Drought and Darkness during Long-Term Simulated Shipping Delay Post-Shipping Flowering of Phalaenopsis Sogo Yukidian ‘V3’

: We investigated the relationship between simulated shipping (SS) without watering or light and post-shipping growth and ﬂowering of Phalaenopsis Sogo Yukidian ‘V3’. Two experimental environments were created: a low-temperature chamber for simulated shipping and a growth chamber for simulated ﬁnishing at the destination. Plants from both the control and treatment groups were moved from the low-temperature chamber to the growth chamber after the end of the simulated shipping. Control plants received continuous light and regular irrigation; plants in the treatment group were placed in the low-temperature chamber under light (LSS) or dark (DSS) conditions for 10, 20, 30, 40, or 50 days, without irrigation. Once DSS duration exceeded 40 days, the leaf-yellowing rate increased rapidly. Chlorophyll content decreased from day 10 to 30 of DSS and slightly increased in LSS and DSS over 40 days. The photochemical reﬂectance index decreased with the SS duration. The maximum quantum yield PSII photochemistry (Fv/Fm) values sharply decreased after the end of SS; after 40 days, neither LSS nor DSS plants recovered to the normal range. In the same SS duration, the number of days to spiking was delayed in the DSS. In addition, the number of days to spiking was delayed, owing to the longer SS duration. LSS for 50 days induced early ﬂowering, as in the control group, but lowered ﬂower quality. The results demonstrate that drought stress from long-term shipping (>40 days) delayed ﬂowering. In particular, DSS delayed ﬂowering more than LSS due to the decrease in chlorophyll content and the reduction in carbohydrates through respiration.


Introduction
Moth orchids (Phalaenopsis spp.) originate from tropical and subtropical areas of Asia, where annual temperatures range from 20 to 27 • C. These are epiphytic orchids that mainly grow under the canopy in tropical rainforests [1,2]. Phalaenopsis spp., which are Crassulacean acid metabolism (CAM) plants, have a low light demand and a special photosynthesis mechanism by which the stomata open during the night to fix CO 2 in the form of organic acids and then close during the day, preventing water loss and allowing the reuse of CO 2 from respiration for photosynthesis [3,4]. Phalaenopsis spp. are very popular as potted plants and cut flowers because of their high ornamental value-in particular, the various shapes, sizes, and colors of the flowers-and long flower life [5]. They are also commercially grown and exported on a large scale, thus reducing production costs. Global demand for these orchids continues to increase [6].
Phalaenopsis spp. have different ecological and physiological characteristics from those of general potted flowering plants and require a specific temperature range at each stage of production for high-quality commercial production [1]. Maintaining an ambient temperature of 28-30°C in the vegetative phase suppresses flowering and promotes leaf growth. During the spiking (emergence of an inflorescence) phase, the temperature is lowered to 18-23°C to induce the appearance of the spike. During the flowering and RH 30.4 ± 0.7%). The photoperiod was 9 h (from 09:00 to 18:00) with photosynthetic flux density (PPFD) 150 ± 10 µmol·m −2 ·s −1 using bar-type, warm-white LEDs (57 cm × 2.3 cm × 3.5 cm, LZT5-08L, Sunsea Industry Co., Ltd., Jiangmen, China).

Simulated Shipping Conditions
The volumetric water content (VWC) of Sphagnum moss was 22 ± 3% before packaging for simulated shipping, following the NIHHS guidelines [17]. Twelve plants were packed in each paper box and placed in a low-temperature chamber without irrigation for the simulated shipping duration. The control plants were placed under continuous light and irrigation in the low-temperature chamber for 40 days and moved to the growth chamber. Plants of each treatment group were placed in a low-temperature chamber under light (LSS) or dark (DSS, packed in a paper box) condition without irrigation during each simulated shipping duration for 10, 20, 30, 40, or 50 days and moved to the growth chamber after the end of simulated shipping ( Figure 1B,C). Plants in the growth chamber were irrigated every 10 days with tap water.

