18 research outputs found
On-farm comparison of different postharvest storage technologies in a maize farming system of Tanzania Central Corridor
Article purchased; Published online: 16 March 2018Seven methods for storing maize were tested and compared with traditional storage of maize in polypropylene bags. Twenty farmers managed the experiment under their prevailing conditions for 30 weeks. Stored grain was assessed for damage every six weeks. The dominant storage insect pests identified were the Maize weevil (Sitophilus zeamais) and the Red flour beetle (Tribolium castaneum). The moisture content of grain in hermetic conditions increased from 12.5 ± 0.2% at the start of storage to a range of 13.0 ± 0.2–13.5 ± 0.2% at 30 weeks. There was no significant difference (F = 87.09; P < 0.0001) regarding insect control and grain damage between hermetic storage and fumigation with insecticides. However, the insecticide treatment of polypropylene yarn (ZeroFly®) did not control the insect populations for the experimental period under farmers' management. Grain damage was significantly lower in hermetic storage and fumigated grain than ZeroFly® and polypropylene bags without fumigation. No significant difference in grain damage was found between airtight treatment alone and when combined with the use of insecticides. During storage, S. zeamais was predominant and could be of more economic importance than T. castaneum as far as maize damage is concerned. At 30 weeks, the germination rate of grain stored with insecticides or in hermetic storage (68.5 ± 3.6% to 81.4 ± 4.0%) had not significantly reduced from the rate before storage (F = 15.55; P < 0.0001) except in ZeroFly®, also in polypropylene bags without treatment. Even though such bags did not control storage pests, farmers still liked this cheap technology. Hermetic storage techniques can be recommended to farmers without the use of insecticides provided they are inexpensive, and the proper application of technologies is ensured
Rice value chain analysis in Tanzania: Identification of constraints, opportunities and upgrading strategies
The importance of rice ( Oryza sativa L.) as a food and cash crop in
Eastern Africa, is increasing, but its value chain is becoming complex.
In 2012/13, rice value chain analysis was conducted in rice farming
systems of Lake, Eastern and Southern-Highlands zones of Tanzania. A
sample of 240 producers, 60 traders and 30 processors was involved in
the study. The aim of this study was to enhance rice actors with
knowledge of the rice value chain, and identify feasible upgrading
strategies. The study results revealed that rice was staple crop for
more than 50% of the communities in Kilombero, Kyela and Mvomero
districts; and less than 30% in Rorya, Mbarali and Maswa districts. It
was also an important cash crop (79 - 100%) in all districts. About 44
and 61% of the total crop area cultivated per household, in lowland
rainfed and irrigated ecosystems, respectively were under rice
cultivation. SARO 5 was the only improved variety widely grown by 27%
of farmers out of 32 varieties. Rice yield ranged from 1.5 to 4.3 t
ha-1 and varied greatly by ecosystem and variety. About 61-93% of
farmers sold their rice paddy to collectors, used non-standard
measurements. Farmers profits ranged from US a 994.85 $ par hectare. La part des
producteurs varient de 34 a 40%. Ceci indique que des strategies de
modernisation sont necessaires et pourrait accroitre le revenue des
producteurs mais aussi ameliorer la competitivite de la filiere
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Livelihood diversification and the expansion of artisanal mining in rural Tanzania: drivers and policy implications
This paper provides an extended analysis of livelihood diversification in rural Tanzania, with special emphasis on artisanal and small-scale mining (ASM). Over the past decade, this sector of industry, which is labour-intensive and comprises an array of rudimentary and semi-mechanized operations, has become an indispensable economic activity throughout Sub-Saharan Africa, providing employment to a host of redundant public sector workers, retrenched large-scale mine labourers and poor farmers. In many of the region’s rural areas, it is overtaking subsistence agriculture as the primary industry. Such a pattern appears
to be unfolding within the Morogoro and Mbeya regions of southern Tanzania, where findings from recent research suggest that a growing number of smallholder farmers are turning to ASM for employment and financial support. It is imperative that national rural development programmes take this trend into account and provide support to these people
The importance of tropical root-knot nematodes (Meloidogyne spp.) and factors affecting the utility of Pasteuria penetrans as a biocontrol agent
