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Effect of Rhizobium Inoculation and Supplementation with Phosphorus and Potassium on Growth and Total Leaf Chlorophyll (Chl) Content of Bush Bean Phaseolus vulgaris, L.  [PDF]
Abdulkadir Mfilinge, Kelvin Mtei, Patrick Ndakidemi
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.514152
Abstract: The study was conducted to investigate the effect of Rhizobium inoculation and supplementation of phosphorus and potassium on growth and total leaf chlorophyll content to the three released bush bean varieties in northern Tanzania. To achieve this aim, the glasshouse experiment was conducted at Nelson Mandela African Institution of Science and Technology while field experiment were carried out at Tanzania Coffee Research Institute, in Kilimanjaro, Tanzania between April-July 2014. The experiment was laid out in factorial arrangement. Factor I comprised of three bush bean varieties. Factor II involved two inoculation treatments viz 1) inoculation with Rhizobium spp. and 2) without inoculation. Factor III included four fertilizer levels (0 Kg·ha-1 20 Kg K ha-1, 30 Kg P ha-1 and 20 kg·K + 30 Kg P ha-1). Both screen house and field experiments were replicated four times. Plant growth parameters (plant height (cm), number leaves per plant, stem girth (mm)) were measured at 2, 4 and 6 weaks after planting (WAP). The chlorophyll was extracted by using Dimethylsulphoxide (DMSO) and absorbance was determined at 645 and 663nm using UV/Visible spectrophotometer. Results showed that Rhizobium application significantly improved the number of leaves per plant, plant height, pant girth and total leaf chlorophyll content. Furthermore, compared with the zero treatment control, potassium fertilization significantly increased the number of leaves per plant, plant height, pant girth and total leaf chlorophyll content of the three varieties. In general, these parameters were significantly increased with phosphorus supplied at 30 kg/ha. The combination of these supplies at different levels resulted in significant interactions in some parameters and thus indicating need for these inputs in the study area.

The Potential of Common Beneficial Insects and Strategies for Maintaining Them in Bean Fields of Sub Saharan Africa  [PDF]
Baltazar Ndakidemi, Kelvin Mtei, Patrick A Ndakidemi
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.73036
Abstract: Beneficial insects provide natural ecosystem services such as biological control of pests, soil formation, nutrient cycling and pollination of plants. Beneficial insects include pollinators important in the essential pollination process of all plants, and natural enemies of pests such as parasitoids and predators which are important in the suppression of pest damage to crops. Knowledge on management techniques to attract beneficial insects in the agricultural fields is a way forward to enhance agro ecosystems for increased crop production. Therefore, proper understanding and identification of natural enemies, as well as pollinators in agricultural fields, is essential in promoting biological control and pollination activity. Natural enemies and pollinators, within legume fields, play a key role in ensuring sustainable production, especially in smallholder farms. There is a limited understanding of beneficial insects and the ecosystem services they offer to the agricultural production process in much of sub-Saharan Africa. This paper reviewed and provided existing knowledge on beneficial insects in bean fields. This will give the basis for research on beneficial insects in bean fields and practices that encourage their populations.
Impacts of Synthetic and Botanical Pesticides on Beneficial Insects  [PDF]
Baltazar Ndakidemi, Kelvin Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.76038
Abstract: Sustainable methods to control insect pests that affect crop yield have become a great challenge to mainly smallholder farmers. Beneficial insects in agricultural fields play an important role in natural pest control and pollination. The use of synthetic and botanical pesticides has detrimental effects to both natural enemies and pollinators in agricultural fields. The pesticides affect the survival of a range of life cycle stages, reductions in reproductive capacity, changes in the suitability of hosts for parasitising or predation, reduced emergence of parasitoids from sprayed host eggs and cause direct mortality. This has caused a serious menace to biological control agents and pollinators. When natural enemies are reduced, even more serious consequences may result for pest population dynamics which include the phenomena of resurgence and eruption of secondary pests. The decrease in pollinators reduces agricultural productivity. This review aims at exploring the side effects of synthetic and botanical pesticides on beneficial insects to give the basis for research on the negative impacts of synthetic and botanical pesticides on these insects. This information will assist in optimizing the use of pesticides in integrated pest management programmes by employing more sustainable and ecosystem benign practices such as the use of right dosage and selective pesticides in agricultural fields.