Measurements of Photochemical Reflectance Index and Chlorophyll Fluorescence
The photochemical reflectance index (PRI) of the uppermost mature leaves was measured using a PolyPen RP400 (Photon Systems Instruments, Drásov, Czech Republic) at the end of each simulated shipping. Chlorophyll fluorescence of the uppermost mature leaves was measured using a FluorPen FP100 (Photon Systems Instruments) every 10 days from the end of each simulated shipping. The leaves were clamped with dark adaptation clips for 30 min. The minimal chlorophyll fluorescence (Fo) was then determined, followed by maximal chlorophyll fluorescence (Fm) measurements. The yield of variable chlorophyll fluorescence (Fv = Fm − Fo) and the maximum quantum yield PSII photochemistry (Fv/Fm) were measured.

Data Collection and Statistical Analysis
The VWC of Sphagnum moss was measured using a soil moisture sensor (TEROS12, METER Group, Inc., Pullman, WA, USA) and a data logger (ZSC Bluetooth Sensor Inter-

Simulated Shipping Conditions
The volumetric water content (VWC) of Sphagnum moss was 22 ± 3% before packaging for simulated shipping, following the NIHHS guidelines [17]. Twelve plants were packed in each paper box and placed in a low-temperature chamber without irrigation for the simulated shipping duration. The control plants were placed under continuous light and irrigation in the low-temperature chamber for 40 days and moved to the growth chamber. Plants of each treatment group were placed in a low-temperature chamber under light (LSS) or dark (DSS, packed in a paper box) condition without irrigation during each simulated shipping duration for 10, 20, 30, 40, or 50 days and moved to the growth chamber after the end of simulated shipping ( Figure 1B,C). Plants in the growth chamber were irrigated every 10 days with tap water.

Measurements of Photochemical Reflectance Index and Chlorophyll Fluorescence
The photochemical reflectance index (PRI) of the uppermost mature leaves was measured using a PolyPen RP400 (Photon Systems Instruments, Drásov, Czech Republic) at the end of each simulated shipping. Chlorophyll fluorescence of the uppermost mature leaves was measured using a FluorPen FP100 (Photon Systems Instruments) every 10 days from the end of each simulated shipping. The leaves were clamped with dark adaptation clips for 30 min. The minimal chlorophyll fluorescence (Fo) was then determined, followed by maximal chlorophyll fluorescence (Fm) measurements. The yield of variable chlorophyll fluorescence (Fv = Fm − Fo) and the maximum quantum yield PSII photochemistry (Fv/Fm) were measured.

Data Collection and Statistical Analysis
The VWC of Sphagnum moss was measured using a soil moisture sensor (TEROS12, METER Group, Inc., Pullman, WA, USA) and a data logger (ZSC Bluetooth Sensor Interface, METER Group, Inc.) at the end of simulated shipping. Temperature and relative humidity in the boxes were measured during each simulated shipping using a temperature/humidity meter (TH-05, Daekwang, Inc., Seoul, Korea).
The leaf length, width, and chlorophyll content of the uppermost mature leaves were measured for twelve plants in each treatment every 10 days during the experiment. Chlorophyll content (SPAD) was measured using a chlorophyll meter (SPAD-502plus, Konica Minolta, Japan) while avoiding the central leaf vein. The number of leaves with lengths ≥ 6 cm was counted. Yellowed leaves were defined as leaves in which more than 20% of their surface was yellow or the basal part became yellow for 10 days from the end of each simulated shipping. The rate of leaf yellowing was defined as the percentage of the number of yellow leaves on the total number of leaves in each plant.
