Circadian Leaf Movements: Persistence in Bean Plants Grown in Continuous High-Intensity Light

ABSTRACTirregularities, which represent upward and downward movements of small amplitude with periods of less than 1 hr (11). These irregularities, which are observed consistently in all movement records, may result from environmental fluctuations that trigger these responses. Bunning et al. (3) reported that these short period movements can become rhythmic when an intense environmental fluctuation is imposed upon the plants.Environment has a profound effect on leaf movements, but its role in initiating and maintaining these movements is uncertain. Although previous investigations have been conducted under uniform light and temperature conditions, the control of other environmental factors has not been emphasized. Perhaps fluctuations of environmental factors such as C02, relative humidity, nutrition, or water availability initiate and maintain leaf movements. The procedures for growing plants described herein and the facilities at the Biotron at the University of Wisconsin provided an opportunity to study leaf movement responses in an environment with a minimum amount of fluctuation in relative humidity, CO2, water tension, and mineral nutrition within a carefully controlled temperature and light room. MATERIAILS AND METHODSThe adzuki bean, Phaseolus angularis Wight., was selected in preference to the kidney bean, Phaseolus vulgaris L., because it is smaller in size and the unifoliate leaves are flatter, which makes it more desirable for time lapse photography of the leaf movements. Growth of this bean species was studied to determine the levels of temperature, light, humidity, and nutrition that provide optimal development of the young plants.A system was developed to minimize fluctuations in environmental factors. The plants were grown from seed in cubical blocks (52 cm3) molded from acrylonitrile modified cellulose wood fiber, BR-8 (American Can Co.) and then saturated with quarter-strength Hoagland's nutrient solution (6). The exposed surfaces of the blocks were covered with black plastic to reduce water loss. By means of a siphon system, a constant liquid level was maintained at the base of the blocks by additions of distilled water to replace water lost by transpiration and evaporation. This provided a nonfluctuating moisture and nutrition level. The plants were grown in a 75-X 40-x 45-cm airtight Plexiglass chamber placed within a controlled environment room of the Biotron. The Plexiglass chamber protected the plants against CO2 and humidity fluctuations while individuals were in the room. Rubber glove inserts permitted adjustment of the plant orientation following emergence. Continuous light at 600 ft-c intensity was provided by warm white fluorescent lamps supplemented with tungsten lamps. The light was monitored continuously with a selenium light sensor which was calibrated with a Kahl light meter. A spectral distribution of radiant energy obtained with a spectroradiometer is shown in Figure 1. A temperature of 24 C within the chamber was maintained through tem-

Section: Materiails and Methodssupporting

confidence: 51%

“…The movement rhythms are present under constant light and temperature conditions (2,4,7). Under continuous light these rhythmic movements have been recorded for a period of 4 weeks (8). It is assumed that these circadian movements are endogenous to the plant and that the "internal oscillator" (2) is expressed without any environmental stimuli.…”

mentioning

confidence: 99%

Circadian Rhythm of Leaves of Phaseolus angularis Plants Grown in a Controlled Carbon Dioxide and Humidity Environment

Alford

Tibbitts

1970

“…Rhythmic activity was generally observed for at least 6 days and for as long as 9 days in some plants. This is in contrast to circadian rhythm activity which began immediately when the leaves unfolded and was observed for as long as 28 days (9).…”

Section: Resultsmentioning

confidence: 71%

Endogenous Short Period Rhythms in the Movements of Unifoliate Leaves of Phaseolus angularis Wight

