Soil infertility is one of the constraints contributing to poor sorghum production in semi-arid areas across Africa. To increase sorghum production, there is need to address soil fertility issues. Therefore, the objective was to assess the effects of Leucaena/cattle manure combination on grain and stover yields, harvest index and net return of two sorghum varieties (Macia and SV1) under rainwater harvesting techniques. The field experiment was conducted as a randomized complete block design over three cropping seasons in a split-split plot arrangement. Results show significant (P < 0.05) increase in sorghum grain yield with increased applications of Leucaena/cattle manure combination. Macia variety had statistically greater (P < 0.05) grain yield than SV1 variety. Tied contour show considerably higher yield for both varieties across all seasons. Stover yield show significant differences (P < 0.05) as affected by Leucaena/cattle manure and rainwater harvesting techniques. Rainwater harvesting techniques significantly influence (P < 0.05) harvest index, with tied contour and infiltration pits having comparably higher harvest index than standard contour. Application of Leucaena/cattle manure combination show significant increases in harvest index with increased application rates. However, no significant effect was observed at 20 and 30 t ha⁻¹ from SV1 variety across all seasons. Leucaena/cattle manure combination significantly influenced (P < 0.05) sorghum net return across all seasons except at 5 t ha⁻¹ where no significant effect was observed. Macia variety had higher net return than SV1. To increase grain yield and net return, farmers can adopt Macia variety, tied contour and 10 t ha⁻¹ Leucaena/cattle manure combination due to higher incremental yield per tonne.

Striga hermonthica, Striga asiatica and Striga gesneroides are obligate root parasites that cause severe yield losses in cereals and legumes in sub-Saharan Africa. Genetic control of Striga through resistance is widely considered to be the most practical and economically feasible method for long term control. The paper presents a comprehensive account of the Striga resistance mechanisms and environmental limitations to their usage in sub-Saharan Africa. Components of Striga resistance in cereals and legumes include low germination stimulant production, low haustorial initiation factor, mechanical barriers, incompatibility, antibiosis and Striga avoidance due to root growth habits. The successful exploitation of resistance has been limited by existence of specificity towards hosts, parasites that have evolved races specific host cultivars, Striga genetic variance which enables parasite to adapt to new resistance alleles and diverse hosts which support the parasite even in the absence of cereals together with low fertility due to nutrient mining in the smallholder sector. The results imply that different resistance mechanism may need to be present in genetically heterogeneous varieties or cereals with different resistance mechanisms may be rotated in the same field. Comprehensive Striga management systems should also address soil fertility in the small holder farmers of sub-Saharan Africa.

Willd (quinoa) is a crop that originated from the Andes and has been recently introduced in Zimbabwe so the agronomic performance is unknown yet. A 3-year field experiment was carried out at the Wo...

The jatropha plant was introduced to Zimbabwe in 1940. Until recently, jatropha production was mainly done by communal farmers in marginal areas of the country. Being a multipurpose tree, the jatropha plant was being used to produce soap, lubricants and in soil conservation. Due to the fuel crisis that gripped Zimbabwe over the last decade, there has been a move towards producing biodiesel to complement imported fossil fuel. There is potential to produce animal and plant protectants, and organic fertilizer from jatropha. The current utilization of the plant is limited by lack of a clear government policy, unfavorable selling prices and unavailable agronomic information. There is need for government to come up with a policy that encourages production, research and utilization of biofuels. Information on jatropha propagation should be made available, not only in English, but vernacular languages also. Research should be encouraged so that varieties that are higher yielding are produced.

Vegetable cultivation using river water, which may be polluted with heavy metals, can cause health problems to consumers. A study to establish cadmium and lead levels in water from Msasa, Manyame; Mukuvisi and Nyatsime Rivers was conducted in 2019. A questionnaire survey involving 105 randomly selected urban vegetable growers was conducted to examine farmer knowledge of the potential of polluted water to contaminate produce through heavy metals. Water, soil and vegetable samples were also collected and analysed for heavy metal presence using atomic absorption spectrophotometry. Results showed that some farmers (62%) were aware that wastewater could contain heavy metals. The majority of farmers (67%) applied phosphate-based fertilisers, a potential source of cadmium. Tested at P < 0.05, the results showed that sampled water from the four sites failed to meet the Standards Association of Zimbabwe 5560 (1997) standards. Cadmium tissue concentration from wastewater from Msasa and Manyame rivers was 1.3 and 1.17 mg g⁻¹ respectively, which were 59 and 65 times higher than 0.02 mg g⁻¹ from the control. Water from Manyame and Nyatsime rivers contains levels of heavy metals which exceed the Environmental Management Agency (EMA) safety guidelines. Farmers need to be educated on health hazards from contaminated wastewater. Enforcing regulations on effluent disposal, licencing of vegetable vendors and labelling of vegetables with information on source of water used to irrigate the crop can help reduce exposure of unsuspecting vegetable consumers.