Spiking was defined as the emergence of a spike ≥ 1 cm from the base of the leaf, and days to spiking and spike length were measured. Flowering was recorded when the first floret petal was fully unfolded, and days to flowering and number of flower buds (≥2 mm) were measured. Measurements of flowering characteristics were completed at 170 days after the start of the experiment. Comparisons of treatment means were performed using Duncan's multiple range test at p < 0.05, using SPSS Statistics program (IBM SPSS Statistics ver.23, IBM, Armonk, NY, USA).

Results and Discussion
VWC decreased as the duration of the simulated shipping increased in both the LSS and DSS treatments (Figure 2). At the end of LSS_10 and DSS_10, there was a 56.1% and 32.7% reduction, respectively, compared to before the start of simulated shipping (22 ± 3%). Until DSS_30, the VWC of the DSS group was higher than or similar to that of LSS plants because the humidity around plants was kept relatively high in the boxes during DSS (data not shown). There was no difference in the VWC in either group in the simulated shipping treatment once the shipping duration exceeded 40 days.
face, METER Group, Inc.) at the end of simulated shipping. Temperature and relative humidity in the boxes were measured during each simulated shipping using a temperature/humidity meter (TH-05, Daekwang, Inc., Seoul, Korea).
The leaf length, width, and chlorophyll content of the uppermost mature leaves were measured for twelve plants in each treatment every 10 days during the experiment. Chlorophyll content (SPAD) was measured using a chlorophyll meter (SPAD-502plus, Konica Minolta, Japan) while avoiding the central leaf vein. The number of leaves with lengths ≥ 6 cm was counted. Yellowed leaves were defined as leaves in which more than 20% of their surface was yellow or the basal part became yellow for 10 days from the end of each simulated shipping. The rate of leaf yellowing was defined as the percentage of the number of yellow leaves on the total number of leaves in each plant.
Spiking was defined as the emergence of a spike ≥ 1 cm from the base of the leaf, and days to spiking and spike length were measured. Flowering was recorded when the first floret petal was fully unfolded, and days to flowering and number of flower buds (≥2 mm) were measured. Measurements of flowering characteristics were completed at 170 days after the start of the experiment. Comparisons of treatment means were performed using Duncan's multiple range test at p < 0.05, using SPSS Statistics program (IBM SPSS Statistics ver.23, IBM, Armonk, NY, USA).

Results and Discussion
VWC decreased as the duration of the simulated shipping increased in both the LSS and DSS treatments (Figure 2). At the end of LSS_10 and DSS_10, there was a 56.1% and 32.7% reduction, respectively, compared to before the start of simulated shipping (22 ± 3%). Until DSS_30, the VWC of the DSS group was higher than or similar to that of LSS plants because the humidity around plants was kept relatively high in the boxes during DSS (data not shown). There was no difference in the VWC in either group in the simulated shipping treatment once the shipping duration exceeded 40 days. There was no difference in the leaf-yellowing rate measured at the end of simulated shipping in LSS plants at different shipping durations. After DSS, the leaf-yellowing rate tended to increase as the duration of simulated shipping increased ( Figure 3). Yellowed leaves occur due to increased abscisic acid (ABA) content after dark storage of Phalaenopsis There was no difference in the leaf-yellowing rate measured at the end of simulated shipping in LSS plants at different shipping durations. After DSS, the leaf-yellowing rate tended to increase as the duration of simulated shipping increased ( Figure 3). Yellowed leaves occur due to increased abscisic acid (ABA) content after dark storage of Phalaenopsis under drought stress [16]. There was no difference in VWC values between LSS and DSS plants in simulated shipping for more than 40 days, but the leaf-yellowing rates of DSS 40 (16.9%) and DSS_50 (36.3%) were higher than those of LSS_40 (2.5%) and LSS_50 (1.2%). Similar to Phalaenopsis, species of Xerosicyos, another taxon of CAM plants, increased ABA content under drought stress and closed stomata, even at night, to reduce water loss [18]. In addition, stomatal closure during the night reduced gas exchange for photosynthesis.
