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Papers by David Elphinstone
The Journal of Agricultural Science, 1988
ABSTRACT Experiments were conducted in 1986 and 1987 to determine the influences of plant raising... more ABSTRACT Experiments were conducted in 1986 and 1987 to determine the influences of plant raising temperature, transplant age, N top-dressing and irrigation regime on the curd initiation and maturity characteristics of the cauliflower variety White Fox. The prime objective of this work was to determine whether changes in crop production practice had an influence on the period between curd initiation and maturity, in order to aid the development of techniques predicting when curds will reach a specific size.The duration of the period from curd initiation to curd maturity was not significantly affected by any treatment in either year and treatment effects on curd size at maturity were of no practical importance provided that the recommended level of N top-dressing was achieved. It is therefore concluded that changes in production practices within the normal commercial range are unlikely to have any significant practical effect on the use of techniques to predict the timing of crop maturity.There were large differences between the experiments in the mean number of leaves formed at curd initiation, which ranged from 22·0 to 36·7. In order to interpret these data a relative vernalization stimulus was calculated from 12 leaves onwards. It had a maximum rate of vernalization between 5 and 17 °C and a reduced rate at lower and higher temperatures and adequately accounted for the differences in the number of leaves at curd initiation.
Acta Horticulturae, 2013
Nurseries use irrigation for the production of high quality containerised trees. Future climate s... more Nurseries use irrigation for the production of high quality containerised trees. Future climate scenarios suggest that water resources for irrigation are likely to become increasingly scarce in many regions. A survey of the major UK nurseries producing amenity trees, revealed significant opportunities to enhance current irrigation practices by adopting already accepted irrigation strategies. Novel irrigation techniques such as deficit irrigation (DI), which provides less irrigation than plant potential evapotranspiration and partial rootzone drying (PRD) which deliberately seeks to impose soil moisture heterogeneity within the soil volume, have been used in various plant production systems to improve water-use-efficiency (WUE). Irrigation was automatically scheduled using dielectric soil moisture sensors to maintain volumetric soil moisture contents between 30-40% and 20-30% in two different treatments. Within each of these treatments, two alternative water distribution techniques were applied; full water distribution (WW) which ensures the entire soil volume is watered evenly; and an alternate partial rootzone drying (PRD-A) which irrigates half of the soil volume (by halving the number of drippers in each container) whilst allowing the other half to dry. After 26 days of treatment, gas exchange data revealed that the leaf-level WUE of the trees had significantly increased under the PRD-A treatment. By day 47 significant reductions in net photosynthetic assimilation and stomatal conductance were observed in the PRD-A treatment. Any deleterious effects on leaf gas exchange were reversed within 7 days by returning to full irrigation (30-40% WW). These data may be used to help develop more sustainable approaches to irrigation and the management of water resources. DI may prove an important strategy for increasing the resilience of tree and woody ornamental nurseries as competition for water resources becomes more acute.
Acta Horticulturae, 2011
... inoculation technique (Belimov et al., 2009): that of incorporating a rhizobacterial suspensi... more ... inoculation technique (Belimov et al., 2009): that of incorporating a rhizobacterial suspension into ... of spring rape to inoculation with plant growth-promoting rhizobacteria containing 1 ... in various agronomic crops by the plant growth promoting rhizobacterium Pseudomonas putida ...
Journal of experimental botany, Jan 4, 2015
To meet future requirements for food production, sustainable intensive agricultural systems need ... more To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6-6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3-6.7, reduced stomatal conductance (g s) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16-24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g s: both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchang...
