Qualitative Short-day Plant Research Articles

Low-Intensity Blue Light Supplemented during Photoperiod in Controlled Environment Induces Flowering and Antioxidant Production in Kalanchoe.

Kalanchoe (Kalanchoe blossfeldiana) is a qualitative short-day plant with a high aesthetic value. When the night length is less than a specified cultivar-dependent critical value, however, it does not develop flowers. This study investigated the effects of low-intensity supplementary or night interrupting (NI) blue (B) light on the plant performance and flower induction in kalanchoe ‘Rudak’. During the photoperiod in a closed-type plant factory with day/night temperatures of 23 °C/18 °C, white (W) LEDs were utilized to produce a photosynthetic photon flux density (PPFD) of 300 μmol m−2 s−1, and B LEDs were used to give supplementary/NI light at a PPFD of 10 μmol m−2 s−1. The control plants were exposed to a 10-h short day (SD, positive control) or a 13-h long day (LD, negative control) treatment without any B light. The B light was used for 4 h either (1) to supplement the W LEDs at the end of the SD (SD + 4B) and LD (LD + 4B), or (2) to provide night interruption (NI) in the SD (SD + NI-4B) and LD (LD + NI-4B). The LD + 4B and LD + NI-4B significantly enhanced plant growth and development, followed by the SD + 4B and SD + NI-4B treatments. In addition, the photosynthesis, physiological parameters, and activity of antioxidant systems were improved in those treatments. Except in the LD and LD + NI-4B, all plants flowered. It is noteworthy that kalanchoe ‘Rudak’ flowered in the LD + 4B treatment and induced the greatest number of flowers, followed by SD + NI-4B and SD + 4B. Plants grown in the LD + 4B treatment had the highest expression levels of certain monitored genes related to flowering. The results indicate that a 4-h supplementation of B light during the photoperiod in both the SD and LD treatments increased flower bud formation, promoted flowering, and enhanced plant performance. Kalanchoe ‘Rudak’ flowered especially well in the LD + 4B, presenting a possibility of practically inducing flowering in long-day seasons with B light application.

How Supplementary or Night-Interrupting Low-Intensity Blue Light Affects the Flower Induction in Chrysanthemum, A Qualitative Short-Day Plant.

This research examined the effects of the supplementary or night-interrupting (NI) blue (B) light supplied at a low intensity on the flowering, gene expression, and morphogenesis of chrysanthemum, a qualitative short-day plant. White (W) light-emitting diodes (LEDs) were used to provide light with a photosynthetic photon flux density (PPFD) of 180 μmol·m−2·s−1 during the photoperiod to grow the plants in a plant factory. The control group was constructed with plants that were exposed to a 10-h short day (SD10) treatment without any blue light. The B light in this research was used for 4 h to either (1) extend the photoperiod for plants at the end of a 9-h short day (SD) treatment as the sole light source (SD9 + 4B), (2) provide night interruption (NI) to plants in the 13-h long-day (LD) treatment (LD13 + NI − 4B), (3) provide NI to plants in the 10-h SD treatment (SD10 + NI − 4B), or (4) supplement the W LEDs at the end of a 13-h LD treatment (LD13 + 4B). Blue LEDs were used to provide the supplementary/NI light at 10 μmol·m−2·s−1 PPFD. The LD13 + NI − 4B treatment resulted in the greatest plant height, followed by LD13 + 4B. Plants in all treatments flowered. It is noteworthy that despite the fact that chrysanthemum is a qualitative SD plant, chrysanthemum plants flowered when grown in the LD13 + 4B and LD13 + NI − 4B treatments. Plants grown in the LD13 + 4B had the greatest number of flowers. Plants grown in the LD13 + 4B treatment had the highest expression levels of the cryptochrome 1, phytochrome A, and phytochrome B genes. The results of this study indicate that a 4-h supplementation of B light during the photoperiod increases flower bud formation and promotes flowering, and presents a possibility as an alternative method to using blackout curtains in LD seasons to practically induce flowering. The B light application methods to induce flowering in SD plants requires further research.

