5 research outputs found
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Effects of Irrigation Frequency and Nitrogen Fertilizer Rate on Water Stress, Nitrogen Uptake, and Plant Growth of Container-grown Rhododendron
The influence of irrigation frequency (same amount of water per day given at different times) and nitrogen (N) fertilizer rate on water stress [stomatal conductance (gs)], N uptake, and growth (biomass) of container-grown evergreen Rhododendron 'P.J.M. Compact' and 'English Roseum' and deciduous Rhododendron 'Gibraltar' was evaluated. Both N deficiency and high N rate increased water stress. Water stress was greatest in plants fertilized with the highest N rate and gs of plants grown with the higher N rates changed more in response to water deficits resulting from irrigation treatments and seasonal climatic changes. Watering plants more frequently decreased water stress of plants fertilized with higher N rates and altering irrigation frequency had little impact on alleviating water stress of N-deficient plants. Increasing irrigation frequency decreased N uptake efficiency (N uptake per gram N applied), increased N use efficiency (growth per gram N uptake) and altered biomass allocation with little influence on total plant biomass. Response of biomass allocation to N rates was similar among cultivars and response of biomass allocation to irrigation frequency varied among cultivars. Altering irrigation frequency changed either the availability of N in the growing substrate or the ability of roots to absorb N. Our results indicate that transitory increases in plant water stress can alter N uptake, N use, and plant form without detectable changes in total plant biomass.Keywords: P.J.M. compact,
Rhododendron 'Gibralter',
Rhododendron,
Nursery production,
Rhododendroon 'English Roseum',
Water use,
Nitrogen uptak
Inoculation with Ericoid Mycorrhizal Fungi Alters Root Colonization and Growth in Nursery Production of Blueberry Plants from Tissue Culture and Cuttings
Frequency and Intensity of Root Colonization by Ericoid Mycorrhizal Fungi in Nursery Production of Blueberry Plants
Cultural Variation and Mycorrhizal Status of Blueberry Plants in NW Oregon Commercial Production Fields
Genetic variation for root architecture, nutrient uptake and mycorrhizal colonisation in Medicago truncatula accessions
Sustainable agriculture strives for healthy, high yielding plants with minimal agronomic inputs. Genetic solutions to increase nutrient uptake are desirable because they provide ongoing improvements. To achieve this it is necessary to identify genes involved in uptake and translocation of nutrients. We selected Medicago truncatula L. as a model because of its: i) close genetic relationship to food legumes, ii) use as a pasture legume in southern Australia and iii) availability of mapping populations generated from genetically diverse accessions. We discovered statistically significant differences between eight accessions for: root architecture in growth pouches, % root colonisation with the arbuscular mycorrhizal (AM) fungus Glomus intraradices, and plant tissue concentration of most macro- and micronutrients. Mycorrhizal colonisation had a significant effect on P concentration in roots but not shoots, Mg concentration in both roots and shoots, and the concentration of various micronutrients in shoots including Fe, Ca, but not Zn. Comparison of micronutrient uptake between root and shoot tissues showed that some M. truncatula accessions were more efficient at mobilisation of nutrients from roots to shoots. We are now in a position to use existing mapping populations of M. truncatula to identify quantitative trait loci important for human health and sustainable agriculture.Carolyn J. Schultz, Leon V. Kochian and Maria J. Harriso