Functional Plant Biology, 2014
ABSTRACT To test the hypothesis that root growth at depth is a key trait explaining some genotypi... more ABSTRACT To test the hypothesis that root growth at depth is a key trait explaining some genotypic differences in drought tolerance in potato (Solanum tuberosum L.), two varieties (Horizon and Maris Piper) differing in drought tolerance were subjected to different irrigation regimes in pots in a glasshouse and in the field under a polytunnel. In the glasshouse, both cultivars showed similar gas exchange, leaf water potential, leaf xylem ABA concentration and shoot biomass independently of whether plants were grown under well watered or water deficit conditions. Under well watered conditions, root growth was three-fold higher in Horizon compared with Maris Piper, 3 weeks after emergence. Water deficit reduced this difference. In the polytunnel, applying 60% or less irrigation volume compared with full irrigation significantly decreased tuber yield in Maris Piper but not in Horizon. This was coincident with the higher root density of Horizon in deep soil layers (>40 cm), where water content was stable. The results suggest that early vigorous root proliferation may be a useful selection trait for maintaining yield of potato under restricted irrigation or rainfall, because it rapidly secures access to water stored in deep soil layers. Although selecting for vigorous root growth may assist phenotyping screening for drought tolerance, these varieties may require particular environmental or cultural conditions to express root vigour, such as sufficiently deep soils or sufficient water shortly after emergence.
The arboriculture industry relies heavily on fossil fuel-powered equipment to maintain trees in u... more The arboriculture industry relies heavily on fossil fuel-powered equipment to maintain trees in urban areas; removing carbon sinks (trees) and emitting carbon dioxide (CO2) during management practices. It has been suggested that the arboriculture industry may make a disproportionately large contribution to greenhouse gas (GHG) emissions. The aim of this study was to identify the contribution of arboriculture to GHG emissions and provide recommendations for reduction. A case study of a tree surgery company (Down to Earth Trees Ltd) was used to assess indicative industry emissions. Direct emissions from sources owned or controlled by the company were 101.2 t of CO2e per year, with 5.2 t of CO2e per year of indirect emissions from energy use and 98.9 t of CO2e per year of indirect emissions from sources owned or controlled by other organisations. Results suggested that the arboriculture industry releases seven times more CO2e emissions per year than other similar-sized industries in the service sector. This was mainly attributed to the use of machinery and heavy-duty vehicles and removal of carbon storing biomass. Changing current practices could reduce GHG emissions from arboriculture by between 12% and 18%. Furthermore, by providing a renewable feedstock for generation of electricity, it is suggested that the arboriculture industry may achieve carbon positive status.
The Journal of Agricultural Science, 1988
ABSTRACT Experiments were conducted in 1986 and 1987 to determine the influences of plant raising... more ABSTRACT Experiments were conducted in 1986 and 1987 to determine the influences of plant raising temperature, transplant age, N top-dressing and irrigation regime on the curd initiation and maturity characteristics of the cauliflower variety White Fox. The prime objective of this work was to determine whether changes in crop production practice had an influence on the period between curd initiation and maturity, in order to aid the development of techniques predicting when curds will reach a specific size.The duration of the period from curd initiation to curd maturity was not significantly affected by any treatment in either year and treatment effects on curd size at maturity were of no practical importance provided that the recommended level of N top-dressing was achieved. It is therefore concluded that changes in production practices within the normal commercial range are unlikely to have any significant practical effect on the use of techniques to predict the timing of crop maturity.There were large differences between the experiments in the mean number of leaves formed at curd initiation, which ranged from 22·0 to 36·7. In order to interpret these data a relative vernalization stimulus was calculated from 12 leaves onwards. It had a maximum rate of vernalization between 5 and 17 °C and a reduced rate at lower and higher temperatures and adequately accounted for the differences in the number of leaves at curd initiation.
