The effect of plant growth regulators on callus initiation in wormwood (Artemisia annua L.)

Studies were carried out in the Biotechnology laboratory of Plant Science Department of Ahmadu Bello University Zaria, Nigeria to study the effect of some plant growth regulators on the in vitro initiation of callus using the leaves of Chiyong variety of Artemisia annua. The explants were sterilized and incubated on Murashige and Skoog basal media augmented with varying concentrations ranging from 0.5 to 3.0 μm/l of Giberellic acid (GA3), Benzyle amino purine (BAP), Naphthyle acetic acid (NAA),2,4-Dichlrophynoxyacetic acid (2,4-D), Indole butyricacid (IBA) and Kinetin (Kin). The experiment was arranged in a completely randomized design with 2 replicates. Low BAP concentration of 0.5 μm/l and a high concentration of NAA of 3.0 μm/l as well as equal concentration of BAP of 1.0 μm/l and IBA of 1.0 μm/l had the least days (7days) to regeneration. For regeneration percent, equal low concentrations of BAP of 0.5 μm/l and NAA of 0.5 μm/l had the highest performance of 94%. However, no significant difference was observed between treatments with respect to vigor. Equal low concentrations of BAP (0.5 μm/l) and (0.5 μm/l) NAA and BAP(1.0 μm/l) combined with IBA(1.5 μm/l) had the highest height. Results of Analysis of Variance (ANOVA) indicated significant difference among the treatments compared with the control (P<0.05). Therefore, combined BAP and NAA treatment is an efficient protocol for callus initiation and proliferation. A combination of GA3 and BAP is suitable for shoot initiation from callus using cultures of A. annua.Keywords: Artemisia annua, in vitro, Nodal cuttings, growth regulator

Heritabiliy Studies In Some Sweet Sorghum (Sorghum Bicolor. L. Moench) Genotypes

Studies were carried out to estimate the extent of heritability in some cultivated genotypes of sweet sorghum (Sorghum bicolor L. Moench). Thirty genotypes were used for the evaluation. The phenotypic coefficient of variation (PCV) was greater than the genotypic coefficient of variation (GCV) for most traits studied. Days to 50% flowering (DTF) had low PCV and GCV. Head weight had low GCV but higher PCV. 1000 grain weight was also low for PCV and GCV. Moderate GCV was observed within the range of 11.7 (stem thickness) to 19.8 (number of nodes). High GCV was observed within the range of 22.3 (panicle length) to 31.5 (sugar content). Moderate PCV ranged from 13.3 (stem thickness) to 16.6 (number of nodes) and PCV ranged from 20.0 (number of nodes) to 43.3 (head weight). But the GCV was near to PCV for traits like DTF, plant height, number of nodes, number of leaves, grain yield and sugar content, indicating a highly significant effect of genotype on phenotypic expression for these traits with very little effect of environment. The genotypes studied showed high heritability for eight (8) traits out of the 10 traits studied in the range of 69.4 (plant height) to 97.3 (number of nodes). Moderate heritability of 55.9 was observed for 1000 grain weight and low heritability of 1.5 for head weight. Keywords: heritability, GCV, PCV, genotypes

Distribution and diversity of alternate hosts of Maruca vitrata Fabricius in three West African countries

The evolution of resistance to the Bacillus thuringiensis (Bt) toxins by insect pests is a major threat to Bt technology. However, the rate of resistance can be slowed with appropriate integrated insect resistance management (IRM) strategies. Surveys were conducted to identify alternate host species for Maruca vitrata (commonly called the legume pod borer or Maruca) that could serve as refuges for Pod-Borer Resistant (PBR) cowpea in three West African countries (Ghana, Nigeria, and Burkina Faso). Survey sites included 25 in northern Ghana, 44 in northern Nigeria, and 52 in north-central and southwestern Burkina Faso. Alternate hosts of Maruca identified from plant species belonging to the Fabaceae family that showed signs of Maruca damage on cowpea tissues were collected and dissected. Larvae that were found during these dissections were reared to adult moths in the laboratory then identified to species. The alternate host plants including species of Crotolaria, Sesbania, Tephrosia, and Vigna were the most frequently encountered among sites and locations. Flowering and podding of these plants overlapped with flowering and podding of the nearby (~200 m) cowpea crop. Abundance of these wild hosts and overlapping flowering patterns with the cowpea crop in most locations have the potential to sustain ample numbers of Bt susceptible Maruca that will mate with possible resistant Maruca and deter resistance development. Further quantitative studies, however, are required from each location to determine if actual Maruca production from alternate hosts is sufficient for a PBR IRM strategy. If verified, this approach would be compatible with the high dose/refuge IRM strategy that includes alternate hosts and non-Bt crops as refuges