Alford

Tibbitts

1971

ABSTRACTtaneously in young seedlings grown under controlled environmental conditions of temperature, light, CO2, and relative humidity (1). Circumnutational movements have been observed most commonly in specialized leaves called tendrils (7,11,12) in which the tendril tips follow a more or less regular ellipse as they move. Darwin and Darwin (7) also noted movements of this type in the true leaves of many plant species. The leaf tips of Phaseolus vulgaris circumnutate approximately once each hour (14).This investigation describes in detail the nature and particularly the rhythmicity of blade rotation during the growth and maturation of the unifoliate leaves of P. angularis. MATERIALS AND METHODSThe leaf movements were recorded by time lapse photography. Phaseolus angularis was considered desirable for this type of study because of its small, ovate unifoliate leaves and slow growth characteristics. The plants were grown under continuous light of 600 4 15 ft-c, a temperature of 24.0 + 0.5 C, a relative humidity of 84 ± 4%, and sealed in a Plexiglass chamber to provide controlled conditions of CO2, water availability, and mineral nutrition. Carbon dioxide exhaustion was avoided by metering a constant flow of air from a compressed air cylinder continuously into the chamber during the growth of the plants. The Plexiglass chamber was maintained in a room of the Biotron, a controlled environment facility of the University of Wisconsin. Entry into the Plexiglass chamber was required only at the start of photographic recording for orientation of seedlings and once 8 days after leaf unfolding to remove the apical meristem and trifoliate leaves. The details involved in environmental control and cultural practices were described in a previous publication (1). Plant response data were taken from leaves of four plants in two

“…Even though this study was initiated to learn more about circadian leaf movements such as those reported by Hamner (7), Hoshizaki (8), and Trouse (12), the shorter interval movements became more interesting. Because the short interval rhythms have been noted in Desmodium gyrans, beans (1, 2), cotton (6), and about 40 other types of plants (4), they are undoubtedly important physiologically.…”

Section: Discussionmentioning

confidence: 99%

Short Interval Leaf Movements of Cotton

Miller

1975

Gossypium hirsutumn L. cv. Lankart plants exhibited three different types of independent short interval leaf movements which were superimposed on the circadian movements. The different types were termed SIRV (short interval rhythmical vertical), SIHM (short interval horizontal movements), and SHAKE (short stroked SIRV). The 36-minute period SIRV movements occurred at higher moisture levels. The 176-minute period SIHM occurred at lower moisture levels and ceased as the stress increased. The SHAKE movements were initiated with further stresses. The SLEEP (circadian, diurnal) (1-3, 6, 9). The shorter cycle leaf movements are known to occur in several species of plants (4).In this study, evidence will be presented that the short interval leaf movements are separate and distinct from the circadian movements and that there are different types which occur at different moisture stresses. MATERIALS AND METHODSSeed of Gossypium hirsutum L. cv. Lankart were planted in 20-cm diameter plastic pots which contained a 50:50 mixture of peatmoss and perlite. The plants were grown in a greenhouse and were watered with the equivalent of 0.5 strength Hoagland's solution in tap water with periodic tap water flushing until they were at the 5 to 10 true-leaf stage. Routinely, the plants were transported into the laboratory in the afternoon and placed under the continuous illumination from a light bank containing six 40-w, 4-foot Gro-Lux F-40 lamps and two 200-w incandescent lights. The tops of the plants, depending on their height, were between 1 and 3 feet from the light bank and thus received between 3,000 and 15,000 ,uw/cm2 radiation which peaked at 660 nm. The temperatures were maintained between 29 40%. The plants were photographed with a 16-mm movie camera fitted with a time lapse drive and timers. After development, the sequences were projected directly on the chart paper of a recorder with the use of a special projector. The position of the tip of the leaf was marked as to its vertical components. In one case, the horizontal components were also graphed.Moisture Stress Series. For this series, the cotton seeds were planted in three pots each containing 650 g dry weight of peatmoss-perlite mixture. Another three pots were planted, each of which contained 3,000 g dry weight of Miller clay. Those in Miller clay were watered with distilled water only. At 12, 21, and 41 days after planting, respectively, one pot of the seedlings in the Miller clay containing two seedlings per pot was placed under continuous light at conditions previously described for about 2 weeks of photographic observation.The seedlings planted at different times in the peatmossperlite mixture were watered with 0.5 strength Hoagland's and were 20, 25, and 28 days from planting, respectively, at the time of initial photography. Each pot was placed on a scale so that weights could be observed and recorded. Only one of the pots was watered during the period of observation.At the end of the moisture stress sequences, the plants were pulled up, the potti...