Drought stress decreased carbohydrate content in 'Tinny Tender' Doritaenopsis, which is genetically and physiologically close to Phalaenopsis [19]. However, chlorophyll and soluble protein contents were maintained under drought stress in light-exposed Xerosicyos [18]. Therefore, in this study, the chlorophyll content of Phalaenopsis leaves could be maintained under light conditions during long-term simulated shipping. Although drought stress under light can reduce the photosynthetic rate by stomatal closure, thereby lowering the carbohydrate content in Phalaenopsis, it is estimated that leaves with low yellowing rates under light and water stress can maintain photosynthesis at some level, using carbon dioxide from their own respiration. under drought stress [16]. There was no difference in VWC values between LSS and DSS plants in simulated shipping for more than 40 days, but the leaf-yellowing rates of DSS 40 (16.9%) and DSS_50 (36.3%) were higher than those of LSS_40 (2.5%) and LSS_50 (1.2%). Similar to Phalaenopsis, species of Xerosicyos, another taxon of CAM plants, increased ABA content under drought stress and closed stomata, even at night, to reduce water loss [18]. In addition, stomatal closure during the night reduced gas exchange for photosynthesis. Drought stress decreased carbohydrate content in 'Tinny Tender' Doritaenopsis, which is genetically and physiologically close to Phalaenopsis [19]. However, chlorophyll and soluble protein contents were maintained under drought stress in light-exposed Xerosicyos [18]. Therefore, in this study, the chlorophyll content of Phalaenopsis leaves could be maintained under light conditions during long-term simulated shipping. Although drought stress under light can reduce the photosynthetic rate by stomatal closure, thereby lowering the carbohydrate content in Phalaenopsis, it is estimated that leaves with low yellowing rates under light and water stress can maintain photosynthesis at some level, using carbon dioxide from their own respiration. The chlorophyll content (SPAD) of Phalaenopsis leaves after each of the durations of DSS decreased compared to values before simulated shipping and were lower than the corresponding values in LSS plants at all durations of treatment ( Figure 4). Chlorophyll content of water dropwort leaves (Oenanthe javanica DC) decreased as the dark treatment period increased, apparently because chlorophyll decomposition was promoted in the dark without photosynthesis and chlorophyll synthesis [20]. However, in this study, the reduction rate of chlorophyll content was slightly lower during simulated shipping lasting more than 40 days. One of the responses to drought stress in purslane (Portulaca oleracea L.), a succulent plant, is to maintain or increase the chlorophyll content, which reduces oxidative damage in drought-stressed plants [21,22]. Similar responses were observed in Phalaenopsis, which, like purslane, is a CAM and succulent plant. The increase in chlorophyll content in LSS_40 and LSS_50 can be assumed to be a phenomenon caused by the addition of light to drought-stressed plants. The chlorophyll content (SPAD) of Phalaenopsis leaves after each of the durations of DSS decreased compared to values before simulated shipping and were lower than the corresponding values in LSS plants at all durations of treatment ( Figure 4). Chlorophyll content of water dropwort leaves (Oenanthe javanica DC) decreased as the dark treatment period increased, apparently because chlorophyll decomposition was promoted in the dark without photosynthesis and chlorophyll synthesis [20]. However, in this study, the reduction rate of chlorophyll content was slightly lower during simulated shipping lasting more than 40 days. One of the responses to drought stress in purslane (Portulaca oleracea L.), a succulent plant, is to maintain or increase the chlorophyll content, which reduces oxidative damage in drought-stressed plants [21,22]. Similar responses were observed in Phalaenopsis, which, like purslane, is a CAM and succulent plant. The increase in chlorophyll content in LSS_40 and LSS_50 can be assumed to be a phenomenon caused by the addition of light to drought-stressed plants. Measurements of the photochemical reflectance index (PRI) indicate the instantaneous photosynthesis efficiency; thus, decreasing PRI is considered a stress indicator in drought-stressed plants [23]. The PRI before the simulated shipping was −0.0091, and after 30 days, the PRI values of LSS tended to decrease as the simulated shipping duration increased ( Figure 5). This is thought to be due to the combination of drought stress and light conditions in long-term LSS. In high-light environments, stressed Phalaenopsis plants had lower PRI values due to an increase in photosynthetic photon flux density (PPFD) [24]. The light intensity set in this study was not a high level for Phalaenopsis. However, the accumulated light amount for the growing period was considered to be additively stressful for Phalaenopsis plants under drought stress, as inferred by the reduced PRI values.  