Antibacterial effect of Artemisia and ginger extracts in controlling Agrobacterium tumefaciens in roses

Rose is the world’s most traded cut flowers with 74 % being produced in Kenya. Pests like spider mites, caterpillar, aphids, thrips, nematodes and diseases such as crown gall, downy mildew, powdery mildew and botrytis highly compromise rose production. Crown gall disease caused by Agrobacterium tumefaciens is the most problematic disease of roses in Kenya, causing a production loss of up to 60 % depending on the age and variety of rose. An experiment to determine the antibacterial effect of Artemisia and ginger extracts was carried out in vitro, where the inhibitory zones around filter discs soaked with extracts on Muller Hinton agar was established. The extracts were emulsified with dimethylsulfoxide (50 %) and minimum inhibitory concentrations of Artemisia (125 mg/ml), ginger (62.5 mg/ml) and mixture of Artemisia and ginger (31.25 mg/ml) were used to soak the filter discs whereas the commercial recommended rate of copper hydroxide of 6.25 mg/ml was used. Artemisia and copper hydroxide (commercial antibiotic) had highest inhibition zone of 12.80 mm compared to ginger 10.60 mm. A mixture of Artemisia and Ginger had a slightly lower inhibition zone (10.20 mm) though not significantly different from ginger (P> 0.001). An eight-month greenhouse experiment was also done to determine the efficacy of the extracts on inoculated rose plants. The results showed that crown gall incidence and gall weight were low but not significantly different from copper hydroxide and Artemisia. Crop vigor, which was indicated by stem length was highest for Artemisia treatment with an average of 73.54 cm followed by copper hydroxide (67.25 cm) while ginger and mixture of ginger and Artemisia had 53.44 cm and 64.70 cm respectively. From the results of this research, Artemisia and Ginger extracts are promising alternative to control crown gall and possibly other diseases in field crops. Artemisia performance compares well with copper hydroxide and therefore the best alternative to replace copper hydroxide

Assessing the Impact of Voluntary Certification Schemes on Future Sustainable Coffee Production

Coffee production faces major sustainability issues and consumers increasingly look to choose certified coffee as awareness grows. While consumers’ understanding of sustainability issues is limited, independent voluntary certification schemes such as Fairtrade, Rainforest Alliance, and certified organic—three high-profile schemes—can play a role in future-proofing coffee production through standard-setting. These schemes can also inform consumers about sustainability issues from economic, environmental, and social perspectives, thus driving up demand for sustainably grown coffee, and supporting an enabling environment for farmers and coffee-producing countries to improve the status quo. Sustainably grown coffee ensures that farmers sustain production while protecting the environment and the income that farmers rely on to maintain their livelihood. Based on a thematic analysis and synthesis of previous studies, this paper examines the social, economic, and environmental effects of voluntary certification schemes for coffee production. It evaluates the current state of coffee production and explores how certification schemes can be effective in encouraging more sustainable practices among producers. Three major voluntary certification schemes are evaluated to identify the impacts on producers, including key barriers and enablers to comply with sustainability standards and to determine how fit-for-purpose certification schemes are in assuring future sustainable coffee production

Elucidating the Potential of Native Rhizobial Isolates to Improve Biological Nitrogen Fixation and Growth of Common Bean and Soybean in Smallholder Farming Systems of Kenya

Identification of effective indigenous rhizobia isolates would lead to development of efficient and affordable rhizobia inoculants. These can promote nitrogen fixation in smallholder farming systems of Kenya. To realize this purpose, two experiments were conducted under greenhouse conditions using two common bean cultivars; Mwezi moja (bush type) and Mwitemania (climbing type) along with soybean cultivar SB 8. In the first experiment, the common bean cultivars were treated with rhizobia inoculants including a consortium of native isolates, commercial isolate (CIAT 899), a mixture of native isolates and CIAT 899, and a control with no inoculation. After 30 days, the crop was assessed for nodulation, shoot and root dry weights, and morphological features. In the second experiment, soybean was inoculated with a consortium of native isolates, commercial inoculant (USDA 110), and a mixture of commercial and native isolates. Remarkably, the native isolates significantly ( < 0.001) increased nodulation and shoot dry weight across the two common bean varieties compared to the commercial inoculant, CIAT 899. Mixing of the native rhizobia species and commercial inoculant did not show any further increase in nodulation and shoot performance in both crops. Further field studies will ascertain the effectiveness and efficiency of the tested indigenous isolates

