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Andrew F Smith - One of the best experts on this subject based on the ideXlab platform.
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fresh perspectives on the roles of arbuscular mycorrhizal fungi in Plant Nutrition and growth
Mycologia, 2012Co-Authors: Sally E Smith, Andrew F SmithAbstract:Recent research on arbuscular mycorrhizas has demonstrated that AM fungi play a significant role in Plant phosphorus (P) uptake, regardless of whether the Plant responds positively to colonization in terms of growth or P content. Here we focus particularly on implications of this finding for consideration of the balance between organic carbon (C) use by the fungi and P delivery (i.e. the C-P trade between the symbionts). Positive growth responses to arbuscular mycorrhizal (AM) colonization are attributed frequently to increased P uptake via the fungus, which results in relief of P deficiency and increased growth. Zero AM responses, compared with non-mycorrhizal (NM) Plants, have conventionally been attributed to failure of the fungi to deliver P to the Plants. Negative responses, combined with excessive C use, have been attributed to this failure. The fungi were viewed as parasites. Demonstration that the AM pathway of P uptake operates in such Plants indicates that direct P uptake by the roots is reduced and that the fungi are not parasites but mutualists because they deliver P as well as using C. We suggest that poor Plant growth is the result of P deficiency because AM fungi lower the amount of P taken up directly by roots but the AM uptake of P does compensate for the reduction. The implications of interplay between direct root uptake and AM fungal uptake of P also include increased tolerance of AM Plants to toxins such as arsenate and increased success when competing with NM Plants. Finally we discuss the new information on C-P trade in the context of control of the symbiosis by the fungus or the Plant, including new information (from NM Plants) on sugar transport and on the role of sucrose in the signaling network involved in responses of Plants to P deprivation.
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fresh perspectives on the roles of arbuscular mycorrhizal fungi in Plant Nutrition and growth
Mycologia, 2012Co-Authors: Sally E Smith, Andrew F SmithAbstract:Recent research on arbuscular mycorrhizas has demonstrated that AM fungi play a significant role in Plant phosphorus (P) uptake, regardless of whether the Plant responds positively to colonization in terms of growth or P content. Here we focus particularly on implications of this finding for consideration of the balance between organic carbon (C) use by the fungi and P delivery (i.e. the C–P trade between the symbionts). Positive growth responses to arbuscular mycorrhizal (AM) colonization are attributed frequently to increased P uptake via the fungus, which results in relief of P deficiency and increased growth. Zero AM responses, compared with non-mycorrhizal (NM) Plants, have conventionally been attributed to failure of the fungi to deliver P to the Plants. Negative responses, combined with excessive C use, have been attributed to this failure. The fungi were viewed as parasites. Demonstration that the AM pathway of P uptake operates in such Plants indicates that direct P uptake by the roots is reduced...
Sally E Smith - One of the best experts on this subject based on the ideXlab platform.
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fresh perspectives on the roles of arbuscular mycorrhizal fungi in Plant Nutrition and growth
Mycologia, 2012Co-Authors: Sally E Smith, Andrew F SmithAbstract:Recent research on arbuscular mycorrhizas has demonstrated that AM fungi play a significant role in Plant phosphorus (P) uptake, regardless of whether the Plant responds positively to colonization in terms of growth or P content. Here we focus particularly on implications of this finding for consideration of the balance between organic carbon (C) use by the fungi and P delivery (i.e. the C-P trade between the symbionts). Positive growth responses to arbuscular mycorrhizal (AM) colonization are attributed frequently to increased P uptake via the fungus, which results in relief of P deficiency and increased growth. Zero AM responses, compared with non-mycorrhizal (NM) Plants, have conventionally been attributed to failure of the fungi to deliver P to the Plants. Negative responses, combined with excessive C use, have been attributed to this failure. The fungi were viewed as parasites. Demonstration that the AM pathway of P uptake operates in such Plants indicates that direct P uptake by the roots is reduced and that the fungi are not parasites but mutualists because they deliver P as well as using C. We suggest that poor Plant growth is the result of P deficiency because AM fungi lower the amount of P taken up directly by roots but the AM uptake of P does compensate for the reduction. The implications of interplay between direct root uptake and AM fungal uptake of P also include increased tolerance of AM Plants to toxins such as arsenate and increased success when competing with NM Plants. Finally we discuss the new information on C-P trade in the context of control of the symbiosis by the fungus or the Plant, including new information (from NM Plants) on sugar transport and on the role of sucrose in the signaling network involved in responses of Plants to P deprivation.