Acta Horticulturae, 2013
Nurseries use irrigation for the production of high quality containerised trees. Future climate s... more Nurseries use irrigation for the production of high quality containerised trees. Future climate scenarios suggest that water resources for irrigation are likely to become increasingly scarce in many regions. A survey of the major UK nurseries producing amenity trees, revealed significant opportunities to enhance current irrigation practices by adopting already accepted irrigation strategies. Novel irrigation techniques such as deficit irrigation (DI), which provides less irrigation than plant potential evapotranspiration and partial rootzone drying (PRD) which deliberately seeks to impose soil moisture heterogeneity within the soil volume, have been used in various plant production systems to improve water-use-efficiency (WUE). Irrigation was automatically scheduled using dielectric soil moisture sensors to maintain volumetric soil moisture contents between 30-40% and 20-30% in two different treatments. Within each of these treatments, two alternative water distribution techniques were applied; full water distribution (WW) which ensures the entire soil volume is watered evenly; and an alternate partial rootzone drying (PRD-A) which irrigates half of the soil volume (by halving the number of drippers in each container) whilst allowing the other half to dry. After 26 days of treatment, gas exchange data revealed that the leaf-level WUE of the trees had significantly increased under the PRD-A treatment. By day 47 significant reductions in net photosynthetic assimilation and stomatal conductance were observed in the PRD-A treatment. Any deleterious effects on leaf gas exchange were reversed within 7 days by returning to full irrigation (30-40% WW). These data may be used to help develop more sustainable approaches to irrigation and the management of water resources. DI may prove an important strategy for increasing the resilience of tree and woody ornamental nurseries as competition for water resources becomes more acute.
Acta Horticulturae, 2011
... inoculation technique (Belimov et al., 2009): that of incorporating a rhizobacterial suspensi... more ... inoculation technique (Belimov et al., 2009): that of incorporating a rhizobacterial suspension into ... of spring rape to inoculation with plant growth-promoting rhizobacteria containing 1 ... in various agronomic crops by the plant growth promoting rhizobacterium Pseudomonas putida ...
Journal of experimental botany, Jan 4, 2015
To meet future requirements for food production, sustainable intensive agricultural systems need ... more To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6-6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3-6.7, reduced stomatal conductance (g s) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16-24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g s: both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchang...
Functional Plant Biology, 2014
ABSTRACT To test the hypothesis that root growth at depth is a key trait explaining some genotypi... more ABSTRACT To test the hypothesis that root growth at depth is a key trait explaining some genotypic differences in drought tolerance in potato (Solanum tuberosum L.), two varieties (Horizon and Maris Piper) differing in drought tolerance were subjected to different irrigation regimes in pots in a glasshouse and in the field under a polytunnel. In the glasshouse, both cultivars showed similar gas exchange, leaf water potential, leaf xylem ABA concentration and shoot biomass independently of whether plants were grown under well watered or water deficit conditions. Under well watered conditions, root growth was three-fold higher in Horizon compared with Maris Piper, 3 weeks after emergence. Water deficit reduced this difference. In the polytunnel, applying 60% or less irrigation volume compared with full irrigation significantly decreased tuber yield in Maris Piper but not in Horizon. This was coincident with the higher root density of Horizon in deep soil layers (>40 cm), where water content was stable. The results suggest that early vigorous root proliferation may be a useful selection trait for maintaining yield of potato under restricted irrigation or rainfall, because it rapidly secures access to water stored in deep soil layers. Although selecting for vigorous root growth may assist phenotyping screening for drought tolerance, these varieties may require particular environmental or cultural conditions to express root vigour, such as sufficiently deep soils or sufficient water shortly after emergence.
The arboriculture industry relies heavily on fossil fuel-powered equipment to maintain trees in u... more The arboriculture industry relies heavily on fossil fuel-powered equipment to maintain trees in urban areas; removing carbon sinks (trees) and emitting carbon dioxide (CO2) during management practices. It has been suggested that the arboriculture industry may make a disproportionately large contribution to greenhouse gas (GHG) emissions. The aim of this study was to identify the contribution of arboriculture to GHG emissions and provide recommendations for reduction. A case study of a tree surgery company (Down to Earth Trees Ltd) was used to assess indicative industry emissions. Direct emissions from sources owned or controlled by the company were 101.2 t of CO2e per year, with 5.2 t of CO2e per year of indirect emissions from energy use and 98.9 t of CO2e per year of indirect emissions from sources owned or controlled by other organisations. Results suggested that the arboriculture industry releases seven times more CO2e emissions per year than other similar-sized industries in the service sector. This was mainly attributed to the use of machinery and heavy-duty vehicles and removal of carbon storing biomass. Changing current practices could reduce GHG emissions from arboriculture by between 12% and 18%. Furthermore, by providing a renewable feedstock for generation of electricity, it is suggested that the arboriculture industry may achieve carbon positive status.