Role of Light Quality, Photoperiod, and High-intensity Supplemental Lighting on Flowering of Alstroemeria ‘Regina’1

Abstract

Alstroemeria L. ‘Regina’ plants grown at 22°C did not flower, regardless of photoperiod treatments. If grown at 13°, plants flowered sooner under long photoperiod treatments than under natural days (ND). Incandescent (Inc) or red light treatments applied as a night interruption (NI) promoted earlier flowering than NI-far-red, ND, or short days (SD). Number of flowering shoots was unaffected by light quality. Plants grown under SD treatments produced the fewest flowering shoots. Flower production was related to early commencement and subsequent duration of the flowering span, as all plants ceased flowering on similar dates. When plants were rotated every 20, 30, or 40 days between SD and NI-Inc light treatments, the days to flower were delayed compared to plants grown continuously (nonrotated) under NI-Inc. Nevertheless, plants which were rotated between the various SD and NI-Inc light treatments flowered sooner than plants under continuous SD. Days to flower were reduced when plants were transferred monthly (December to June) from SD to either ND, 20 hr Inc, or 10 or 20 hr of high-intensity discharge (HID) lights. Flowering was hastened by 20 hr of HID lighting when compared to Inc during the months when the natural photoperiod was less than 12 hr, but had no influence when the 20-HID light treatment commenced after the natural photoperiod was greater than 12 hr. Maintaining plants under SD past January delayed the start of flowering, regardless of subsequent light treatments.

Relationship between Rhizome Temperatures and Shoot Temperatures for Floral Initiation and Cut Flower Production of Alstroemeria ‘Regina’

“…Although researchers have investigated the effect of alternating temperatures (10,15), constant low air temperatures (4,5,7,13,14,15), or high air temperatures (4,5,8,13,14) on growth and flowering of alstroemeria, no one yet has shown a definite relationship between controlled soil temperature and floral induction (Table 1) or soil/air temperature X photoperiod with flower induction and generative shoot production of Alstroemeria 'Regina' (Table 2). Lin (11) reported that circulating 10°C tap water in pipes 25 cm below the soil surface increased spring-summer production, and a 16-hr high-pressure sodium lighting regime reduced flowering.…”

“…The exact control mechanisms for Alstroemeria 'Regina' flower induction, initiation, and development are not clearly understood (4,5,6,7,8). Several workers have shown the influence of air temperature on generative alstroemeria shoot induction and subsequent shoot and flower development (3,5,6,7,9,10,14).…”

“…Light treatments (photoperiodic and photosynthetic) have been reported to hasten generative (flowering) shoot development of alstroemeria (4,8,10,12,14). Long days, either as a nightinterruption or as a day-continuation of 13-to 16-hr, depending on cultivar, accelerated flowering (4,8,10,12). Generative shoot development ceased during high temperature periods and failed to respond to any light treatment (3,4,6,7,8,9,10).…”

“…Long days, either as a nightinterruption or as a day-continuation of 13-to 16-hr, depending on cultivar, accelerated flowering (4,8,10,12). Generative shoot development ceased during high temperature periods and failed to respond to any light treatment (3,4,6,7,8,9,10).…”

The Effect of Soil Cooling and High Intensity Supplementary Lighting on Flowering of Alstroemeria ‘Regina’

“…In winter, only plants treated with the combination of soil cooling and HPS lighting produced flowers.Recent research on Alstroemeria (Lily-ofthe-Incas) flowering has been devoted to its earliness (3, 4). Early flowering increases the production span and thereby productivity, because all Alstroemeria plants cease flow ering at about the same time, regardless of previous photoperiod treatments (5).Temperature and light have been studied previously with regard to Alstroemeria flow ering (1,3,4,9). It has been suggested that Alstroemeria flowering involves a phasic mechanism in which thermophase precedes photophase (3).…”