title: Modelling temperature, photoperiod and vernalization responses of Brunonia australis (Goodeniaceae) and Calandrinia sp. (Portulacaceae) to predict flowering time.
abstract: OBJECTIVE
  Crop models for herbaceous ornamental species typically include functions for temperature and photoperiod responses, but very few incorporate vernalization, which is a requirement of many traditional crops. This study investigated the development of floriculture crop models, which describe temperature responses, plus photoperiod or vernalization requirements, using Australian native ephemerals Brunonia australis and Calandrinia sp.
  
  
  METHODS
  A novel approach involved the use of a field crop modelling tool, DEVEL2. This optimization program estimates the parameters of selected functions within the development rate models using an iterative process that minimizes sum of squares residual between estimated and observed days for the phenological event. Parameter profiling and jack-knifing are included in DEVEL2 to remove bias from parameter estimates and introduce rigour into the parameter selection process.
  
  
  RESULTS
  Development rate of B. australis from planting to first visible floral bud (VFB) was predicted using a multiplicative approach with a curvilinear function to describe temperature responses and a broken linear function to explain photoperiod responses. A similar model was used to describe the development rate of Calandrinia sp., except the photoperiod function was replaced with an exponential vernalization function, which explained a facultative cold requirement and included a coefficient for determining the vernalization ceiling temperature. Temperature was the main environmental factor influencing development rate for VFB to anthesis of both species and was predicted using a linear model.
  
  
  CONCLUSIONS
  The phenology models for B. australis and Calandrinia sp. described development rate from planting to VFB and from VFB to anthesis in response to temperature and photoperiod or vernalization and may assist modelling efforts of other herbaceous ornamental plants. In addition to crop management, the vernalization function could be used to identify plant communities most at risk from predicted increases in temperature due to global warming.
authors: The University of Queensland, School of Agriculture and Food Sciences, Gatton, Qld 4343, Australia. robyn.cave@uqconnect.edu.au
authors: Robyn L
authors: RL
authors: Cave
authors: Graeme L
authors: GL
authors: Hammer
authors: Greg
authors: G
authors: McLean
authors: Colin J
authors: CJ
authors: Birch
authors: John E
authors: JE
authors: Erwin
authors: Margaret E
authors: ME
authors: Johnston
mesh_terms: D035264:Flowers / Q000254:growth & development*; D016014:Linear Models; D019684:Magnoliopsida / Q000502:physiology*; D008954:Models, Biological; D017440:Photoperiod; D029622:Portulacaceae / Q000502:physiology; D013696:Temperature; D013997:Time Factors
references: Ann Bot. 2008 Oct;102(4):561-9
references: 18628262
references: Ann Bot. 2011 Jul;108(1):215-20
references: 21586530
references: New Phytol. 2012 May;194(3):654-665
references: 22352314