Measurements of the photochemical reflectance index (PRI) indicate the instantaneous photosynthesis efficiency; thus, decreasing PRI is considered a stress indicator in droughtstressed plants [23]. The PRI before the simulated shipping was −0.0091, and after 30 days, the PRI values of LSS tended to decrease as the simulated shipping duration increased ( Figure 5). This is thought to be due to the combination of drought stress and light conditions in long-term LSS. In high-light environments, stressed Phalaenopsis plants had lower PRI values due to an increase in photosynthetic photon flux density (PPFD) [24]. The light intensity set in this study was not a high level for Phalaenopsis. However, the accumulated light amount for the growing period was considered to be additively stressful for Phalaenopsis plants under drought stress, as inferred by the reduced PRI values.  Measurements of the photochemical reflectance index (PRI) indicate the instantaneous photosynthesis efficiency; thus, decreasing PRI is considered a stress indicator in drought-stressed plants [23]. The PRI before the simulated shipping was −0.0091, and after 30 days, the PRI values of LSS tended to decrease as the simulated shipping duration increased ( Figure 5). This is thought to be due to the combination of drought stress and light conditions in long-term LSS. In high-light environments, stressed Phalaenopsis plants had lower PRI values due to an increase in photosynthetic photon flux density (PPFD) [24]. The light intensity set in this study was not a high level for Phalaenopsis. However, the accumulated light amount for the growing period was considered to be additively stressful for Phalaenopsis plants under drought stress, as inferred by the reduced PRI values.  The Fv/Fm value of chlorophyll fluorescence refers to the maximum quantum yield of PSII, which decreases when plants are stressed, and is used as a stress indicator. The ratio of Fv/Fm is typically in the range of 0.75-0.85 when plants are not stressed by environmental factors [25]. In this study, the Fv/Fm of plants before the start of simulated shipping ranged from 0.73 to 0.78. Fv/Fm values were measured before and after simulated shipping every 10 days (Figure 6). Immediately after the end of the simulated shipping, the overall Fv/Fm in the LSS treatment group was lower than that of DSS plants. This indicates that the Fv/Fm value further decreased because of the addition of lighting to drought stress. In most LSS and DSS treatment groups, as well as the controls, the Fv/Fm value at 30 days after the simulation shipping returned to the normal range. Fifty days after the simulation, neither LSS_40 nor DSS_40 returned to the normal range. In particular, the Fv/Fm value of DSS_50 plants was the lowest compared to the other treatments. The Fv/Fm value of chlorophyll fluorescence refers to the maximum quantum yield of PSII, which decreases when plants are stressed, and is used as a stress indicator. The ratio of Fv/Fm is typically in the range of 0.75-0.85 when plants are not stressed by environmental factors [25]. In this study, the Fv/Fm of plants before the start of simulated shipping ranged from 0.73 to 0.78. Fv/Fm values were measured before and after simulated shipping every 10 days (Figure 6). Immediately after the end of the simulated shipping, the overall Fv/Fm in the LSS treatment group was lower than that of DSS plants. This indicates that the Fv/Fm value further decreased because of the addition of lighting to drought stress. In most LSS and DSS treatment groups, as well as the controls, the Fv/Fm value at 30 days after the simulation shipping returned to the normal range. Fifty days after the simulation, neither LSS_40 nor DSS_40 returned to the normal range. In particular, the Fv/Fm value of DSS_50 plants was the lowest compared to the other treatments. The spiking rate reached 100% in the control group, and when compared with the same day after treatment, the spiking rate of LSS plants was