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Apeldoorn, Netherlands

Haileselassie B.,Tigray Agricultural Research Institute | Haileselassie B.,Wageningen University | Stomph T.-J.,Center for Crop Systems Analysis | Hoffland E.,Wageningen University
Soil Science and Plant Nutrition

Teff (Eragrostis tef (Zucc.) Trotter) is a major food crop in Ethiopia and Eritrea. It is well adapted to Vertisols. Yields are low (around 1000 kg ha -1) despite fertilization with urea and diammonium phosphate. The objectives of this study were to understand farmers' perception on teff production constraints and to evaluate on-farm yield response of teff to zinc (Zn) fertilization. We conducted a farm survey and a participatory fertilization experiment in three teff-based sites (peasant associations) on Vertisols in the mid highland and lowland agroecological zones in Ethiopia. Per site 10 farmers participated in the survey and on-farm experiment. Poor soil fertility in the mid highland and moisture deficit in the lowland agroecological zones were mentioned by farmers as major teff production constraints, respectively. On-farm application of Zn fertilizer at a rate of 8 kg Zn ha -1 increased teff grain and straw yields by 14% and 15% on average, respectively, which could be economically profitable. Not all plots showed a positive response, however, indicating the necessity for enhanced insight in indicators for soil Zn bioavailability as a yield-limiting factor. Our study indicates the importance of Zn in teff production on Vertisols. We propose further research on management options to prepare for effective interventions based on the farm survey and on-farm experiment. © 2011 Japanese Society of Soil Science and Plant Nutrition. Source

Mafakheri A.,University of Kurdistan | Siosemardeh A.,University of Kurdistan | Bahramnejad B.,University of Kurdistan | Struik P.C.,Center for Crop Systems Analysis | Sohrabi E.,University of Kurdistan
Australian Journal of Crop Science

Drought stress is one of the major abiotic stresses in agriculture worldwide. This study was carried out to investigate the effect of drought stress on proline content, chlorophyll content, photosynthesis and transpiration, stomatal conductance and yield characteristics in three fgave the highest yield whereas the drought sensitive variety 'Pirouz' gave the lowest yield. Drought was carried out in a randomized complete block design with three replications. Treatments included control (no drought), drought stress imposed during the vegetative phase, drought stress imposed during anthesis and drought stress during the vegetative phase and during anthesis. All physiological parameters were affected by drought stress. Drought stress imposed during vegetative growth or anthesis significantly decreased chlorophyll a, chlorophyll b and total chlorophyll content. Proline accumulation was higher in 'ILC482' than in 'Pirouz' both under control and drought stress conditions. Photosynthesis, transpiration, stomatal conductance and yield were higher but sub-stomatal CO2 concentration was lower under drought stress conditions than under control conditions. The results showed that mesophyll resistance is the basic determinate of rate of phototosynthesis under drought stress conditions. Under drought conditions the drought tolerant variety 'Bivaniej' gave the highest yield whereas the drought sensitive variety 'Pirouz' gave the lowest yield. Drought stress at anthesis phase reduced seed yield more severe than that on vegetative stage. Source

Agency: Narcis | Branch: Project | Program: Completed | Phase: Social Sciences | Award Amount: | Year: 2007


Yan J.,China Agricultural University | Yan J.,Center for Crop Systems Analysis | Yu J.,China Agricultural University | Tao G.C.,China Agricultural University | And 4 more authors.
Field Crops Research

Water shortage in the Huai River Basin prompts farmers to adopt water-saving technologies such as direct-seeded nonflooded or aerobic rice. Different cultivation practices impact on tiller growth and development. Improved insight into tiller dynamics is needed to increase yield in these production systems. We conducted field experiments with four direct-seeded rice varieties under flooded and nonflooded conditions in Mengcheng county, Anhui province, in 2005-2006. The soil water content in the nonflooded treatment varied between saturation and field capacity. Yields in nonflooded soil ranged from 3.6 to 4.7 t ha-1, and did not differ significantly from yields in flooded soil that ranged from 3.6 to 5.1 t ha-1. Variety had a significant effect on biomass, yield, panicle number, spikelet number, grain weight, and grain filling percentage. Panicle number was the main factor limiting yield, resulting from a low tiller emergence frequency and a low fraction of productive tillers in both the flooded and the nonflooded soils. On average, the panicle number was 159-232 m-2, including 34-167 productive tillers per m2 for all the varieties under the two water regimes. The contribution of productive tillers to yield varied between 7% and 47%. There were two peaks of tillers that contributed to yield, one at the low (4th or 5th) and one at the high (10th or 11th) phytomer orders. Frequencies of tiller emergence at most phytomer orders were higher in the flooded soil than in the nonflooded soil. There were no significant differences in frequencies of productive tiller emergence and contributions to yield from tillers between the soil water regimes for three of the four tested varieties. To increase yield in direct-seeded nonflooded rice production systems, both the tiller emergence frequency and the fraction of productive tillers should increase through breeding, improved crop management, or a combination. © 2010 Elsevier B.V. All rights reserved. Source

Okello R.C.O.,Greenhouse Horticulture | Okello R.C.O.,Horticulture and Product Physiology Group | Okello R.C.O.,Center for Crop Systems Analysis | de Visser P.H.B.,Greenhouse Horticulture | And 4 more authors.
Environmental and Experimental Botany

Cell division, endoreduplication and cell expansion are key processes for plant growth and development. Light is the main source of energy for plants and as such has a strong effect on plant growth and development. Insight into the role of light in cellular processes is important for our understanding of plant responses to light. Recent advances in artificial plant lighting, cell imaging techniques and molecular biology have provided opportunities to study light responses of plants at the cell and gene level. Regulatory networks for cellular processes have also been unravelled and many transcription factors identified. In this review, we highlight key transcription factors and photoreceptors involved in the regulation of cell division, endoreduplication and cell expansion by light. We suggest that light responses result from either degradation of transcription factors or inhibitory competition between transcription factors for promoter regions of target genes. We also suggest that light stimulates cell division irrespective of the organ under consideration, while endoreduplication and cell expansion responses to light vary from organ to organ. © 2015 Elsevier B.V. Source

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