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dc.contributor.authorTeixeira, Edmar I.en
dc.contributor.authorMoot, Derrick J.en
dc.contributor.authorBrown, H. E.en
dc.date.accessioned2012-03-08T02:08:57Z
dc.date.issued2008en
dc.identifier.citationTeixiera, E. I., Moot, D. J., & Brown, H. E. (2008). Defoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) crops. European Journal of Agronomy, 28(2), 103-111.en
dc.identifier.issn1161-0301en
dc.identifier.urihttps://hdl.handle.net/10182/4327
dc.description.abstractRadiation use efficiency (RUE), and subsequent partitioning between shoots and roots were investigated for ‘Grasslands Kaituna’ lucerne crops grown in the cool temperate climate of Canterbury, New Zealand. Crops were grazed by sheep every 28 or 42 days and yielded 12 and 23 t DM/ha.year, respectively. The RUE for above ground shoots (RUEshoot) was 1.7-2.0 g DM/MJ of intercepted photosynthetically active radiation (PARᵢ) in spring but decreased systematically to ≤1.0 g DM/MJ PARᵢ in autumn. The RUE for total biomass, (RUEtotal) ranged from 1.3 to 3.1 g DM/MJ PARᵢ in response to air temperature and defoliation treatment. The lowest RUEtotal in mid summer for the treatment defoliated every 28 days was related to a 20% decline in the leaf photosynthetic capacity measured at 1000 μmol photons/m2.s (Pn1000) and at saturating light (Pmax). In turn, the reduction in Pn1000 was related to differences in specific leaf nitrogen (SLN), through changes in specific leaf weight (SLW) rather than the leaf N concentration of 4 to 6% DM. The fractional partitioning of DM to roots (proot) increased from near zero in winter/earlyspring to >0.45 in autumn, which explained the observed seasonality of RUEshoot. For the treatment defoliated each 42 days, proot increased linearly from ~0.05 to >0.45 as Pp increased from 10.5 to 16.5 h. In decreasing photoperiods proot averaged 0.45. There was a linear increase (R²=0.52) in proot with Tsoil/Tair but only in the treatment defoliated each 42 days. Agronomic treatments that result in sub optimal N reserves post grazing can be expected to produce conservative canopy characteristics but reduced photosynthetic capacity of the first 5 main stem leaves. Beyond this development stage, canopy expansion may be reduced with more conservative leaf N.en
dc.format.extent103-111en
dc.language.isoenen
dc.publisherElsevieren
dc.relationThe original publication is available from - Elsevieren
dc.rightsCopyright © 2008 Elsevier Ltd. All rights reserved.en
dc.subjectalfalfaen
dc.subjectcarbon and nitrogen partitioningen
dc.subjectlight use efficiencyen
dc.subjectphotosynthesisen
dc.subjectshoot to root ratioen
dc.subjectsimulation modellingen
dc.subjectlucerne cropsen
dc.subjectMedicago sativa L.en
dc.subjectshoot/root ratioen
dc.subjectroot reservesen
dc.subjectAgronomy & Agricultureen
dc.titleDefoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) cropsen
dc.typeJournal Article
lu.contributor.unitLincoln Universityen
lu.contributor.unitFaculty of Agriculture and Life Sciencesen
lu.contributor.unitDepartment of Agricultural Sciencesen
lu.contributor.unitResearch Management Officeen
lu.contributor.unit/LU/Research Management Office/2018 PBRF Staff groupen
lu.contributor.unitSoil, Plants and Ecological Sciencesen
lu.contributor.unit/LU/SPES/PLANTen
dc.subject.anzsrc070302 Agronomyen
dc.subject.anzsrc0703 Crop and Pasture Productionen
dc.relation.isPartOfEuropean Journal of Agronomyen
pubs.organisational-group/LU
pubs.organisational-group/LU/Agriculture and Life Sciences
pubs.organisational-group/LU/Agriculture and Life Sciences/AGSC
pubs.organisational-group/LU/Research Management Office
pubs.organisational-group/LU/Research Management Office/2018 PBRF Staff group
pubs.organisational-group/LU/SPES
pubs.organisational-group/LU/SPES/PLANT
pubs.publication-statusPublisheden
pubs.volume28en


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