Efficacy of a cry1Ab Gene for Control of Maruca vitrata (Lepidoptera: Crambidae) in Cowpea (Fabales: Fabaceae)

Cowpea [Vigna unguiculata (L) Walp.] is an important staple legume in the diet of many households in sub-Saharan Africa. Its production, however, is negatively impacted by many insect pests including bean pod borer, Maruca vitrata F., which can cause 20–80% yield loss. Several genetically engineered cowpea events that contain a cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against M. vitrata were evaluated in Nigeria, Burkina Faso, and Ghana (West Africa), where cowpea is commonly grown. As part of the regulatory safety package, these efficacy data were developed and evaluated by in-country scientists. The Bt-cowpea lines were planted in confined field trials under Insect-proof netting and artificially infested with up to 500 M. vitrata larvae per plant during bud formation and flowering periods. Bt-cowpea lines provided nearly complete pod and seed protection and in most cases resulted in significantly increased seed yield over non-Bt control lines. An integrated pest management strategy that includes use of Bt-cowpea augmented with minimal insecticide treatment for protection against other insects is recommended to control pod borer to enhance cowpea production. The insect resistance management plan is based on the high-dose refuge strategy where non-Btcowpea and natural refuges are expected to provide M. vitrata susceptible to Cry1Ab protein. In addition, there will be a limited release of this product until a two-toxin cowpea pyramid is released. Other than South African genetically engineered crops, Bt-cowpea is the first genetically engineered food crop developed by the public sector and approved for release in sub-Saharan Africa

Inheritance of shortday induced dwarfing in photosensitive cowpeas

Cowpea [ Vigna unguiculata (L.) Walp.] is an important source of food and fodder in the dry savanna of West Africa. Traditional cowpea varieties are photosensitive (PS), growing profusely when planted in long days and they flower when days become shorter. However, we have observed that all PS cowpea varieties exhibit dwarf characteristics when planted during short-days. This study was undertaken to confirm this observation and to elucidate the inheritance of shortday induced dwarfing in PS cowpea. Two PS and two Photoinsensitive (PI) cowpea varieties were evaluated at IITA Kano Station, Nigeria (12003'N latitude and 8032'E longitude) at 4 planting dates. As expected, PS varieties flowered earlier when planted during short days (13 h., May and July plantings). However, they became extremely dwarf during short days due to lack of internode elongation resulting in a rosette appearance. The mean plant heights of PS varieties were 20.5 cm, 142 cm, 89.0 cm and 15.0 cm, when planted in February, May, July and October, respectively. The corresponding plant heights of the PI varieties were 39.0 cm, 31.5 cm, 26.0 cm and 24.5 cm. The parental, F1, F2 and backcross populations derived from a PI variety IT87D-941-1 and a PS variety, Kanannado were evaluated in short day conditions and selected F3 progenies tested in long-day conditions. The genetic segregation revealed that short-day-induced dwarfing of PS is controlled by a single recessive gene pair which is designated as 'psps (photosensitive). The complete correspondence between dwarfing under short-day conditions and PS for flowering, indicates that both phenomena are manifestation of the same PS gene pair. RESUME Le niebe [Vigna unguiculata (L.) Walp.] est une importante source de nutriture et de fourage dans la savanne seche de l' Afrique de l'Ouest. Les varietes traditionnelles de vigna sont photosensibles, poussant exuberamment quand elles sont plantees en jours longs et elles flourissent quand les jours reccounissent. Cependant, nous avons observe que toutes les varietes de niebe manifesterent des caracteristiques de nanisme quand elles sont plantees en jours courts. Cette etude fut entreprise pour confirmer cette observation et pour elucider l'heritabilite du nanisme induit par les jour courts. Chez les varietes de vigna photosensibles. Deux varietes photosensibles et deux insensibles a la photoperiod furent evaluees a la Station Kano, IITA, Nigeria a 4 dates de semis comme attendu la varietes photosensibles fleurirent plus tot quand elles furent plantees en jours courts

Inheritance of time to flowering in cowpea (Vigna unguiculata (L.) Walp.)

