrient considered, indices varied slightly from 200 to 1000. This study has revealed that the size of sample used to establish DRIS norms, determines the accuracy of nutrient diagnoses in pineapple (Ananas comosus (L.) Merr.). The optimal data bank for nutrient diagnosis in the crop (pineapple) used in this study is 200.