Isolation and Molecular Characterization of Elite Indigenous Rhizobia Nodulating Phaseolus bean (Phaseolus vulgaris L.)  [PDF]
Yusuph Namkeleja, Kelvin Mtei, Patrick A. Ndakidemi
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.714175
Abstract: Nowadays application of biological nitrogen fixation (BNF) through rhizobia inoculums is highly promoted as a solution to solve the problem of poor soil fertility in areas where legumes are cultivated. This is due to the fact that, rhizobia enhance nitrogen fixation, induce disease resistance, reduce heavy metal in the soil, facilitate bioavailabity of iron in soil and is environmental friendly. To get rhizobia strains which are suitable for inoculants production, isolation and molecular characterization of elite rhizobia are highly needed. Molecular characterization acts as a spark plug for discovery of many microbes including Rhizobia. Multi Locus Sequence Analysis (MLSA), 16S rRNA gene sequence analysis, DNA-DNA hybridization and SDS-PAGE analysis of the whole-cell proteins are the molecular techniques mostly used in characterizing rhizobia. But before deciding to use or not to use rhizobia inoculants in certain areas, knowing the population size of indigenous rhizobia found in that area is very important, because this is a major factor which determines inoculums responses as well gives clues on which areas need or do not need inoculation. The Most Probable Number (MPN) method is mostly used in enumerating rhizobia population of the soil. Given that, in most of the developing countries, including Tanzania, Biological Nitrogen Fixation (BNF) technology is not fully flourished; more efforts in isolation, molecular characterization of elite rhizobia and estimation of indigenous rhizobia population in various areas are required.
Extrapolations on the Use of Rhizobium Inoculants Supplemented with Phosphorus (P) and Potassium (K) on Growth and Nutrition of Legumes  [PDF]
George W. Mmbaga, Kelvin M. Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.512130
Abstract: Land scarcity and poor farming management practices has resulted in to intensive agriculture which rendered most of the soil in sub Saharan Africa depleted in essential plant nutrients. High prices of chemical fertilizer are crucial bottleneck toward increasing production of legumes and other food crops in most countries found in sub-Saharan Africa. Nitrogen, phosphorus and potas-sium are among the most limiting nutrients for plant growth as they play different but crucial roles in the plant physiological processes. These macronutrients are fundamental components of cell building blocks including genes and chromosomes. This review intend to show the vital roles played by rhizobial inoculants supplemented with phosphorus and potassium in enhancing growth, yield, photosynthesis, nodulation, nutrient uptake and nitrogen fixation of legumes.
Prospective Bioactive Compounds from Vernonia amygdalina, Lippia javanica, Dysphania ambrosioides and Tithonia diversifolia in Controlling Legume Insect Pests  [PDF]
Regina W. Mwanauta, Kelvin A. Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.512123
Abstract: Synthetic insecticides are widely known to control insect pest, but due to high operational cost, environmental pollution, toxicity to humans, harmful effect on non-target organisms and the development of insect resistance to this products, have created the need for developing alternative such as those involving the use of botanical pesticides to control insect pest. Bioactive compounds derived from plant could be an alternative source for insect pest control because they constitute a rich source of natural chemicals. This review aims to explore the potential of plant bioactive compounds from Vernonia amygdalina, Lippia javanica, Dysphania ambrosioides and Tithonia diversifolia as a low-cost, safe and environmentally friendly means of controlling insect pests in legumes.
Isolation and Characterization of Nitrogen Fixing Rhizobia from Cultivated and Uncultivated Soils of Northern Tanzania  [PDF]
Zephania Simon, Kelvin Mtei, Amare Gessesse, Patrick A. Ndakidemi
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.526423
Abstract: Soil bacteria1 called rhizobia are gram-negative capable to colonize the soil immediately surrounding roots under the influence of the plant “rhizosphere” and reduce atmospheric nitrogen into the form available to plants through nitrogen fixation process. Nitrogen is the most limiting and supplied nutrient to most plants, and the determinant of plant growth. Legumes differ with most plants because they have access to nitrogen from both mineral and symbiotic sources. Small-scale farmers who are the major legume producers in Africa rarely apply fertilizers during legume production. Hence, the crop is largely dependent on fixed nitrogen from native nitrogen fixers. Isolation of rhizobia for legume production has been given a little attention in Africa due to inadequate research or negligence of researchers and unawareness of its potential in legume production as well as lack of an intention from skilled personnel to popularize the technology. Evaluation of effectiveness of isolated rhizobia is essential for inoculants preparation, host specificity recommendation and symbiotic effectiveness. The isolation, determination of their population in the soil and assessing factors affecting their population and testing the effectiveness of native nitrogen fixers with respect to right trap host crop are given a special attention in this review.
