Blanching and drying period affect moisture loss and vitamin C content in Ziziphus mauritiana (Lamk.)

Wider utilization of Ziziphus mauritania (Lamk) Ber fruits in sub-Saharan Africa is hindered by the rapid deterioration of the fresh fruits and darkening of sun-dried fruits. This study was undertaken to determine the effect of pre-drying treatment, drying method and the subsequent duration of storage on the quality attributes of Z. mauritiana fruits harvested from the Zambezi Valley. The vitamin C content was high at the beginning of the drying period and progressively decreased as the drying increased, and was lowest at three weeks for all drying methods. Effect of drying method was not significant (P > 0.05). The purity (chroma) and lightness (value) of fruit colour decreased (P < 0.001) with increasing drying duration irrespective of the drying method. Blanching fruits before drying significantly (P< 0.001) decreased the colour chroma of the fruits (6.4) in comparison with non-blanched fruits (6.6). Further work to determine the causes of darkening in drying Z. mauritiana fruits and sensory evaluations to determine the level of darkening that is acceptable to consumers is warranted

Effect of Two Formulations of Sufentrazone on Weed Control in Tobacco (Nicotiana Tabacum L)

Field studies were done to compare the weed control efficacy of a wettable granular formulation (Authority 75 WG) and a suspension concentrate formulation (Authority 48 SC) of the herbicide sulfentrazone. A 6 x 2 factorial experiment was laid out in a split plot design to evaluate the effect of the two herbicides on the weed control efficacy in tobacco. The first factor was herbicide which had 6 levels and the second factor was weeding which had 2 levels. One rate of the wettable granular formulation at 0.225 kg/ha, four different rates of the suspension concentrate formulation at 0.165, 185, 0.205 and 0.225 kg a.i. /ha and the untreated control were tested. These were split into two weeding levels (weedy and weed free). The weed free plots were weeded every other week for 12 weeks beginning two weeks after transplanting tobacco. The treatments were combined to give 6 treatments for each main plot. These were replicated four times. This work reported efficacy data from the weedy plots. Weed counts were measured at 4 and 8 weeks after transplanting (WAP) and weed dry-mass at 8WAP. Results show that both formulations at all tested rates poorly controlled broadleaf and grass weeds while nutsedge control was excellent. This study showed that the rates used were too low to effectively control grasses and broadleaved weeds while they were adequate for control of nutsedge. We therefore suggest that this material fills an important niche as a nutsedge material with post emergent nutsedge control. Further work should look at herbicide mixtures in order to improve grass and broadleaf control

Cleaning cycle optimisation in non-tracking ground mounted solar PV systems using Particle Swarm Optimisation

The effect of installation azimuth angle in the optimization of the cleaning cycle of a solar photovoltaic plant was experimentally investigated in this study. The optimum cleaning cycle was determined using Particle Swarm Optimization algorithm cognizance of the fact that different orientations have different soiling rates. Soiling rates on three different azimuth configurations were experimentally investigated and an exponential soiling loss model was developed for each configuration for use in the optimization problem. Azimuth angle differences of ±12.5% were found to have a significant influence on soiling of as much as 28.29% for the selected location. The North of North West configuration was found to be optimal as opposed to the generally accepted North configuration for maximum energy generation at a minimum cost of energy. This configuration generated 0.87% more energy at unit energy cost of $0.093 compared to the North configuration which had a minimum cost of$0.113. The optimized cleaning cycles were 35 days for the optimal configuration while the North configuration had an optimized cleaning cycle of 28 days. A 17.7% difference in the cost of energy was recorded due the influence of soiling. The study revealed that for minimizing the unit energy cost, it is necessary to take into effect the influence of soiling

The Effect of Two Formulations of Sulfentrazone on Soil and Leaf Residues and Phytotoxicity in Tobacco (Nicotiana Tabacum L.)

Field studies were done to compare a wettable granular formulation (Authority 75 WG) and a suspension concentrate formulation (Authority 48 SC) of the herbicide sulfentrazone. A 6 x 2 factorial experiment was laid out in a split plot design to evaluate the effect of herbicide levels on phytotoxicity and residues in both leaves and the soil. One rate of the wettable granular formulation (0.225 kg/ha), four different rates of the suspension concentrate formulation (0.165 kg/ha, 0.205 kg/ha, 0.185 kg/ha, 0.225 kg/ha) and the control (0.00 kg/ha) were tested. Tobacco phytotoxicity at 27 days after transplanting (DAT) and soil residues at 12 WAT was measured. There was significantly higher (P<0.05) phytotoxicity in all treatments where herbicides were applied compared to the control. The WG formulation showed significantly higher phytotoxicity than the SC formulation. Residues in both the soil and leaves were significantly higher in the herbicide applied plots as compared to the control for both formulations. The SC formulation of sulfentrazone at a rate of 0.225 kg/ha was significantly less phytotoxic than the same rate of the WG formulation at 27 DAT. The SC formulation of sulfentrazone can replace the WG formulation for broad spectrum weed control in tobacco in Zimbabwe at a recommended rate of 0.225 kg/ha