Time to flowering and maturity is an important adaptive feature in annual crops, including cowpeas (Vigna unguiculata (L.) Walp.). In West and Central Africa, photoperiod is the most important environmental variable affecting time to flowering in cowpea. The inheritance of time from sowing to flowering (f) in cowpeas was studied by crossing a photoperiod-sensitive genotype Kanannnado to a photoperiod-insensitive variety IT97D-941-1. Sufficient seed of F-1, F-2, F-3 and backcross populations were generated. The parental, F-1, F-2, F-3 and the backcross populations were screened for f under long natural days (mean daylength 13.4 h per day) in the field and the parents, F-1, F-2 and backcross populations under short day (10 h per day) conditions. The result of the screening showed that photoperiod in the field was long enough to delay flowering of photoperiod-sensitive genotypes. Photoperiod-sensitivity was found to be partially dominant to insensitivity. Frequency distribution of the trait in the various populations indicated quantitative inheritance. Additive (d) and additive x dominance (j) interactions were the most important gene actions conditioning time to flowering. A narrow sense heritability of 86% was estimated for this trait. This will result in 26 days gain in time to flowering with 5% selection intensity from the F-2 to F-3 generation. At least seven major gene pairs, with an average delay of 6 days each, were estimated to control time to flowering in this cross

Screenhouse Evaluation of Pearl Millet Genotypes for Downy Mildew Incidence

Abstract: Four resistant to downy mildew pearl millet varieties was crossed to four susceptible to downy mildew pearl millet varieties. The hybrids (16) and their parents were evaluated for downy mildew incidence in the screen house. From the study all the resistant parents were found to be susceptible and the susceptible parents maintain their status. Among the hybrids only LCIC9702 X DMR15 was moderately resistant while BDP1 X DMR15, M0P1 X DMR15, LCIC9702 X P1449 and PE05984 X DMR15 were Moderately Susceptible

Assessment of Genetic Variability of Some Quantitative Traits of Cowpea (Vigna unguiculata [L.,] walp) Varieties

The studies on the assessment of genetic variability of some quantitative traits of cowpea (Vigna unguiculata [L.,] WALP) varieties were conducted at the green house of the Institute for Agricultural Research (IAR), Ahmadu Bello University, Zaria, Nigeria. Completely Randomized Design was used. The Seeds of the three cowpea varieties (IT87D 941-1, IT97K 499-35 and Dankurmi) were sown in Plastic pots and are arranged in six replications. Variations of selected quantitative traits were studied in three cowpea varieties (IT87D941 - I, IT97K 499 - 35 and Dankurmi) and their F1 and F2 hybrids. The first two varieties are improved varieties which are tall and photo-insensitive. The latter is a local variety which is short and photo-sensitive. There were improvements in quantitative traits of F1 hybrids derived from crosses involving Dankurmi. Highly significant differences were observed in many traits such as height at maturity, number of pods per plants, length of pods per plants, number of seed per pod and leaf area in the F2 population. Positive correlation coefficient was obtained and this will enhance productivity through selection using the two characters positively correlated. It was concluded that hybrid plants were found to be vigorous and intermediate between the parent varieties with respect to many quantitative traits. The seed set data indicated that cross compatibility was lower in crosses involving Dankurmi, which may be due to low pollen content and the high seed set in IT87K 499-35 suggests high receptivity for pollen. This may be due to high fertility and compatibility. This study recommended that cross combination through the use of hybridization would improve the quality and quantity of quantitative traits which would in turn improve the quality and quantity of cowpea genotypes (varieties)