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1

Electronic Resource

Organic residues affect phosphorus availability and maize yields in a Nitisol of western Kenya (2000)

Nziguheba, G. ; Merckx, R. ; Palm, C. A. ; [et al.]

Springer

Biology and fertility of soils 32 (2000), S. 328-339

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ISSN: 1432-0789

Keywords: Key words Biomass transfer ; Maize ; Phosphorus ; Resin extractable phosphorus ; Triple superphosphate

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The effects of organic residues and inorganic fertilizers on P availability and maize yield were compared in a Nitisol of western Kenya. Leaf biomass of Calliandra calothyrsus, Senna spectabilis, Croton megalocarpus, Lantana camara, Sesbania sesban, and Tithonia diversifolia were incorporated into the soil at 5 Mg ha–1 for six consecutive seasons in 3 years and responses compared with those following the application of 120 kg N ha–1, 0 kg P ha–1 (0P); 120 kg N ha–1, 10 kg P ha–1; and 120 kg N ha–1 25 kg P ha–1 as urea and triple superphosphate (TSP); K was supplied in all treatments. Addition of Tithonia, Lantana and Croton increased soil resin-extractable P over that of fertilizer-amended soil throughout the first crop, but the amounts in the former treatments became similar to those for soils amended with inorganic fertilizers for subsequent crops. Addition of Sesbania, Calliandra and Senna had a similar effect on resin P as inorganic fertilizers. Total maize yields after six seasons were tripled by the application of Tithonia compared to 0P, and were higher than those of the Calliandra, Senna, Sesbania and Lantana treatments, and similar only to that of the Croton treatment. P recovered in the above-ground biomass and resin P, immediately after the implementation of the treatments, was higher in the Senna, Sesbania, Croton, Lantana and Tithonia (35–77%) treatments than in the inorganic fertilizer treatments (21–27%). The P content of organic residues, and the soluble C:total P ratio, were the main residue parameters predicting soil P availability and maize yield. All organic residues used in this study can replace inorganic fertilizers for the enhancement of P availability and maize production, while an additional benefit could be obtained from the use of Croton, Lantana and Tithonia.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003740000256

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2

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Insect pest problems in tropical agroforestry systems: Contributory factors and strategies for management (2000)

Rao, M. R. ; Singh, M. P. ; Day, R.

Springer

Agroforestry systems 50 (2000), S. 243-277

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ISSN: 1572-9680

Keywords: biomass transfer ; insect pests ; integrated pest management ; natural enemies ; sequential systems ; simultaneous systems

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006421701772

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Insect pests and beneficial arthropods population under different hedgerow intercropping systems in semiarid Kenya (2000)

Girma, H. ; Rao, M. R. ; Sithanantham, S.

Springer

Agroforestry systems 50 (2000), S. 279-292

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ISSN: 1572-9680

Keywords: alley cropping ; parasitoids ; predators

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Exploiting the principles of biological control of crop pests is an important management strategy for the resource-poor smallholder farmers of the tropics. The effects of nine hedgerow species on the abundance of major insect pests of beans and maize, and predatory/parasitic-arthropods were monitored over two cropping seasons and the intervening dry period. The tree/shrub species evaluated were Gliricidia sepium, Grevillea robusta, Senna siamea, Senna spectabilis, Flemingea congesta, Croton megalocarpus, Morus alba, Calliandra calothyrsus and Lantana camara. Arthropod abundance was monitored through counts of infested plants and using yellow pan and pitfall traps. Beanfly (Ophiomyia spp.) infestation was significantly higher in the presence of hedgerows (35%) than in their absence (25%). Hedgerows did not influence aphid (Aphis fabae) infestation of beans. In contrast, maize associated with hedgerows experienced significantly lower stalk borer (Busseola fusca and Chilo spp.) and aphid (Rhophalosiphum maidis) infestations than pure maize, the margin of difference being 13% and 11% respectively for the two pests. Ladybird beetles closely followed their prey, aphids, with significantly higher catches in sole cropped-plots than in hedgerow-plots and away from hedgerows. Activity of wasps was significantly greater close to hedgerows than away from them. Spider catches during maize season were 77% greater in the presence of hedgerows than in their absence, but catches during other seasons were similar between the two cropping systems. Differences among hedgerow species were not significant for most of the arthropods monitored, except that beanfly infestation was greater with Gliricidia hedgerows. The study indicates that the effect of hedgerows on pest infestations of crops and their role as refugia for predators cannot be generalized but depends on the specific arthropods.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006447813882

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4

Electronic Resource

Heterosis in growth and photosynthetic rate in hybrids of cotton (1981)

Bhatt, J. G. ; Rao, M. R. K.

Springer

Euphytica 30 (1981), S. 129-133

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ISSN: 1573-5060

Keywords: Gossypium hirsutum ; Gossypium barbadense ; cotton ; interspecific hybrids ; heterosis ; photosynthesis

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary The intraspecific (Gossipium hirsutum) and interspecific (G. hirsutum x G. barbadense) F1 hybrids of cotton were found to exhibit a high degree of heterosis in the production of fruiting branches, number of bolls (fruits), yield of seed cotton and photosynthetic rates over the parent plants. The developing bolls of the hybrids had significantly higher weights than their parents until the 20th day after anthesis. The patterns of leaf area development among interspecific hybrids differed when compared with the parent plants. The photosynthetic rates of the hybrids were comparable with those of maize and sorghum and much higher than the average rate reported so far for the cotton plant.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00033668

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A linear programming primer: from Fourier to Karmarkar (2019)

Chakraborty, Atlanta ; Chandru, Vijay ; Rao, M. R.

Springer

In: Annals of Operations Research. 2019; 287(2): 593-616. Published 2019 Mar 01. doi: 10.1007/s10479-019-03186-2.

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Publication Date: 2019-03-01

Print ISSN: 0254-5330

Electronic ISSN: 1572-9338

Topics: Mathematics , Economics

Published by Springer

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Mechanism of Wnt signaling induced down regulation of mrhl long non-coding RNA in mouse spermatogonial cells (2016)

Akhade, V. S., Dighe, S. N., Kataruka, S., Rao, M. R. S.

Oxford University Press

In: Nucleic Acids Research

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Publication Date: 2016-01-09

Description: Long non coding RNAs (lncRNAs) have emerged as important regulators of various biological processes. LncRNAs also behave as response elements or targets of signaling pathway(s) mediating cellular function. Wnt signaling is important in regulating mammalian spermatogenesis. Mrhl RNA negatively regulates canonical Wnt pathway and gets down regulated upon Wnt signaling activation in mouse spermatogonial cells. Also, mrhl RNA regulates expression of genes pertaining to Wnt pathway and spermatogenesis by binding to chromatin. In the present study, we delineate the detailed molecular mechanism of Wnt signaling induced mrhl RNA down regulation in mouse spermatogonial cells. Mrhl RNA has an independent transcription unit and our various experiments like Chromatin Immunoprecipitation (in cell line as well as mouse testis) and shRNA mediated down regulation convincingly show that β-catenin and TCF4, which are the key effector proteins of the Wnt signaling pathway are required for down regulation of mrhl RNA. We have identified Ctbp1 as the co-repressor and its occupancy on mrhl RNA promoter depends on both β-catenin and TCF4. Upon Wnt signaling activation, Ctbp1 mediated histone repression marks increase at the mrhl RNA promoter. We also demonstrate that Wnt signaling induced mrhl RNA down regulation results in an up regulation of various meiotic differentiation marker genes.

Print ISSN: 0305-1048

Electronic ISSN: 1362-4962

Topics: Biology