2.4. Data collection and analysis
Leaf number on the primary stem, which was based on the size of the stem and growing pattern of the plant, was recorded at the onset of treatments, and the most recently mature leaf was marked. Dates of first visible flower bud or inflorescence (VB) and first open flower were recorded. For plants in the Asteraceae family, flowering was considered to occur when the outermost row of ray flowers of an inflorescence was open. At flowering, VB number, leaf number on the stem with the first open flower, and plant height (from media surface to the apex of an inflorescence) were also recorded. Leaf number was not recorded for chrysanthemum grown under NI lighting treatments emitting R light because of the lack of a primary stem and inconsistent branching patterns. For each LDP in this report and petunia ‘Wave Purple Classic’ and ‘Wave Purple Improved’ (Meng and Runkle, 2015), a flowering promotion index was calculated for each NI lighting treatment by multiplying flowering percentage, reciprocal of flowering time, and minimum flowering time within cultivar (Runkle and Heins, 2003). Data were analyzed with SAS version 9.3 (SAS Institute, Inc., Cary, NC) mixed-model (PROC MIXED) and glimmix-model (PROC GLIMMIX) procedures, and pairwise comparisons between treatments were performed with Tukey's honest significant difference test (P = 0.05). Data between replications were pooled when the treatment by replication interaction was not significant or trends of treatment responses were consistent.