Both the Quality and Positioning of the Night Interruption Light are Important for Flowering and Plant Extension Growth

Chrysanthemum (Dendranthema grandiflorum Kitamura), a qualitative short-day plant, does not produce flowers when the night length is shorter than a cultivar-dependent critical value. Flowering is effectively inhibited when the required uninterrupted night period is broken by short periods of exposure to night interruption lights (NILs). The effects of the quality and positioning of the NIL on the morphogenesis, flowering, and photoperiodic gene expressions of chrysanthemum were investigated. Blue (NI-B), red (NI-R), far-red (NI-Fr), and white (NI-W) light-emitting diodes (LEDs) at an intensity of 10 μmol m−2 s−1 photosynthetic photon flux density (PPFD) were used to interrupt the dark period or plants grown in a closed walk-in growth chamber at night for a total of 4 h. The NILs were positioned to illuminate either the shoot tip, youngest mature leaf (vigorously growing third leaf from the shoot tip), or old leaf (third leaf from the stem base). The NI-R on the shoot tip and all NI-Fr treatments increased the plant extension growth, to a similar height observed in plants in long-day (LD) treatments. Extension growth was generally suppressed for plants in the NI-B, and plant height was the smallest when NI-B was shed onto the old leaf. Plants in all NIL treatments except NI-Fr showed a negative correlation between the plant height and the age of the leaf (or tissue) exposed to the NIL. Flowering was observed for plants in all treatments except for NI-R shed onto the shoot tip. The transcriptional factor PHYA was slightly expressed in plants which showed a flowering response. However, the CRY1, PHYB, and TFL was not expressed to levels reported previously, and the reason for low expression of these genes in these plants may be due to a combined effect of these genes with other flowering promoting and/or inhibiting genes. These results suggest that both the NIL quality and the age of the leaf (or tissue) exposed to the NIL affect the morphogenesis, flowering, and expression of transcriptional factors. Moreover, the previously known effects of the NIL quality on the morphogenesis as well as the vegetative to reproductive phase transition of plants were the most pronounced when the NIL irradiated the shoot tip, and the least pronounced when the NIL was shed onto the old leaf. Therefore, it seems that not only the appropriate quality, but also the appropriate positioning of the NIL, is important for optimizing flowering and plant extension growth.

Night interruption light quality changes morphogenesis, flowering, and gene expression in Dendranthema grandiflorum

We investigated the effects of the quality of light used for interrupting the night period, termed the night interruption light (NIL), on morphogenesis, flowering, and the expression of photoperiodic genes in chrysanthemum (Dendranthema grandiflorum) cultivar ‘Gaya Yellow’, a qualitative short-day (SD) plant. Plants were raised in a closed-type plant factory under white (W) light-emitting diodes (LEDs) providing a light intensity of 180 μmol m−2 s−1 photosynthetic photon flux density, under a condition of long-day (LD, 16 h light/8 h dark), short-day (SD, 10 h light/14 h dark), or SD with a 4-h night interruption (NI) provided by 10 μmol m−2 s−1 PPF green (NI-G), blue (NI-B), red (NI-R), far-red (NI-Fr), or W (NI-W) LEDs. Plants grown in the LD condition were the tallest. The SD, NI-B, and NI-Fr conditions induced flowering. Phytochrome A (phyA) and cryptochrome 1 (cry1) were expressed at high levels in plants in NI-B, NI-Fr, and SD conditions. These results suggest that the NIL quality has significant implications on morphogenesis, flowering, and the expression of photoperiodic genes. Flowering was positively affected by the expression of phyA, cry1, and FLOWERING LOCUS T (FT), whereas it was negatively affected by the expression of phyB and anti-florigenic FT/TFL1 (AFT).

Effects of light quality on the flowering responses inKalanchoe blossfeldiana

Light is one of the most important environmental factors and has at least three aspects; intensity, photoperiod and quality. There are many studies of the influences of light intensity and the photoperiod on flowering responses. Those results led to the development of novel practical technology for the control of flowering. However, there are many still unexplained phenomena on the light quality. Kalanchoe (Kalanchoe blossfeldiana Poellniz.) is well known as a typical qualitative (obligate) short-day (SD) plant and it has been used as experimental material for the flowering response. Thus, the flowering responses of two cultivars of kalanchoe, 'Arena' and 'Cora', were studied under the following light regimes: SD under four different light emitting diodes (LEDs), white, blue, green and red; SD under natural light + light extension (LE; 7 h from midnight); SD under natural light + photoperiod extension (12 h; 6:00-18:00) with supplementary LED lighting (four colours as above). In the case of LE, the flowering was completely inhibited under each light quality. Under SD, the earliest flowering occurred under red light. Blue light considerably delayed flowering. In contrast, photoperiod extension (to the critical photoperiod for kalanchoe) with blue light caused a distinct flowering response but there was no flowering under supplementary red and green light. It is concluded that the flowering of kalanchoe is mainly controlled by red light. The direct flowering response to blue light was weak but blue light had a secondary or indirect effect.