Ripening stage and drying method affecting colour and quality attributes of Ziziphus mauritiana fruits in Zimbabwe

Ziziphus mauritiana Lamk. (Ber) fruit is harvested at different stages of ripening in the Zambezi valley of Zimbabwe. We hypothesize that the organoleptic quality attributes of fruits depend on post-harvest drying method and ripening stage at harvest. This study was carried out to evaluate the effect of different stages of ripening on the quality of Z. mauritiana fruits during drying. The fruits were graded into green, yellowish-brown and brown categories and these formed the treatments. Some of these fruits were blanched before drying for 1, 2 and 3 weeks under the solar dryer and the open sun drying methods. The green fruits lost significantly (P&lt;0.001) more weight during drying than the yellowishbrown and brown fruits regardless of the drying methods. The development of browning was more on the brown fruits than the green and yellowish-brown fruits

Groundnut yields response and economic benefits of fungicide and phosphorus application in farmer-managed trials in northern Ghana

Citation: Naab, J. B., S. S. Seini, K. O. Gyasi, G. Y. Mahama, P. V. V. Prasad, K. J. Boote, and J. W. Jones. “GROUNDNUT YIELD RESPONSE AND ECONOMIC BENEFITS OF FUNGICIDE AND PHOSPHORUS APPLICATION IN FARMER-MANAGED TRIALS IN NORTHERN GHANA.” Experimental Agriculture 45, no. 4 (October 2009): 385–99. https://doi.org/10.1017/S0014479709990081.Prior on-station research showed that sowing dates, sowing density and applications of fungicide and phosphorus (P) increased groundnut (Arachis hypogaea) pod yield by 60–80%. Farmer-managed trials were conducted in the Wa district of the Upper West Region of Ghana from 2004 to 2007 to test the yield response to sowing density, fungicide and P and to assess economic returns of these technologies to farmers. Treatments included: an early maturing groundnut cultivar, Chinese, sown at farmers’ density (5–8 plant m−2) without fungicide and without P application (T1, control), with fungicide sprays alone (T2), or with fungicide and P application (T3), cultivar Chinese sown at recommended (higher) density (20 plant m−2) with fungicide and P application (T4), and a full season cultivar, Manipinter, with fungicide and P application (T5). Soil fertility, sowing density, days from sowing to first weeding, incidence and severity of leaf-spot disease and plant population at final harvest were recorded. Relative to farmers’ practice, pod yield of cultivar Chinese was significantly increased by 80% with fungicide sprays alone, 108% with fungicide and P application, and 113% with fungicide and P application at higher sowing density. Cultivar Manipinter treated with fungicide and P gave 107% increase in pod yield relative to farmers’ practice. Correlation and stepwise regression analyses suggested that major determinants of groundnut pod yield in farmers’ fields were plant density, leaf-spot disease and P availability. The increase in yield with fungicide and P application translated into a 4–5-fold increase in gross margin for farmers in the region. Returns to labour and labour productivity were doubled with combined use of fungicide and P fertilizer

Influence of fungicide and sowing density on the growth and yield of two groundnut cultivars

Citation: Naab, J. B., K. J. Boote, P. V. V. Prasad, S. S. Seini, and J. W. Jones. “Influence of Fungicide and Sowing Density on the Growth and Yield of Two Groundnut Cultivars.” The Journal of Agricultural Science 147, no. 2 (April 2009): 179–91. https://doi.org/10.1017/S0021859608008290.Groundnut or peanut (Arachis hypogaea L.) is a valuable food and forage crop in West Africa. It is important to determine yield-limiting factors and to develop suitable management practices to improve groundnut productivity. The objective of the present research was to determine the influence of fungicide application at different sowing densities on growth, biomass and yield of early and late maturing groundnut under rainfed conditions. Two groundnut cultivars (Chinese, 90 days duration and Manipinter, 120 days duration) were grown at low (8 plants/m2), medium (12 plants/m2) and high density (20 plants/m2), with and without fungicide application, for two growing seasons (2004 and 2005). Data on leaf area index (LAI), light interception (LI) and total biomass were measured at different stages of crop development. Haulm (stem and leaf), pod and seed yields were measured at maturity. Fungicide application increased LAI, LI and total biomass of both cultivars from 65 days after sowing (DAS) until maturity. Fungicide application significantly increased pod and seed yields by 95 and 103%, respectively, on average. In both years, the long duration cultivar Manipinter had significantly greater LAI, LI and total biomass at later stages of crop development when compared with the short-duration cultivar Chinese. The growth and yield of both cultivars were significantly less at the lowest population density when compared with medium or high population densities. There was no significant difference between medium and high population densities in haulm, pod and seed yield at maturity. It is concluded that sowing a long-duration cultivar at a density of 12 plants/m2 with fungicide application significantly improved groundnut yields under rainfed conditions in Ghana