MODELING INFLORESCENCE DEVELOPMENT OF TH AFRICAN VIOLET (SAINTPAULIA-IONANTHA WENDL)

The effects of temperature and daily-integrated photosynthetic photon flux (PPF(DI)) on African violet (Saintpaulia ionantha Wendl.) flower initiation and development were quantified to provide the basis for an inflorescence development model. The percentage of leaf axis in which an inflorescence initiated and continued development increased as the PPF(DI) increased from 1 to 4 mol.m-2.day-1, while the rate of inflor escence development was a function of the average daily temperature (A DT). The appearance of a visible flower bud (VB) in a leaf axil was re lated to the growth of the subtending leaf blade. A polynomial model b ased on ADT and PPF(DI) was used to describe leaf blade length at visi ble bud (LBL(VB)). A nonlinear model was used to describe the influenc e of ADT on leaf expansion rate (LER). Inflorescence appearance in the leaf axil was predicted by measuring LBL and estimating the time for the leaf blade to develop to the length required for VB. A phasic-deve lopment scale was developed to quantify inflorescence development. Day s required for an inflorescence to develop from VB to first open flowe r was described as a function of ADT and either inflorescence height o r inflorescence development stage (IDS). Days from leaf emergence to f irst open flower for the inflorescence initiated in that leaf axil dec reased from 86 to 55 as ADT increased from 18 to 26C.