Is Impatiens balsamina a qualitative short-day plant?

<em>Impatiens balsamina</em> which, in literature on the physiology of flowering, is assigned to qualitative short-day plants, flowers under Polish climatic conditions from June until September. It flowers, therefore. during the period of the longest day. The photoperiodic responses of <em>I. balsamina</em> plants raised from seeds obtained from botanical gardens located within the range of 23 -65° N. lat. were studied. The experiment revealed marked differences in the photoperiodic responses within the species. Qualitative short-day plants, quantitative short-day plants and day-neutral plants were found in the studied material. An evident correlation was found between the place of origin of the studied seeds and the photoperiodic sensitivity of the plants raised from them.

Chrysanthemum stunt viroid disturbs the photoperiodic response for flowering of chrysanthemum plants

Chrysanthemum ( Dendranthema grandiflorum Kitam.) is one of the qualitative short-day flowering plants. Therefore, the flowering of chrysanthemum can usually be controlled by photoperiod. However, it was noted that 'Piato' plants infected by the chrysanthemum stunt viroid (CSVd) flowered autonomously even under long-day conditions. In this study, CSVd-free and CSVd-infected plants were prepared by culturing different-sized dissected shoot apical meristems (SAMs) of 'Piato'. Using these CSVd-free and CSVd-infected plants, we clarified the relationship between CSVd infection and the autonomous flowering of 'Piato'. Under natural short-day conditions, the flowering of plants regenerated from SAMs containing leaf primordia (LPs) was 1 month earlier than plants regenerated from LP-free SAMs. CSVd was detected from these early flowering plants by reverse transcription-polymerase chain reaction. On the other hand, CSVd was not detected in plants regenerated from LP-free SAMs. CSVd-infected and CSVd-free plants were grown under long-day conditions simulated by night-break lighting at 22:00 p.m. to 2:00 a.m. All CSVd-infected plants flowered autonomously even under long-day conditions; on the other hand, CSVd-free chrysanthemum plants maintained their vegetative growth. When the CSVd-free plants were inoculated with CSVd by grafting them to CSVd-infected rootstocks, they flowered autonomously even under night-break lighting. In this study, the results suggest that CSVd may control the qualitative development process, flowering, i.e. CSVd can induce the autonomous flowering of chrysanthemum.

Effects of ethrel and gibberellin on impatiens plants

Impatiens ( Impatiens balsamina L.) is a qualitative short-day plant that flowers, in Israel, all year round. This lowers the quality of impatiens stock plants. The goal of this work was to examine treatments that will eliminate flowering in stock plants without reducing other qualities of the cutting crop. Impatiens plants (cv. Tempo Pink (Sultanii) and Aruba (New-Guinea)) were sprayed with ethrel alone or in combination with gibberellin. Ethrel treatment caused a transient increase in ethylene production and inhibited vegetative growth. A bi-weekly ethrel application, at 400 ppm and above, resulted in a complete elimination of flowering. Ethrel treatments led to an increase in cutting crop with a better rooting, but a shorter cutting length due to growth inhibition. Gibberellin, when applied in combination with ethrel, restored vegetative growth to control levels without affecting flowering.

Photoperiodic history affects the critical daylength of the short-day plantAcrosymphyton purpuriferum(Rhodophyta)

The crustose tetrasporophyte of the red alga Acrosymphyton purpuriferum is a qualitative short-day plant in the formation of its tetrasporangia. The critical daylength for the response was determined in plants precultured in various long-day regimes [20:4, 18:6, 16:8 and 14:10 (L:D, h)]. There was a strong influence of photoperiodic history. The sharper the decrease in daylength the stronger and faster the plants responded. The critical daylength (daylength inducing 50% response) increased from 9·5 h for plants precultured in 14 h days to 12·5 h for plants precultured in 20 h days. Acrosymphyton thus responds to a change in daylength, rather than to a fixed critical value. This is of adaptive significance in synchronising the onset of reproduction throughout its broad depth range in the subtidal region.

