Promotion of Labour Saving Rice Mechanization Technologies in Rain-Fed Low Land and Irrigated Ecologies of Tanzania and Kenya

Rice farming has been conducted in both Tanzania and Kenya mostly under manual operations and has resultedin low outputs due to inefficient production methods. This has resulted into reduced acreage, low yields andlabour drudgery. To increase efficiency in agricultural production among small scale farmers, mechanization wasfound to be the main driving tool. Research on mechanizing rice production activities from land preparation tothreshing was conducted in irrigated and rain fed ecologies of Mbarali and Kyela respectively while in irrigatedsystem of Mvomero Morogoro only herbicide effectiveness in weeds control was assessed. Seed treatment wasassessed in irrigated ecology of Mwea, Kenya. Randomized Complete Block Design (RCBD) was employed indemonstration plots to assess different rice mechanization technologies. Ploughing and puddling using powertiller, oxen and hand hoe were determined in terms of man-days required. Direct rice seeding and transplantingusing a walk behind motorized planter and transplanter were also compared against hand seeding andtransplanting respectively. Research results indicated that there were significant differences (P < 0.05) for mostmechanized operations along the rice production value chain. In order for rice growing farmers to realize thebenefits accrued from mechanizing rice production, all levels of production should be mechanized. However forrice mechanization to be successful rice mechanization machines and implement should be subsidized to enablemajority of smallholder farmers to access them. Smallholder farmers need also to be mobilized into groups forease acquisition of rice machines and capacity building.Keywords: Puddling, Transplanting, Threshin

Fertilisers differentially affect facultative and obligate parasitic weeds of rice and only occasionally improve yields in infested fields

Different fertilisers were field tested to investigate whether they (1) suppress the obligate parasitic weed Striga asiatica and the facultative parasitic weed Rhamphicarpa fistulosa, and (2) favour rainfed rice yields under parasitic weed infestation. Four years of experiments were conducted in southwest Tanzania, in a S. asiatica-infested rainfed upland and a R. fistulosa-infested rainfed lowland field. Treatments included sole mineral (NPK or Di-Ammonium Phosphate —DAP— plus urea), organic (cattle manure or rice husk), combinations of mineral and organic fertilisers and a no-fertiliser control. Fertilisers moderately suppressed the obligate parasite S. asiatica, but no correlations between infestation level and soil fertility status were observed. In the lowland field, fertilisers promoted the facultative R. fistulosa, in particular the ones that included organic components. Plant-available phosphorus, exchangeable potassium and soil organic matter content correlated with R. fistulosa infestation levels. Positive fertiliser effects on yields were found in both parasitic weed infested fields, except in years with high S. asiatica infestation levels. Rice husks alone and rice husks or manure combined with DAP and urea increased yields and soil fertility most. We conclude that fertilisation differentially affects the obligate and facultative parasitic weeds of rice systems; obligate parasites may be slightly suppressed, but facultative parasites may even be stimulated. Meanwhile, consistent rice yield increases under parasitic weed infested conditions cannot be obtained with fertiliser application when parasitic weed infestation levels are too high

Systems approaches to innovation in pest management: reflections and lessons learned from an integrated research program on parasitic weeds in rice

This paper provides a retrospective look at a systems-oriented research program, on the increasing occurrence of parasitic weeds in rainfed rice in sub-Saharan Africa, to qualitatively assess merits and identify challenges of such approach. We gained a broad contextual overview of the problem and different stakeholders' roles, which enabled identification of entry points for innovations in parasitic weed management. At the crop level parasitic weed infestation is associated with poor soil fertility and water management. Farmers' infrequent use of inputs to control them was caused by various factors, ranging from fears of undesired side effects (agronomic) to a lack of quality control of products (institutional). Furthermore, there may be enough extension agents, but they lack the required training on (parasitic) weed management to provide farmers with advice, while their organizations do not provide them with the necessary means for farm visits. At even higher organizational levels we observed a lack of coherent policies on parasitic weed control and implementation of them. Merits and challenges of an integrated multi-stakeholder and multi-level research project are discussed

Do NERICA rice cultivars express resistance to Striga hermonthica (Del.) Benth. and Striga asiatica (L.) Kuntze under field conditions?

The parasitic weeds Striga asiatica and Striga hermonthica cause high yield losses in rain-fed upland rice in Africa. Two resistance classes (pre- and post-attachment) and several resistant genotypes have been identified among NERICA (New Rice for Africa) cultivars under laboratory conditions (in vitro) previously. However, little is known about expression of this resistance under field conditions. Here we investigated (1) whether resistance exhibited under controlled conditions would express under representative Striga-infested field conditions, and (2) whether NERICA cultivars would achieve relatively good grain yields under Striga-infested conditions. Twenty-five rice cultivars, including all 18 upland NERICA cultivars, were screened in S. asiatica-infested (in Tanzania) and S. hermonthica-infested (in Kenya) fields during two seasons. Additionally, a selection of cultivars was tested in vitro, in mini-rhizotron systems. For the first time, resistance observed under controlled conditions was confirmed in the field for NERICA-2, -5, -10 and -17 (against S. asiatica) and NERICA-1 to -5, -10, -12, -13 and -17 (against S. hermonthica). Despite high Striga-infestation levels, yields of around 1.8 t ha−1 were obtained with NERICA-1, -9 and -10 (in the S. asiatica-infested field) and around 1.4 t ha−1 with NERICA-3, -4, -8, -12 and -13 (in the S. hermonthica-infested field). In addition, potential levels of tolerance were identified in vitro, in NERICA-1, -17 and -9 (S. asiatica) and in NERICA-1, -17 and -10 (S. hermonthica). These findings are highly relevant to rice agronomists and breeders and molecular geneticists working on Striga resistance. In addition, cultivars combining broad-spectrum resistance with good grain yields in Striga-infested fields can be recommended to rice farmers in Striga-prone areas

RAAIS: Rapid Appraisal of Agricultural Innovation Systems (Part I). A diagnostic tool for integrated analysis of complex problems and innovation capacity

This paper introduces Rapid Appraisal of Agricultural Innovation Systems (RAAIS). RAAIS is a diagnostic tool that can guide the analysis of complex agricultural problems and innovation capacity of the agricultural system in which the complex agricultural problem is embedded. RAAIS focuses on the integrated analysis of different dimensions of problems (e.g. biophysical, technological, socio-cultural, economic, institutional and political), interactions across different levels (e.g. national, regional, local), and the constraints and interests of different stakeholder groups (farmers, government, researchers, etc.). Innovation capacity in the agricultural system is studied by analysing (1) constraints within the institutional, sectoral and technological subsystems of the agricultural system, and (2) the existence and performance of the agricultural innovation support system. RAAIS combines multiple qualitative and quantitative methods, and insider (stakeholders) and outsider (researchers) analyses which allow for critical triangulation and validation of the gathered data. Such an analysis can provide specific entry points for innovations to address the complex agricultural problem under study, and generic entry points for innovation related to strengthening the innovation capacity of agricultural system and the functioning of the agricultural innovation support system. The application of RAAIS to analyse parasitic weed problems in the rice sector, conducted in Tanzania and Benin, demonstrates the potential of the diagnostic tool and provides recommendations for its further development and use

Addressing current and future problems of parasitic weeds in rice

Significant areas of rain-fed rice in the Sahel, savannah nd derived savannah zones of sub-Saharan Africa (SSA), Madagascar and other Indian Ocean Islands are infested by parasitic weeds. The affected area accommodates some of the poorest farmers of the world. Without appropriate management parasitic weeds in rice are expected to increase in importance in SSA due to their general invasive nature and their abilities to adapt to changing conditions such as imposed by predicted climate changes. The most important parasitic weeds in rice are: Striga hermonthica, Striga asiatica, Striga aspera and Rhamphicarpa fistulosa. The first two are primarily found in free-draining uplands while S. aspera is also found on hydromorphic soils and R. fistulosa is restricted to unimproved lowlands including inland valleys. As parasitic weeds are typical production constraints in subsistence rice production, targeting them would directly contribute to poverty alleviation and food security. This paper provides an overview of the problems caused by parasitic weeds in rice and discusses management options and opportunities for research for development

Rice yields under Rhamphicarpa fistulosa-infested field conditions, and variety selection criteria for resistance and tolerance

The facultative parasitic weed Rhamphicarpa fistulosa, is a widespread problem in rain-fed rice production systems in Africa. Little is known about rice varietal differences in infection level and yields in fields infested by this root hemi-parasite. During three cropping seasons (2012–2014), an experiment was conducted to address these knowledge gaps and to identify suitable variety selection criteria for R. fistulosa resistance and tolerance. Sixty-four adapted lowland rice varieties, including all interspecific lowland varieties of NERICAs, their most common parents – IR64 and TOG5681 – and two locally popular varieties – Mwangulu and Supa India – were grown in an R. fistulosa-infested field in southern Tanzania. As expected from a facultative parasite, host plant varieties had no effect on R. fistulosa numbers. Consistent varietal differences in R. fistulosa biomass were however observed, with no Year × Variety effects, and this parameter can therefore be used to select for resistance. Parasite-free observation plots were established in the last year. Due to the facultative nature of the parasite, creating such R. fistulosa-free plots was simply obtained by regular early weeding. The presence of parasite-free control plots enabled assessment of worthwhile additional information such as parasite-free yield, parasite-inflicted yield losses (RYLR) and varietal differences in tolerance. Under R. fistulosa-infested conditions (3-season averages, no Year × Variety interaction effect), rice grain yields ranged from 1.2 t ha−1 for the worst performing variety (TOG5681) to 2.4 t ha−1 for the best performing varieties (NERICA-L-39, -20). Under R. fistulosa-free conditions (2014 only) rice grain yields ranged from 2.4 (NERICA-L-22) to 5.4 t ha−1 (NERICA-L-17). Tolerant varieties were characterized by a low RYLR and a high parasite biomass (e.g. Supa India, NERICA-L-20). The selection measures identified are effective, easy and practical under field conditions. They facilitated identification of thirteen varieties with high resistance, sixteen varieties with low RYLR and two varieties with high tolerance. These varieties would be invaluable for future rice breeding programs. For farmers in R. fistulosa-endemic areas the most promising varieties are probably NERICA-L-40 and -31, as they combine good yields under infested conditions with low levels of parasite infection

From rice-like plants to plants liking rice: a review of research on weeds and their management in African rice systems

Competition from weeds is the most important yield reducing factor in African rice production systems. Generally important weed management practices in rice are controlled flooding and the use of herbicides. Smallholder rice farmers in Africa however often lack the necessary water management infrastructure, access to affordable, good quality herbicide products and knowledge and equipment for their safe and effective application. Against this challenging backdrop, effective and affordable weed management strategies are highly needed. The literature on weed ecology and management in African rice systems is systematically reviewed to assess achievements in the last quarter of the past 50 years of international rice research endeavours, the period since the last comprehensive review (2009), and to propose the way forward for research and development. Most published studies are from West Africa and focussed on rainfed upland (43% of all relevant studies) or rainfed lowland (32%) rice. Grasses are the most frequently studied weed types, closely followed by parasitic weeds and broadleaved weeds (ex aequo). Most research (75% of published studies) focussed on weed management, mostly referring to or including curative measures (e.g., chemical, manual) or preventive weed management options that improve weed competitiveness of the crop (e.g., crop establishment, cultivars), while less attention was observed for preventive measures aiming at reduced weed recruitment or seed bank sizes (e.g., crop rotations, intercropping, mulches) or integrated weed management approaches. Future research should invest more in developing integrated weed management strategies that achieve (1) reduced weed recruitment, (2) reduced weed seed bank sizes and (3) improved crop competitiveness and that are compatible with farmer's production resources, fairly independent of (agrochemical) industries and markets and benign to the environment and human health. We recommend research on parasitic weeds to focus on a further broadening of the range of currently available management options, with a particular focus on the role of soil fertility and more efficient fertiliser technologies that simultaneously improve crop productivity and quality. For research to contribute to the development of meaningful weed management strategies for African rice systems in the future, we believe it would be best to identify and focus on target-location specific weed-communities, and to reconcile field level weed management strategies with the preconditions set at higher system levels (e.g., farming and agricultural systems) and anticipated scenarios regarding changing demographics and biophysical and institutional environments

