African Journal of Agriculture

zAfrican Journal of Agriculture ISSN 2375-1134 Vol. 3 (1), pp. 125-134, January, 2016.  © International Scholars Journals

Full Length Research Paper

Morpho-physiological parameters used in selecting drought tolerant cowpea varieties using drought index

Freddy Dramani Pele¹*, Asamoah Yeboah², Marcel Shatta Buari¹ and E. J. Kofi²

¹Institut National de la Recherche Agronomique du Niger (INRAN), Niamey/Niger. ²Department of Crop and Soil Sciences/Faculty of Agriculture/KNUST/Kumasi/Ghana.

E-mail: [email protected]

Accepted 18 December, 2015

Abstract

Drought stress represents one of the most important abiotic constraints limiting cowpea production in the arid and semi-arid zones of Africa. Since drought susceptibility index (S) represents drought tolerance at whole plant level regardless of drought tolerance mechanism in operation, a potted experiment was conducted in a plant house (August to October 2011) to identify morpho-physiological parameters and develop drought susceptibility index for selecting drought tolerant cowpea varieties. These parameters included relative water content (RWC), plant height (PHT), number of leaves per plant (NL), stem diameter (SD) and root dry mass (RDM). A 2×6 factorial arranged in completely randomized design with three replications was used. The results showed highly significant effects among the cowpea genotypes, as regards to the water regime treatments and their interaction for all the morpho-physiological parameters used in this study (RWC, PHT, NL, SD and RDM). Significant positive relationship was found between NL and RDM with r = 0.97, p<0.001. With relatively better performance under water-stressed condition, as indicated by the drought susceptibility index, variety Dan illa was the best genotype recommended to be used as source for drought tolerance in a cowpea breeding programme. 

Key words: Drought tolerance, morpho-physiological parameters, drought intensity, drought susceptibility index

African Journal of Agriculture ISSN 2375-1134 Vol. 2 (8), pp. 116-124, August, 2015. © International Scholars Journals

Full Length Research Paper

The efficacy of Eucalyptus grandis and Tagetes minuta ground leaf powders as grain protectants against Sitophilus zeamais in stored maize

Robert Mwaruwari Morgan

Faculty of Agriculture and Natural Resources, University of Zimbabwe, Harare, Zimbabwe.

E-mail: [email protected]

Accepted 25 July, 2015

Abstract 

Use of plant compounds in grain protection has shown great potential as an alternative to synthetic insecticides in Sub-Saharan Africa. This study investigated the efficacy of Eucalyptus grandis and Tagetes minuta ground leaf powders as grain protectants against Sitophilus zeamais in stored maize. Effect of leaf powders were evaluated on percent germination, percent weight loss of grain, insect infestation, grain colour and odour over 192 days (≈six months) duration. Leaf powders (2.5 and 5 g/kg), synthetic pesticide (Actellic Chirindamatura dust (0.5 g/kg)) and an untreated control were used as treatments. All plant powders significantly minimized grain damage and infestation 96 days post treatment (≈three months) and had no effect on percent germination of maize grains when compared to controls. However, variable responses dependent upon botanical plant cultivars and rate of application were observed from three to six months after application. Grain colour and odour were not affected by plant powders over six months of storage. E. grandis and T. minuta significantly reduce grain damage and insect infestation with no adverse effects on seed germination, colour and odour hence can be used as sustainable alternatives to synthetic insecticides in maize storage especially by smallholder farmers.

Key words: Sitophilus zeamais, efficacy, Eucalyptus grandis, Tagetes minuta, maize, organoleptic.

African Journal of Agriculture ISSN 2375-1134 Vol. 2 (7), pp. 107-115, July, 2015. © International Scholars Journals

Full Length Research Paper

Fundamental genetic patterns controlling disease resistance and identification of suitable parental lines in varietal tolerance development of cotton yield

 Robert Mwaruwari Morgan

Faculty of Agriculture and Natural Resources, University of Zimbabwe, Harare, Zimbabwe.

E-mail: [email protected]

Accepted 30 June, 2015

Abstract 

Verticillium wilt disease causes significant losses to cotton yield and varietal development for resistance is critical in combating this threat. A study was carried out to determine the underlying genetic pattern controlling disease resistance and identify suitable parental lines to use in varietal tolerance development. Five cotton varieties were crossed in a half diallel mating system to produce ten crosses and five selfed parental lines which were screened against Verticillium wilt by artificial inoculation. There were significant variations on the severity scores, vascular brown index scores, morphological and agronomical traits under Verticillium wilt pressure. The Verticillium wilt severity scores ranged from 1.22 to 3.07 and Vascular Brown Index scores from 0.78 to 2.77. The mean squares of general combining ability (GCA) for the various characteristics of the parents were significant and also for the specific combining ability (SCA) of the vascular brown index score which was 0.27 was also significant. Three parental lines were identified as breeding material with good GCA, morphological and agronomical performance and these were CRI-MS-1, SZ9314 and BC853. This study implies that varietal tolerance can be developed by incorporating genotypes with resistance genes in breeding programmes. Future work should focus on developing resistant varieties suitable for production in Verticillium wilt prone areas.

Key words: Verticillium wilt, general combining ability, specific combing ability, cotton.