higher than that of the DSS group (Figure 7). In the LSS plants, the LSS_20 group was the first to show a spiking rate of 50%, followed by LSS_10, 30, and 40. The spiking rate of LSS_50 was 66.7% on day 70, the highest among the LSS treatment groups in the same period. In DSS plants, the spiking rate of DSS_20 first reached 66.7% at 110 days after treatment and reached 100% with DSS_10 after 120 days. DSS_40 and DSS_50 showed the lowest rates after 140 days of treatment. The spiking rate reached 100% in the control group, and when compared with the same day after treatment, the spiking rate of LSS plants was higher than that of the DSS group (Figure 7). In the LSS plants, the LSS_20 group was the first to show a spiking rate of 50%, followed by LSS_10, 30, and 40. The spiking rate of LSS_50 was 66.7% on day 70, the highest among the LSS treatment groups in the same period. In DSS plants, the spiking rate of DSS_20 first reached 66.7% at 110 days after treatment and reached 100% with DSS_10 after 120 days. DSS_40 and DSS_50 showed the lowest rates after 140 days of treatment. Days to spiking tended to increase as the shipping duration increased, and the number of days to spiking in DSS was greater than that of LSS plants in the same shipping period (Figure 8). In a previous study, it was shown that after Phalaenopsis 'V3' plants were stored at 20 °C in the dark condition for 0-40 days, the photosynthate content in the shoots Days to spiking tended to increase as the shipping duration increased, and the number of days to spiking in DSS was greater than that of LSS plants in the same shipping period (Figure 8). In a previous study, it was shown that after Phalaenopsis 'V3' plants were stored at 20 • C in the dark condition for 0-40 days, the photosynthate content in the shoots and roots significantly decreased in the first 10 days of storage [26]. In particular, after 40 days of dark storage, the photosynthate in shoots decreased by 51% compared to that before the experiment. In the present study, the spiking rate decreased with increasing DSS duration due to the continuous reduction in carbohydrates during respiration. The spiking rate under LSS treatment is estimated to be relatively high due to the accumulation of carbohydrates in photosynthesis. Days to spiking tended to increase as the shipping duration increased, and the number of days to spiking in DSS was greater than that of LSS plants in the same shipping period (Figure 8). In a previous study, it was shown that after Phalaenopsis 'V3' plants were stored at 20 °C in the dark condition for 0-40 days, the photosynthate content in the shoots and roots significantly decreased in the first 10 days of storage [26]. In particular, after 40 days of dark storage, the photosynthate in shoots decreased by 51% compared to that before the experiment. In the present study, the spiking rate decreased with increasing DSS duration due to the continuous reduction in carbohydrates during respiration. The spiking rate under LSS treatment is estimated to be relatively high due to the accumulation of carbohydrates in photosynthesis. In the LSS group, there was no significant difference in the number of days to spiking among LSS_10, LSS_20, and control plants (Figure 8). The spiking rate began to slow in LSS_30 and was slowest in LSS_40. However, spiking suddenly accelerated in LSS_50, and spikes occurred at the same time as in the control group. In CAM plants, the stomata open and absorb CO2 during the night, and light is involved in stomatal opening and In the LSS group, there was no significant difference in the number of days to spiking among LSS_10, LSS_20, and control plants (Figure 8). The spiking rate began to slow in LSS_30 and was slowest in LSS_40. However, spiking suddenly accelerated in LSS_50, and spikes occurred at the same time as in the control group. In CAM plants, the stomata open and absorb CO 2 during the night, and light is involved in stomatal opening and closing [27]. Under drought stress, the stomata of CAM plants remain closed throughout the day and night and are unable to absorb the CO 2 normally required for photosynthesis. Consequently, CO 2 in drought-stressed CAM plants is recycled for photosynthesis, which reduces organic acid accumulation [28]. For this reason, if Phalaenopsis plants are placed under continuous drought conditions for more than 30 days (to simulate shipping), the reduction in organic acids related to the opening and closing of the stomata is also expected to affect subsequent spiking.