Photoperiodic induction of flowering in green and photobleachedChenopodium rubrum L. ecotype 184 - a short- day plant

Chenopodium rubrum L. ecotype 184 is a qualitative short-day plant with critical length of the night of eight hours that must be exceeded in order to flower: Five days after sowing, the plants were exposed to a various number of inductive cycles (14/10 h of däy/night cycle) to test the optimal photoperiodic conditions for flowering. In our experimental conditions the plants flowered with high percentage after more than four received inductive cycles, but there was no flowering below that. The plants grown on the herbicide Norflurazon (photobleached plants) showed different photoperiodic characteristics. There was negligible flowering of photobleached plants in the same experimental conditions as for the green ones.

A simulation model of kenaf for assisting fibre industry planning in northern Australia. I. General introduction and phenological model

The feasibility of utilizing kenaf (Hibiscus cannabinus L.) as a fibre crop and potential source of paper pulp is being investigated. This paper is the first in a series which develops and validates a simulation model of kenaf, and applies it to assessing the potential for dryland production in regions of tropical Australia. The duration from sowing to flowering is an important determinant of fibre yield in kenaf. Accordingly, the effect of temperature and photoperiod on the phenology of kenaf was examined. Data were collated from sowing-date experiments on kenaf cultivars Guatemala 4 and Everglades 71 at six locations in tropical Australia, ranging in latitude from 12� 54'S. to 19� 32'S. Data from one site, Kununurra, W.A. (15� 39'S.), was used to develop a model which described the duration from sowing to flowering in kenaf based on four stages: (1) sowing to emergence; (2) emergence to the end of the basic vegetative phase (BVP); (3) a photoperiod-induced phase (PIP) which ends at floral initiation; and (4) a flower development phase (FDP). Both kenaf cultivars responded as qualitative short-day plants where flowering did not occur above a critical photoperiod of 12.9 h. Assuming a base photoperiod of 12.0 h, the thermal time required to complete the BVP for the two cultivars was similar. However, photoperiod sensitivity during PIP, and the thermal time required for FDP, were greater for Guatemala 4 than for Everglades 71. Validation of the model against independently observed data for both cultivars at other sites resulted in close predictions in the thermal time required for flowering. This phenological model for kenaf can be used to assess the effect of sowing date on phenology at different locations in tropical environments, and is a key component of a crop growth simulation model to assess the environmental constraints to productivity in these regions.

Floral determination in the terminal bud of the short-day plant Pharbitis nil

Temporal and spatial aspects of floral determination in seedling terminal buds of the qualitative short-day plant Pharbitis nil were examined using a grafting assay. Floral determination in the terminal buds of 6-day-old P. nil seedlings is rapid; by 9 hr after the end of a 14-hr inductive dark period more than 50% of the induced terminal buds grafted onto uninduced stock plants produced a full complement of flower buds. When grafted at early times after the end of the dark period the terminal buds of induced plants produced three discrete populations of plants: plants with no flowers, plants with two axillary flowers at nodes 3 and 4 and a vegetative terminal shoot apex, and plants with five to seven flowers including a terminal flower. The temporal relationship among these populations of plants produced by apices grafted at different times indicates that under our conditions, the region of the terminal bud that will form the axillary buds at nodes 3 and 4 becomes florally determined prior to floral determination of the region of the terminal bud giving rise to the nodes above node 4.

Electrophoretic Analysis of Florally-Evoked Meristems of <italic>Pharbitis nil</italic> Choisy cv. Violet

Using high resolution 2-D PAGE and silver Staining, we investigated the changes in soluble proteins pracked by floral induction in the apical region of a qualitative short-day plant, Pharbitis nil. We chose to analyse the soluble proteins rather than the RNAs via translation in vitro

The influence of photoperiod on head formation in some Brachiaria species and Chloris gayana cv. Masaba.