Potential of Controlling Common Bean Insect Pests (Bean Stem Maggot (Ophiomyia phaseoli), Ootheca (Ootheca bennigseni) and Aphids (Aphis fabae)) Using Agronomic, Biological and Botanical Practices in Field  [PDF]
Regina W. Mwanauta, Kelvin M. Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.65048
Abstract: Common bean production in Africa suffers from different constrains. The main damage is caused by insect pest infestations in the field. The most common insects pests which attack common bean in the field are the bean stem maggot (Ophiomyia phaseoli), ootheca (Ootheca bennigseni) and aphids (Aphis fabae). Currently, few farmers in Africa are using commercial pesticides for the control of these insect pests. Due to the negative side effects of commercial pesticides to human health and the environment, there is a need for developing and recommending alternative methods such as those involving agronomic and botanical/biological measures in controlling common bean insect pests. This review aim to report the most common insects pests which attack common bean (Phaseolus vulgaris L.) in the field and explore the potential of agronomic, biological and botanical methods as a low-cost, safe and environmentally friendly means of controlling insect pests in legumes.
Yield and Fiscal Benefits of Rhizobium Inoculation Supplemented with Phosphorus (P) and Potassium (K) in Climbing Beans (Phaseolus vulgaris L.) Grown in Northern Tanzania  [PDF]
George W. Mmbaga, Kelvin M. Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.68076
Abstract: Both field and green house experiments were intended to investigate and evaluate the outcome of rhizobial inoculation supplemented with P and K on climbing beans production in northern Tanzania. The results obtained indicated that, inoculation using Rhizobium inoculants supplemented with fertilizers significantly (p ≤ 0.001) improved both vegetative and yield parameters of climbing beans varieties compared with control treatment. The economic analysis in rhizobium alone revealed a profit of US$ 2350 compared with control treatment with US$ 1558 profit, which was finally reflected in higher percentage increase over control and higher marginal rate of return (MRR). Thus, the use of Rhizobium inoculants supplemented with P and K increased climbing beans yield and the economic analysis performed based on total revenue and variable costs reflected an improvement in economic well being of a small hold farmer of northern Tanzania.
The Toxicity, Persistence and Mode of Actions of Selected Botanical Pesticides in Africa against Insect Pests in Common Beans, P. vulgaris: A Review  [PDF]
Nelson Mpumi, Kelvin Mtei, Revocatus Machunda, Patrick A. Ndakidemi
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.71015
Abstract: Common beans are affected by many insect pests such as bean leaf beetle, aphids, legume pod borer and bean beetles. Traditional and cultural practices such as site selection, crop rotation, intercropping and seed selection, sowing date are used to reduce the infestation of insect pests of common beans in the field and in storage rooms. Natural enemies such as predators, parasitoids and pathogens can control the insect pests. Synthetic pesticides such as cypermethion, carbaryl, and lambda-cyhalothrin have reported to be effective, but are toxic to people, destroy natural enemies and contaminate the environment. Botanical pesticides are the promising alternatives. This review paper explains toxicity, persistence and mode of actions of active ingredients of botanical pesticides. Rotenone from T. vogelii has the oral lethal dose (LD50) of 132 - 1500 mg/kg to mammals. It delays the electron transport chain in mitochondria of the insects and limits the cellular energy production. Azadirachtin is antifeedant and growth disruptor of insects. It has low toxicity to mammals. The oral LD50 in mammals is greater than 3540 mg/kg. Azadirachtin displays strong effects on chemoreceptors of the insects. Pyrethrins are axonic poisons and have repellent effects to insects. It is less toxic to mammals with the LD50 of about 1500 mg/Kg. It attacks the nervous systems of insects. Sesquiterpene lactones from T. diversifolia, Pentacyclic triterpenoids from Lantana camara, Vernodalin, Vernodalol and Epivernodalol from V. amygdalina have repellent and feeding deterrents chemicals which discourage the insects from feeding the crop. Most active ingredients of botanical pesticides have short life span in the environment.
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