Participatory appraisal of institutional and political constraints and opportunities for innovation to address parasitic weeds in rice

Parasitic weeds in smallholder rice production systems, of which Striga asiatica, Striga hermonthica and Rhamphicarpa fistulosa are the main representatives, form an increasing problem for food and income security in sub-Saharan Africa (SSA). The objective of this paper is to identify institutional and political constraints and opportunities for innovation to address parasitic weed problems in rice. Constraints and opportunities for innovation were studied across three nested systems: the parasitic weed control system, the crop protection system, and the agricultural system. Multi-stakeholder workshops, interviews and surveys were held to gather data on key constraints faced by different stakeholder groups across three parasitic weed infested study sites in both Tanzania and Benin. The results demonstrate that in both countries, the majority of institutional and political constraints relate to the functioning of the broader crop protection and agricultural systems and not specifically to parasitic weeds. Although differences were observed between the two countries and the different stakeholder groups, the majority of constraints perceived by the stakeholders were caused by a lack of capabilities and resources and a limited access to credit. Awareness raising of parasitic weed problems among farmers, extension and crop protection officers at the local level, combined with improved input and service supply and enhanced agricultural education and training curricula at the national level, were identified as important elements for improvement. More structural collaboration between key stakeholder groups is expected to contribute to a better recognition of agricultural problems, like that of parasitic weeds in rice, and a more timely identification of feasible solutions

RAAIS: Rapid Appraisal of Agricultural Innovation Systems (Part II). Integrated analysis of parasitic weed problems in rice in Tanzania

Parasitic weeds such as Striga spp and Rhamphicarpa fistulosa in smallholder rice production systems form an increasing problem for food and income security in sub-Saharan Africa. In this paper we implement the Rapid Appraisal of Agricultural Innovation Systems (RAAIS) as a diagnostic tool to identify specific and generic entry points for innovations to address parasitic weeds in rain-fed rice production in Tanzania. Data were gathered across three study sites in Tanzania where parasitic weeds are eminent (Kyela, Songea Rural and Morogoro Rural districts). The results demonstrate that in Tanzania, weeds in general and parasitic weeds in particular receive little attention in agricultural research, training and education curricula. Crop protection policies mainly focus on the control of (insect) pest and diseases and there is relatively little attention for weed prevention, which is essential for addressing parasitic weed problems effectively. Specific entry points for innovation include increasing awareness of parasitic weed problems among farmers, extension and crop protection officers and policymakers. In regions where awareness is relatively high, participatory research approaches can provide a basis for developing locally adapted parasitic weed management strategies. Generic entry points for innovation include enhanced collaboration and interaction between stakeholders across different levels, for example in multi-stakeholder platforms. This can provide the basis for developing and implementing coherent policy and development strategies to address structural constraints in the agricultural system, including the promotion of clean local seed systems, investments in physical and knowledge infrastructure development, adequate backstopping of agricultural extension officers, agribusiness training for farmers, quality control of agricultural inputs, timely access to agricultural inputs, and improved access to markets for farmers. Together the specific and generic entry points can strengthen the innovation capacity of Tanzania's agricultural system to address parasitic weed problems, as well as other complex agricultural problems