The effect of the photoperiod on head formation was investigated in 5 Brachiaria spp. and selected ecotypes of C. gayana cv. Masaba. The experiments were conducted in the glasshouse with photoperiods of 10, 12 or 14 h in 1971 and 9, 10.25 or 12.5 h in 1973. The photoperiods comprised 9 h natural daylight in the summer, supplemented with 40 W incandescent lamps. It was concluded that B. mutica is a qualitative (obligate) short-day plant whereas B. ruziziensis and cv. Masaba are quantitative short-day plants. B. brizantha and B. decumbens were already flowering when exposed to 24-h photoperiods during the pre-experimental period in 1971. In Brachiaria introduction PI 299498, head formation in both experiments occurred a few days earlier under the short photoperiod treatment. In the later-formed heads of all grasses tested the number of racemes/head decreased, though the length of the racemes was not affected. During the 1971 experiment, culm branching was observed in most of the grasses. It was found that in Masaba "secondary" culms were mainly formed during photoperiods of 10 and 12 h but rarely in 14 h. "Tertiary" culms in B. ruziziensis were observed in photoperiods of 10 and 12 h. It is suggested that culm branching can be attributed to high RH. The low seed production of tropical grasses is mainly caused by the low number of heading tillers/unit area and the disynchronization of the flowering resulting from the long period of head production. It is suggested that more research on the photoperiodic response of these grasses would provide useful information on seed production. After selection of photosensitive cv. and seed production at lat. of approx. 15 deg N. and 15 deg S. the long period of heading would be reduced and the synchronization of the flowering would be improved. Some of the early heading types of Masaba are typical examples of photosensitive cv. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Effect of adenosine monophosphates on the flowering of Impatients balsamina L., a qualitative short-day plant

Adenosine monophosphates (AMPs) cause the induction of floral buds in Impatients balsamina L. under strictly non-inductive photoperiods and hasten it under inductive photoperiods, cyclic AMP being more effective than 3'- or 5'-AMPs in this regard.

Floral induction by 2,3,5-triiodobenzoic acid in Impatiens balsamina, a qualitative short-day plant

Floral buds were initiated in Impatiens balsamina plants treated with 2,3,5-triiodobenzoic acid (TIBA) and kept under non-inductive 16- and 24-hr photoperiods, although much later than under inductive 8-hr photoperiods. TIBA did not affect extension growth to any appreciable extent but decreased the number of nodes on the main shoot under 8-hr and increased it under 16- and 24-hr photoperiods. Its effect on the development of lateral buds varied with photoperiod. TIBA-induced flowering resembles gibberellin-induced one, but its mechanism is not clear.

Studies on Flowering Responses of Urena lobata

Urena lobata L. is a qualitative short-day plant with a critical dark period of about 12 hr. A minimum of 12 short days are required for floral initiation. Gibberellic acid (GA(3)) sprayed onto the leaves promoted flowering. The growth retardant, (2-chloroethyl)-trimethylammonium chloride (CCC) markedly inhibited flowering and stem elongation. This inhibition was reversed by subsequent application of GA(3).

Reproduction in Heteropogon contortus. I. Photoperiodic effects on flowering and sex expression

The flowering behaviour of selected Australian and African populations of Heteropogon contortus in response to a range of photoperiods was assessed in the Canberra phytotron (CERES) under a 30/25°C day/night temperature regime. Photoperiods comprised 8 hr of natural light supplemented with low intensity incandescent illumination to give a range between 10 and 18 hr in each photocycle. The patterns of response showed H. contortus to be a short-day plant. Lines from both Australian and African populations originating from lower latitudes, and late-flowering when grown in a grass garden, flowered only in photoperiods shorter than 12 hr, remaining vegetative at longer day lengths. These were qualitative short-day plants. In contrast, the early-flowering lines showed either a qualitative or a quantitative short-day response; the latter flowered in all photoperiods but more rapidly at shorter day lengths. The nature of the early- and late-flowering behaviour is explained on the basis of the short-day responses and climatic adaptation. Since the inflorescences are polygamous, a sex ratio was calculated for all inflorescences formed by using the ratio of number of male+male spikelet pairs v. the number of female+male spikelet pairs. Increasing the photoperiod resulted in inflorescences containing more male spikelets and fewer awned female spikelets. From this it appears that day length exerts some influence over the determination of sex, and thus of seed production, in H. contortus. Versatility of this kind may well have adaptive significance depending on the breeding system in that it can partially control population heterogeneity and thus be of phytogeographic significance.

Floral induction by gibberellic acid in Impatiens balsamina, a qualitative short-day plant

In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants.