Evaluation of Bambara groundnut varieties for off-season production in Zimbabwe

Early planting of bambara groundnuts (Vigna subterranea L. Verdc) in the southern Africa enables farmers to fetch premium prices before the markets are flooded with produce from the main summer growing period.However, adaptation of the crop outside the main growing season has not been studied in Zimbabwe. Therefore, this study evaluated 20 varieties at four planting dates covering contrasting temperatures and daylength, at Harare Research Station, during 2000/2001. Planting date was the main plot factor replicated three times and cultivar the subplot. Standard agronomic practices were followed and adequate moisture supplied through supplementary irrigation. Both the planting dates and variety main effects were significant (

EFFICACY OF BOTANICAL EXTRACTS FROM GARLIC AND NEEM ON CONTROLLING POTATO SOFT ROT PATHOGENS

Soft rot of potatoes (Solanum tuberosum L.) caused by Pectobacterium and Dickeya subspecies leads to economic losses in agriculture worldwide including Zimbabwe, where losses range from 20 – 60%. A laboratory experiment was carried out using the potato tuber maceration test to screen the effect of two botanicals extract, neem (Azadirachta indica A. Juss.) leaf and garlic (Allium sativum L.) cloves in controlling soft rot disease caused by bacterial pathogens, namely Pectobacterium carotovorum subspecies carotovorum (Pcc), Pectobacterium atrosepticum (Pa) and Dickeya dadantii (Dd). Preparations of two concentrations [(10 and 25% (w/v)] of the aqueous extracts of garlic and neem plants were used in dip and spray applications. Sterile distilled water was used as a negative control. Three tuber halves were used for each treatment. Five 10 mm filter paper discs (Whatman’s No. 1) pre-soaked in 1 x 106 cfu/mL bacterial cell suspensions of Pcc, Pa and Dd respectively were placed on each tuber half and incubated for 48 h at 25oC. After 48 h the filter paper discs were removed and the rotting zone diameter was measured. The experiment was a 3x2x2x2+1 factorial laid out in a completely randomised design, each treatment replicated three times. The two botanicals significantly inhibited the growth of two bacteria, Pa and Dd but were ineffective against Pcc. Concentration, method of application and their interactions were not significant in inhibiting the bacteria. Neem and garlic extracts can be used to control Pa and Dd infections

Effect of BAP, NAA and GA3, either alone or in combination, on meristem culture and plantlet establishment in sweet potato (cv Brondal)

In Zimbabwe, the average sweet potato yield (6 t/ha) is relatively low when compared to Asian counterparts (17 t/ha). These low crop yields have been blamed on weevil infestations and viral infections which account for 60-90% of sweet potato yield losses in Africa. Meristem tip culture, a Centre for Potato Improvement (CIP) initiated tissue culture technique, has been widely used to eradicate viruses from clonally propagated crops and has been noted to be one of the instrumental techniques that helped China to increase sweet potato yields. In an effort to adopt the meristem tip culture technique for the production of virus-free planting material of a local sweet potato (cv Brondal), a study was conducted to evaluate the effect of Benzylamino purine (BAP), 1-Naphthaleneacetic acid (NAA) and Gibberellic acid (GA3) (either alone or in combination) on cultured Brondal meristems. The different hormonal treatments were assessed on the following parameters: plantlet regenerative capacity, multiple plantlet production, shoot height, average leaf number per shoot and average node number per shoot, ten weeks after meristem culture. All treatments containing a combination of BAP (1 mg-L) and GA3 (at either 5 mg-L, 10 mg-L, or 20 mg-L) had a significantly (p<0.01) higher plantlet regenerative capacity of 33-66% when compared to other treatment combinations. Only treatments, 10 mg-L GA3 + 1 mg-L BAP and 20 mg-L GA3 + 1 mg-L BAP were capable of inducing multiple plantlet formation, producing an average of three plantlets/meristem and two plantlets/meristem respectively. Overall, treatment 10 mg-L GA3 + 1 mg-L BAP gave rise to significantly (p<0.01) taller shoots (20 mm) compared to the rest of the treatments used. For average leaf number per shoot, all GA3 treatments (5 mg-L, 10 mg-L, or 20 mg-L) supplemented with 1 mg-L BAP gave significantly (p<0.01) higher numbers of leaves (six leaves/shoot) than the rest of the treatments. Treatments 10 mg-L GA3 + 1 mg-L BAP and 20 mg-L GA3 + 1 mg-L BAP gave rise to the highest number of nodes per shoot, producing an average of three nodes per shoot. In sharp contrast to treatments containing a combination of BAP and GA3, all treatments containing a combination of BAP and NAA performed poorly in all parameters tested for plant regeneration of Brondal sweet potato variety. In conclusion, the best hormonal treatment for culturing Brondal meristems proved to be 10 mg-L GA3 + 1 mg-L BAP.Keywords: Ipomoea batatas, meristem, regeneration, Benzylamino purine, Gibberellic acid, 1-Naphthaleneacetic aci

Field performance of spider plant (Cleome gynandra l) under different agronomic practices

Field experiments were carried out at Kaguvi Vocational Training Centre located in theMidlands province of Zimbabwe, to determine the effect of planting date and fertilizertypes in enhancing the productivity of spider plant, an indigenous leafy vegetable. Theexperimental design was a split- plot arranged in a randomized complete block design(RCBD) with three blocks. The planting date was the main plot with three levels(15/10/12, 30/01/13 and 15/02/13) and the fertilizer treatments as the subplots withseven levels including a control (no fertilizer applied), 20 t/ha cattle manure, 30 t/hacattle manure, 5 t/ha poultry manure, 10 t/ha poultry manure, 300 kg/ha Compound D +100 kg/ha ammonium nitrate and 300 kg/ha Compound D + 150 kg/ha ammoniumnitrate). Growth parameters, vitamin A and C, crude protein, iron content, fresh and dryyield were significantly (p<0.05) increased by use of organic and inorganic fertilizersacross all planting dates compared to the control where no fertilizers were added. TheOctober 2012 planting date, combined with high rates of organic and inorganicfertilizers had the best response with regards to the variables measured, including theduration of the harvest period which was nine weeks, compared to the January andFebruary planting dates where harvesting was for six weeks. The inorganic fertilizersprovided readily available nutrients for uptake by the plants while the long productionperiod for the October 2012 planting date enabled the organic manures (cattle andpoultry manure) adequate time to release the nutrients for uptake, compared to theJanuary 2013 and February 2013 planting dates. It can be concluded that there is meritin staggering the planting dates while using organic and inorganic fertilizers as thepractice results in an extended harvest period. High rates of both inorganic and organicfertilizers are recommended for the different planting dates as follows; 30 t/ha cattlemanure, 10 t/ha poultry manure, 300 kg/ha Compound D + 100 kg/ha ammoniumnitrate and 300 kg/ha Compound D + 150 kg/ha ammonium nitrate.Key words: Indigenous vegetable, spider plant, planting dates, fertilizers, nutrient

Variability of Grain-filling Traits in Early Maturing CIMMYT Tropical Maize Inbred Lines

Grain-filling rate (GFR), effective grain-filling duration (EGFD) and total grain-filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yeild (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is pre-requisite for improvement in early maturing maize

EFFECT OF BAP, NAA AND GA3, EITHER ALONE OR IN COMBINATION, ON MERISTEM CULTURE AND PLANTLET ESTABLISHMENT IN SWEET POTATO (CV BRONDAL)

ABSTRACT In Zimbabwe, the average sweet potato yield (6 t/ha) is relatively low when compared to Asian counterparts (17 t/ha). These low crop yields have been blamed on weevil infestations and viral infections which account for 60-90% of sweet potato yield losses in Africa. Meristem tip culture, a Centre for Potato Improvement (CIP) initiated tissue culture technique, has been widely used to eradicate viruses from clonally propagated crops and has been noted to be one of the instrumental techniques that helped China to increase sweet potato yields. In an effort to adopt the meristem tip culture technique for the production of virus-free planting material of a local sweet potato (cv Brondal), a study was conducted to evaluate the effect of Benzylamino purine (BAP), 1-Naphthaleneacetic acid (NAA) and Gibberellic acid (GA3) (either alone or in combination) on cultured Brondal meristems. The different hormonal treatments were assessed on the following parameters: plantlet regenerative capacity, multiple plantlet production, shoot height, average leaf number per shoot and average node number per shoot, ten weeks after meristem culture. All treatments containing a combination of BAP (1 mg -L) and GA3 (at either 5 mg -L, 10 mg -L, or 20 mg -L) had a significantly (p<0.01) higher plantlet regenerative capacity of 33-66% when compared to other treatment combinations. Only treatments, 10 mg -L GA3 + 1 mg -L BAP and 20 mg -L GA3 + 1 mg -L BAP were capable of inducing multiple plantlet formation, producing an average of three plantlets/meristem and two plantlets/meristem respectively. Overall, treatment 10 mg -L GA3 + 1 mg -L BAP gave rise to significantly (p<0.01) taller shoots (20 mm) compared to the rest of the treatments used. For average leaf number per shoot, all GA3 treatments (5 mg -L, 10 mg -L, or 20 mg -L) supplemented with 1 mg -L BAP gave significantly (p<0.01) higher numbers of leaves (six leaves/shoot) than the rest of the treatments. Treatments 10 mg -L GA3 + 1 mg -L BAP and 20 mg -L GA3 + 1 mg -L BAP gave rise to the highest number of nodes per shoot, producing an average of three nodes per shoot. In sharp contrast to treatments containing a combination of BAP and GA3, all treatments containing a combination of BAP and NAA performed poorly in all parameters tested for plant regeneration of Brondal sweet potato variety. In conclusion, the best hormonal treatment for culturing Brondal meristems proved to be 10 mg -L GA3 + 1 mg -L BAP