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fresh perspectives on the roles of arbuscular mycorrhizal fungi in Plant Nutrition and growth
Mycologia, 2012Co-Authors: Sally E Smith, Andrew F SmithAbstract:Recent research on arbuscular mycorrhizas has demonstrated that AM fungi play a significant role in Plant phosphorus (P) uptake, regardless of whether the Plant responds positively to colonization in terms of growth or P content. Here we focus particularly on implications of this finding for consideration of the balance between organic carbon (C) use by the fungi and P delivery (i.e. the C–P trade between the symbionts). Positive growth responses to arbuscular mycorrhizal (AM) colonization are attributed frequently to increased P uptake via the fungus, which results in relief of P deficiency and increased growth. Zero AM responses, compared with non-mycorrhizal (NM) Plants, have conventionally been attributed to failure of the fungi to deliver P to the Plants. Negative responses, combined with excessive C use, have been attributed to this failure. The fungi were viewed as parasites. Demonstration that the AM pathway of P uptake operates in such Plants indicates that direct P uptake by the roots is reduced...
David A. C. Manning - One of the best experts on this subject based on the ideXlab platform.
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comparison of silicate minerals as sources of potassium for Plant Nutrition in sandy soil
European Journal of Soil Science, 2014Co-Authors: Kirsten Brandt, S M O Mohammed, Neil D Gray, M L White, David A. C. ManningAbstract:Summary Given the cost of conventional fertilizers and increasing demand as a result of increasing population growth, new sources of potassium (K) for Plant Nutrition need to be considered. Readily soluble nutrients are rapidly lost from well-drained soils, and so it is appropriate to consider silicate minerals that release K slowly during weathering. In this paper, we compare the availability to Plants grown in sandy soils of K from microcline (feldspar), biotite (mica) and nepheline syenite (nepheline + microcline) using leek (Allium ampeloprasum var. porrum L.) as a model Plant. Pot experiments were carried out under controlled environmental conditions using natural and artificial soil. The performance of the minerals was compared with treatment with KCl and a negative control (no K added). Plant shoot diameter was measured weekly to assess growth rates. After 10 weeks, Plant dry mass and soil and Plant contents of soluble K were measured to determine offtake; mineralogical changes in biotite-treated soils were assessed. Results for artificial and natural soil differed, reflecting differences in their mineralogy. With no added K, Plant growth ceased after 2 weeks. Growth rates were greatest for KCl, followed by biotite; linear growth continued for 5 weeks in the natural soil and for the entire 10 weeks in the artificial soil. Growth rates with nepheline syenite (natural soil) and microcline (both soils) did not differ significantly from the negative control, but for nepheline syenite, leek shoot K content was significantly greater, demonstrating availability of K from this source. X-ray diffraction analysis showed that biotite reacted to form vermiculite.
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Mineral sources of potassium for Plant Nutrition. A review.
Agronomy for Sustainable Development, 2010Co-Authors: David A. C. ManningAbstract:Recently published assessments of nutrient budgets on a national basis have shown that K deficits for developing countries are so substantial that a doubling of world production of potash fertilisers would be required to balance inputs and offtake, simply to meet demands in Africa alone. The price of potassium fertiliser raw materials has increased by a factor of 4 during 2007–2009, approaching $1000 per tonne in some markets. Thus an annual investment of the order of US$5600 million is required to replenish soil K stocks in Africa. In this context it is appropriate to review current knowledge of alternative sources of K, which is the seventh most abundant element in the Earth’s continental crust, present in feldspars and (much less commonly) feldspathoid minerals including nepheline and leucite. Theoretical considerations based on the experimental determination of mineral dissolution rates indicate that nepheline dissolves 100 times more quickly than potassium feldspar, and this suggests that nepheline-bearing rocks are more effective as sources of K for Plant growth than granitic rocks, even though these have higher K contents. Crop trials with silicate rocks and minerals as sources of K show increased K availability and uptake for nepheline-bearing rocks compared with granitic rocks. Under conditions where soils are rapidly leached (especially tropical soils such as oxisols that contain quartz, aluminium oxy-hydroxides and kaolinite), with low capacity to retain soluble nutrients, the use of potassium feldspar or crushed granite does give a yield response, although no greater than for conventional fertilisers. In other experiments with crushed ultramafic, basaltic and andesitic rocks improvements in crop yield are claimed, although this cannot be unambiguously related to the mineralogical or chemical composition of the rock used. In conclusion, the present high cost of conventional potassium fertilisers justifies further investigation of potassium silicate minerals and their host rocks (which in some cases include basic rocks, such as basalt) as alternative sources of K, especially for systems with highly weathered soils that lack a significant cation exchange capacity. Such soils commonly occur in developing countries, and so this approach provides an opportunity to develop indigenous silicate rock sources of K as an alternative to sometimes prohibitively expensive commercial fertilisers.