The conclusions of a collaborative study of the occurrence and importance of root-knot nematodes (RKN, Meloidogyne spp,) and of their control agent, Pasteuria penetrans, in parts of Europe, Africa, South America and the Caribbean are presented. Root-knot nematodes were estimated to reduce the yields of a wide range of horticultural crops by > 25% in Ecuador, Malawi and Tanzania, and by ca 10% in Trinidad and Tobago. The greatest proportion of infected crops were observed in Ecuador (205 of 207) and the least in Trinidad and Tobago (70 of 174). The mean gall index was greatest in Ecuador (5.5). Levels of galling were least in Senegal (1.6), even though 89% of crops were infested and virulent M. mayaguensis was widespread. In all countries. M. incognita and M. javanica were the most abundant species, but M. hispanica occurred widely in Burkina Faso, even in newly cultivated areas in the Sahile. Several new esterase phenotypes were detected, especially in Ecuador and Malawi. Juveniles (J2) collected from the soil during the surveys were examined for attached spores of P. penetrans. It was widespread (20 to 60% of RKN populations). except in Malawi and Tanzania 8 to 5% for every increase of one in the gall index. Yields were increased by alternating tomato with leguminous crops in some trials, but not in others. It is proposed that, in natural infections, mutual selection produces a dynamic balance between the P. penetrans and the RKN whereby levels of infection are rarely suppressive. However, the introduction of an "exotic" isolate of P. penetrans, with a different attachment profile, can disturb this balance, resulting in a greatly increased proportion of infected J2 and females, increased yields of spores and more suppression of RKN populations.Peer reviewe
Thermal time and ecological strategies - a unifying hypothesis
Rates of embryogenesis and of development and growth in several nematodes are linearly related to temperature over a considerable range. On this basis, published data on the thermal time requirements are compared for a tropical and a temperate species of plant parasitic nematode Meloidogyne javanica and M. hapla respectively, the two being closely related and morphologically and biologically similar. M. hapla has a lower base temperature (T-b) and a higher thermal constant (S) than M. javanica with the relative values being almost inversed. Consequently, above their respective T-b values the slope of the relationship between rate of development and temperature was greater for the tropical species than that for the temperate species. A mathematical exploration of the relationship between T-b and S was made assuming that, over a narrow range, Tb X S was a constant. With this assumption, for any given average environmental temperature (T-e) the optimum base temperature for minimum developmental duration was T-e/2, and the temperature at which the duration of development was equal for the otherwise identical species was shown to be the sum of their base temperatures. The practical effect of the differences in T-b and S was to give M. hapla, the temperate species, a shorter life cycle and hence a competitive advantage at temperatures below 21 Angstrom C and M. javanica, the tropical species, the advantage above that temperature. It is argued that a negative correlation between T-b and S is likely to be widespread, and provides a mechanism for regulating the distributions of related, competing organisms. Support for the hypothesis that the value of S tends to decrease as T-b increases is derived from data on the embryogenesis of an animal parasitic nematode Haemonchus contortus and from seed germination studies. Contrary results and exceptions are also briefly discussed. The observed interaction between T-b and S may be fundamental to many poikilothermic organisms and plants and provides an explanation for tropical species generally having higher T-b values than temperate ones. The ecological implications of different values of T-b and of S, including their relationship with organisms which are ''r'' or ''K'' strategists are briefly discussed
Nematicidal Activity of Mint Aqueous Extracts against the Root-Knot Nematode Meloidogyne incognita
The nematicidal activity and chemical characterization of aqueous extracts and essential oils of three mint species, namely, Mentha × piperita, Mentha spicata, and Mentha pulegium, were investigated. The phytochemical analysis of the essential oils was performed by means of GC-MS, whereas the aqueous extracts were analyzed by LC-MS. The most abundant terpenes were isomenthone, menthone, menthol, pulegone, and carvone, and the water extracts yielded mainly chlorogenic acid, salvianolic acid B, luteolin-7-O-rutinoside, and rosmarinic acid. The water extracts exhibited significant nematicidal activity against Meloidogyne incognita, and the EC50/72h values were calculated at 1005, 745, and 300 mg/L for M. × piperita, M. pulegium, and M. spicata, respectively. Only the essential oil from M. spicata showed a nematicidal activity with an EC50/72h of 358 mg/L. Interestingly, menthofuran and carvone showed EC50/48h values of 127 and 730 mg/L, respectively. On the other hand, salicylic acid, isolated in the aqueous extracts, exhibited EC50 values at 24 and 48 h of 298 ± 92 and 288 ± 79 mg/L, respectively