Determination of leaf area and leaf number of Calandiva® associated with the accumulation of degree-day

Calandiva® is an ornamental species that is gaining prominence in the market of potted flowers due to the attractiveness of its inflorescences. Since it has been cultivated recently, some aspects of its development are still unknown. The objective of this study was to verify a mathematical procedure that allows to describe the formation and development of Calandiva® leaves associated with the growing degree-days accumulation (GDD). Two experiments were conducted using cuttings of Kalanchoe blossfeldiana 'Bisset' (Calandiva® Pink) and K. blossfeldiana 'Latin Lover Rio' (Calandiva® Orange), planted and grown in plastic pots containing substrate and submitted to fertigation. The experimental design was complete randomized block with four replicates. Each useful plot consisted of three plants, totaling twelve plants per assessment. Every fourteen days, during 105 days, the leaf area was determined with the aid of a leaf area meter. Seven destructive assessments were performed in each experiment. Two models were developed describing the relationship between leaf growth and GDD accumulation in Calandiva®. Growth data obtained of the 'Bisset' cultivar were used to develop these models and the validation was performed using data of the 'Latin Lover Rio' cultivar. The models have been validated and are acceptable for use to correlate of leaf area and number of leaves with growing degree-day in Calandiva® plants.