African Journal of Agriculture ISSN 2375-1134 Vol. 2 (6), pp. 099-106, June, 2015. © International Scholars Journals

Full Length Research Paper

Agronomic evaluation and germplasm characterization of Tannia (Xanthosoma sagittifolium (L.) variety development in Ethiopia

Mengistu F. Goirgis

Department of Horticulture, Faculty of Agriculture, Arba Minch University, Arba Minch, Ethiopia.

E-mail: [email protected]

Accepted 26 May, 2015

Abstract 

Tannia is one of the most important root and tuber crops for food, feed and industrial applications worldwide. However, the progress to variety development in Ethiopia is so slow due to lack of adequate germplasm characterization and agronomic evaluation for yield and quality. Therefore, a total of 64 tannia genotypes were studied to determine the extent of genetic variability among genotypes at Jimma agriculture research center during 2013/2014 cropping season. 62 of the genotypes were collected from south, south western and western parts of Ethiopia and the rest two were introduced from Cuba, laid out in 8 × 8 simple lattice design. Analysis of variance revealed significant (P 0.01) differences for most of the characters, indicating the existence of variability among the studied genotypes. High phenotypic coefficient of variation (PCV) along with moderate to high genotypic coefficient of variation (GCV) as well as high heritability coupled with high genetic advance as percent of the mean were obtained for number of suckers per plant, number of cormel per plant, total yield per plant, corm and cormel fresh weight per plant. This indicates that there is an opportunity and potential for further utilization of its genetic improvement through selection and hybridization. However, the presence of morphological variation between genotypes is not a guarantee for high genetic variation. Hence, there is a need to confirm genotype-environment interactions and use biotechnological approaches as a complementary to this study.

Key words: Genetic advance, genetic variability, genotypic coefficient of variation, heritability.

African Journal of Agriculture ISSN 2375-1134 Vol. 2 (5), pp. 092-098, May, 2015. © International Scholars Journals

Full Length Research Paper

Evaluation of the characteristics of Valiosa cultivar soybean grain dried under different air conditions

Montenegro Neymar Benicio

Faculdade de Ciências Agronômicas, Universidade Norte do Parana, Londrina, Brazil.

E-mail: [email protected]

Accepted 23 April, 2015

Abstract 

The aims of this work were to adjust different mathematical models to experimental data describing the drying of the Valiosa cultivar soybean grain, to determine and to evaluate the effective diffusion coefficient and to obtain the activation energy and the thermodynamic properties of the drying process under different air conditions. The Valiosa cultivar soybean grains, with an initial moisture content on a dry basis of 0.56 (d.b., decimal), were dried in an oven with forced air ventilation at five different temperatures (40, 55, 70, 85 and 100°C) until reaching a moisture content of 0.133 ± 0.019 (d.b.). Of the models analyzed, Page’s model was selected to best represent the drying phenomenon. The effective diffusion coefficient of soybeans increased with the air temperature and was described by the Arrhenius equation; an activation energy of 22.77 kJ mol^-1 was reported for liquid diffusion in the drying of the soybeans. The enthalpy and entropy decreased with increasing temperature, while the Gibbs free energy increased with increasing drying temperature.

Key words: Glycine max, liquid diffusivity, enthalpy, entropy, Gibbs free energy.

African Journal of Agriculture ISSN 2375-1134 Vol. 2 (4), pp. 085-091, April, 2015. © International Scholars Journals

Full Length Research Paper

A possible cultivation system towards genetic improvement of Plectranthus edulis (Vatke) Agnew from shoot tip and nodal explants

Mulatu Gebre Makonnen

Department of Biology, Faculty of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia.

E-mail: [email protected]

Accepted 8 March, 2015

Abstract 

Plectranthus edulis Vatke belongs to the family of Lamiaceae, which occurs both as a wild and cultivated species. The major constraint in the cultivation of P. edulis is its low productivity due to shortage of planting materials and incidence of pests and diseases. In this study, an efficient protocol was established for the micropropagation of P. edulis germplasm using shoot tip and nodal explants. Explants were sterilized using different concentrations of Sodium hypochlorite (NaOCl) for different times of exposure. MS medium supplemented with different types and concentrations of auxin and cytokinin were used for culture initiation, shoot multiplication and root induction. NaOCl at a concentration of 2% and exposure time of 5 min gave 74.50±0.5% of clean culture for nodal and 69.83±0.76 from shoot tip. Six-Benzylaminopurine at 1.5 µM was found to be an optimum concentration for shoot induction, yielding 91.67±0.58% for nodal and 85.57±0.51% for shoot tip explants 3 weeks after culture. The combination of 2.0 µM BAP with 1.0 µM IAA was found to be the optimum concentration yielding 10.28±0.06 and 6.12±0.01 shoots per explants for nodal and shoot tip, respectively for shoot multiplication. Half strength MS medium with 2.0 µM IBA and 1.0 µM NAA gave the highest rooting percentage (97.00±0.28) with optimum root number (33) and length (3 cm). Up on acclimatization and transplanting, 83% survival efficiency was observed on soil mix ratio of 2:1:1 decomposed coffee husk, forest soil and sand, respectively. There were no observable variations with respect to morphology and growth characteristics to the greenhouse raised parent plants. The results obtained in this study permit the development of mass propagation protocol that could enable large scale commercial production of this highly demanded cultivar true-to type and provide a possible system towards genetic improvement of the crop.

Key words: Explants, micropropagation, nodal culture, microshoots, plant growth regulators, plantlet