Susan K John - One of the best experts on this subject based on the ideXlab platform.
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soil Plant Nutrition of sweet potato and minor tuber crops a review
Journal of Root Crops, 2013Co-Authors: Susan K JohnAbstract:Among the tropical tuber crops, sweet potato is the most nutritious in terms of macro and micronutrients contained in both the tubers and the green leaves. Owing to these good quality traits, it is valued as a secondary staple in many underdeveloped and developing countries viz ., China, Africa, South America, South East Asia, Oceania etc., Nutrient management is one of the important topics that is intensively researched as it directly contributes to higher productivity and produce quality. Research on soil-Plant Nutrition undertaken in different sweet potato growing countries, the various soil factors influencing yield as well as quality of tubers, nutrient requirement, crop response to nutrients, nutrient management strategies, index leaf, critical nutrient concentration, Nutritional disorders etc., are reviewed in this paper. Minor tuber crops like arrowroot, Chinese potato, yam bean etc., are also important from the nutraceutical point of view, but yet to be explored to unravel the potential of these crops for various medicinal uses. The available literature on minor tuber crops that indicate their positive response to manures and fertilizers are also discussed.
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soil Plant Nutrition of sweet potato and minor tuber crops a review
Journal of Root Crops, 2013Co-Authors: Susan K JohnAbstract:Among the tropical tuber crops, sweet potato is the most nutritious in terms of macro and micronutrients contained in both the tubers and the green leaves. Owing to these good quality traits, it is valued as a secondary staple in many underdeveloped and developing countries viz ., China, Africa, South America, South East Asia, Oceania etc., Nutrient management is one of the important topics that is intensively researched as it directly contributes to higher productivity and produce quality. Research on soil-Plant Nutrition undertaken in different sweet potato growing countries, the various soil factors influencing yield as well as quality of tubers, nutrient requirement, crop response to nutrients, nutrient management strategies, index leaf, critical nutrient concentration, Nutritional disorders etc., are reviewed in this paper. Minor tuber crops like arrowroot, Chinese potato, yam bean etc., are also important from the nutraceutical point of view, but yet to be explored to unravel the potential of these crops for various medicinal uses. The available literature on minor tuber crops that indicate their positive response to manures and fertilizers are also discussed.
Carlmagnus Larsson - One of the best experts on this subject based on the ideXlab platform.
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Plant Nutrition dry matter gain and partitioning at the whole Plant level
Journal of Experimental Botany, 1996Co-Authors: A J S Mcdonald, T Ericsson, Carlmagnus LarssonAbstract:Differential flows of photoassimilate result in patterns of dry matter distribution among Plant organs. The extent to which these patterns are dependent on the flux of different mineral nutrients entering the root and the extent to which the distribution of dry matter in the whole Plant is affected by differentials in nutrient (primarily nitrate) flux among parts of the root system is considered. It is concluded that patterns of dry matter distribution and Nutritional status may depend on how nutrient supply has been manipulated about the root. Where the flux density of nutrient has been decreased and has become limiting to Plant growth, two categories of response have been observed. In the case of N, P or S, limiting flux density results in a proportionately greater amount of Plant dry matter in roots than is found at higher flux densities. This contrasts with the case of limiting K, Mg or Mn supply, where proportionately less Plant dry matter is found in roots at lower nutrient flux densities than at higher flux densities. In the case of N, particular attention is paid as to how sink strength may be related to differences between root and leaf cells in their capacity for loosening and synthesis processes in the primary cell wall.
