Prediction of developmental events on Spathiphyllum floribundum Schott 'Petite' based on air thermal units

Container-grown flowering plants are produced for specific market dates; therefore, the ability to predict the time of flowering is essential. The dates of occurrence of "tiller development", unfolding of each leaf, occurrence of "visible spathe" for the principal shoot and the first tiller of Spathiphyllum floribundum 'Petite', were observed for 210 whole plants. Half-hourly averages of air temperatures and photosynthetic photon flux density (PPFD) were recorded. Temperature affected rate of tiller and flowering development, but the integrated PPFD did not. Two separated experiments were performed; the first was made to calculate predicting equations and the second for its validation. Thermal time methodology was used. The base temperature was found to be nearly 12°C. Thermal units were computed and found to be suitable for tracking most phases of S. floribundum 'Petite' crop development; they were 360.00 ′ 4.00; 185.00 ′ 25.50; 186.60 ′ 23.70; 1,512.30 ′ 225.60 and 1,132.00 ′ 36.00°C days for "first tiller development", "second tiller development", "third tiller development", "occurrence of visible first plant inflorescence" and "occurrence of visible first tiller inflorescence", respectively. Errors of prediction for all phases and occurrence of "unfolding of each leaf" were also calculated.