Contrasting effects of cover crops on 'hot spot' arbuscular mycorrhizal fungal communities in organic tomato

Arbuscular mycorrhizal fungal (AMF) communities are fundamental in organic cropping systems where they provide essential agro-ecosystem services, improving soil fertility and sustaining crop production. They are affected by agronomic practices, but still, scanty information is available about the role of specific crops, crop rotations and the use of winter cover crops on the AMF community compositions at the field sites. A field experiment was conducted to elucidate the role of diversified cover crops and AMF inoculation on AMF diversity in organic tomato. Tomato, pre-inoculated at nursery with two AMF isolates, was grown following four cover crop treatments: Indian mustard, hairy vetch, a mixture of seven species and a fallow. Tomato root colonization at flowering was more affected by AMF pre-transplant inoculation than by the cover crop treatments. An enormous species richness was found by morphological spore identification: 58 AMF species belonging to 14 genera, with 46 and 53 species retrieved at the end of cover crop cycle and at tomato harvest, respectively. At both sampling times, AMF spore abundance was highest in hairy vetch, but after tomato harvest, AMF species richness and diversity were lower in hairy vetch than in the cover crop mixture and in the mustard treatments. A higher AMF diversity was found at tomato harvest, compared with the end of the cover crop cycle, independent of the cover crop and pre-transplant AMF inoculation. Our findings suggest that seasonal and environmental factors play a major role on AMF abundance and diversity than short-term agronomic practices, including AMF inoculation. The huge AMF diversity is explained by the field history and the Mediterranean environment, where species characteristic of temperate and sub-tropical climates co-occur

Application of residue, inorganic fertilizer and lime affect phosphorus solubilizing microorganisms and microbial biomass under different tillage and cropping systems in a Ferralsol

Reduced tillage increased microbial biomass and abundance of P solubilizers. Inorganic fertilisers reduced phosphorus solubilizing microbial abundance. Residue addition increased soil microbial biomass and abundance of P solubilizers. Intercropping increased microbial biomass and phosphorus solubilizers’ abundance. Liming reduced phosphorus solubilizing microbial species richness

Crop Diversification: A Potential Strategy To Mitigate Food Insecurity by Smallholders in Sub-Saharan Africa

As of 2010, about 239 million people in sub-Saharan Africa (SSA) were projected to be undernourished. With this figure expected to rise, concerted efforts to boost food production at the realm of global challenges such as climate instability and decline of nonrenewable resources are imperative. Food production in SSA presently faces the unprecedented challenge of producing sufficient and healthy food for the surging human population, while seeking to conserve the environment and reduce the use of nonrenewable resources and energy. Although over the past half century conventional agriculture has generally improved agricultural production in many parts of the world, this has come at high economic and environmental costs since intensive agriculture relies heavily on off-farm inputs. Conventional agriculture is also dependent on the use of specific crop varieties or hybrids that have been bred specifically to exploit high-input conditions. Conversely, crop varieties used in high-input systems are not often adapted to low-input farming, a key element of many smallholder farming systems. The exploitation of crop genetic diversity as a strategy to increase food production by smallholders in SSA and elsewhere in the world has not been critically examined. This aspect may provide new insights to global food insecurity since crop diversification is a fundamental tool for improving yield stability and crop resilience under changing climatic conditions

Upscaling Arbuscular Mycorrhizal Symbiosis and Related Agroecosystems Services in Smallholder Farming Systems

Smallholder farming systems form unique ecosystems that can protect beneficial soil biota and form an important source of useful genetic resources. They are characterized by high level of agricultural diversity mainly focused on meeting farmers’ needs. Unfortunately, these systems often experience poor crop production mainly associated with poor planning and resource scarcity. Soil fertility is among the primary challenges faced by smallholder farmers, which necessitate the need to come up with affordable and innovative ways of replenishing soils. One such way is the use of microbial symbionts such as arbuscular mycorrhizal fungi (AMF), a beneficial group of soil microbiota that form symbiotic associations with majority of cultivated crops and play a vital role in biological soil fertility, plant nutrition, and protection. AMF can be incorporated in smallholder farming systems to help better exploit chemical fertilizers inputs which are often unaffordable to many smallholder farmers. The present review highlights smallholder farming practices that could be innovatively redesigned to increase AMF symbiosis and related agroecosystem services. Indeed, the future of global food security depends on the success of smallholder farming systems, whose crop productivity depends on the services provided by well-functioning ecosystems, including soil fertility

Elucidating the Potential of Native Rhizobial Isolates to Improve Biological Nitrogen Fixation and Growth of Common Bean and Soybean in Smallholder Farming Systems of Kenya

Identification of effective indigenous rhizobia isolates would lead to development of efficient and affordable rhizobia inoculants. These can promote nitrogen fixation in smallholder farming systems of Kenya. To realize this purpose, two experiments were conducted under greenhouse conditions using two common bean cultivars; Mwezi moja (bush type) and Mwitemania (climbing type) along with soybean cultivar SB 8. In the first experiment, the common bean cultivars were treated with rhizobia inoculants including a consortium of native isolates, commercial isolate (CIAT 899), a mixture of native isolates and CIAT 899, and a control with no inoculation. After 30 days, the crop was assessed for nodulation, shoot and root dry weights, and morphological features. In the second experiment, soybean was inoculated with a consortium of native isolates, commercial inoculant (USDA 110), and a mixture of commercial and native isolates. Remarkably, the native isolates significantly (p<0.001) increased nodulation and shoot dry weight across the two common bean varieties compared to the commercial inoculant, CIAT 899. Mixing of the native rhizobia species and commercial inoculant did not show any further increase in nodulation and shoot performance in both crops. Further field studies will ascertain the effectiveness and efficiency of the tested indigenous isolates

Soil management practices affect arbuscular mycorrhizal fungi propagules, root colonization and growth of rainfed maize

Agronomic management practices influence beneficial soil biota, especially arbuscular mycorrhizal fungi (AMF). AMF colonizes about eighty percent of land plants, promoting absorption of essential nutrients and crop growth. Here, a 5-year field experiment was carried out in Central Kenyan Highlands to determine the effect of tillage, mulching and inorganic fertilizers on the number of infective AMF propagules in the soil, mycorrhizal root colonization of maize and uptake of P and N from the soil. The study involved conventional and minimum tillage systems, mulching using dried maize stovers and inorganic fertilizers (120 kg N/ha). The experiment was set up in randomized complete block design and replicated thrice. The number of infective AMF propagules decreased in the following order; V4 stage (p &lt; 0.0001), V6 stage (p &lt; 0.0001), maize harvest (p = 0.0076) and before maize planting (p = 0.0061). Minimum tillage + mulch + no NP fertilizer (ZRO) treatment recorded the highest number of infective AMF propagules with an average of 90 propagules g-1 of soil whereas conventional tillage + mulch + NP fertilizer (CRF) and conventional tillage + no mulch + NP fertilizer (CWF) treatments recorded the lowest number of AMF propagules with an average of 1.33 propagules g-1 of soil. Besides, AMF colonization of maize roots at V4, V6 and harvest stages was significantly affected by tillage (p &lt; 0.0001), mulch (p = 0.0001) and fertilizer (p &lt; 0.0001). Results at juvenile stage showed a strong positive correlation between AMF colonization and shoot P (r = 0.933, p &lt; 0.0001) and N (r = 0.928, p &lt; 0.0001). These findings demonstrate a strong effect of agronomic management practices on soil AMF propagules which subsequently affected root colonization and uptake of essential nutrients such as P and N