In LSS_50 plants, the spiking rate was 16.7% on day 50, the end day of simulated shipping, and this group was the first to reach 66.7% on day 60. The spiking rate in LSS_50 plants was the greatest among the LSS treatments, and spiking occurred at the same time as in the control group (Figure 7).
There was no significant difference in the length and width of the uppermost mature leaves among the plants under different simulated shipping durations (Table 1). Neither was there a significant difference in the number of new leaves that occurred during the 100 days after the start of the simulated shipping. z Spike length at 160 days after the start of simulated shipping. y Bud at 170 days after start of simulated shipping. x Means within columns followed by different letters are significantly different according to Duncan's honestly significant difference test at p < 0.05. NS, *, **, *** Not significant or significant at p ≤ 0.05, 0.01, or 0.001, respectively.
Spike length was greater, as was the size of the first floret or bud, in the control and LSS_50 groups compared to the plants in other treatments (Table 1). In the control and LSS_50 groups, the number of flower buds in the spike was also greater, and the number of days to visible flower bud was less than in other treatments. The length of the first floret or bud and the number of buds tended to decrease under dark conditions and with increasing shipping duration (Figure 9). Therefore, growth of the uppermost mature leaf and new leaf at 100 days after the start of simulated shipping and subsequent flowering quality of Phalaenopsis Sogo Yukidian 'V3' were affected by light condition and shipping duration. There was no difference in the characteristics of vegetative growth, but the characteristics of flowering in the more rapidly flowering plants were superior to those in the other plants. This is because the plants were mature enough to flower in low-temperature and light conditions during simulated shipping induced spiking more quickly than under dark conditions. This can be explained by the accumulation of photosynthates. Aechmea 'Maya' plants under supplemental lighting (30 µmol·m −2 ·s −1 PPFD) accumulated more malic acid than shaded plants, severe light limitation (0.46 µmol·m −2 ·s −1 PPFD), over the course of 6 days [29].
Horticulturae 2021, 7, x FOR PEER REVIEW 11 of 15 Spike length was greater, as was the size of the first floret or bud, in the control and LSS_50 groups compared to the plants in other treatments (Table 1). In the control and LSS_50 groups, the number of flower buds in the spike was also greater, and the number of days to visible flower bud was less than in other treatments. The length of the first floret or bud and the number of buds tended to decrease under dark conditions and with increasing shipping duration (Figure 9). Therefore, growth of the uppermost mature leaf and new leaf at 100 days after the start of simulated shipping and subsequent flowering quality of Phalaenopsis Sogo Yukidian 'V3' were affected by light condition and shipping duration. There was no difference in the characteristics of vegetative growth, but the characteristics of flowering in the more rapidly flowering plants were superior to those in the other plants. This is because the plants were mature enough to flower in low-temperature and light conditions during simulated shipping induced spiking more quickly than under dark conditions. This can be explained by the accumulation of photosynthates. Aechmea  Since the plants of LSS_50 and the control spiked fastest (Figure 8), the flowering characteristics of LSS_50 and the control at 100 and 130 days after the start of the simulated shipping were compared (Figures 10 and 11). There were no significant differences in the spike length between LSS_50 and the control. However, the number of buds and flowers and the size of flower buds and florets in LSS_50 was less than that in the control plants; that is, the flowering of LSS_50 plants was rapid, similar to that of the control, but the quality-related characteristics of the flowering potted plant, such as flower number and size, were not sufficient in LSS-50 ( Figure 11). The early flowering of drought-stressed plants in LSS_50 can be explained as a kind of drought escape mechanism in the way that plants escape under drought conditions [30]. Averrhoa carambola promotes flowering as the accumulation of carbohydrates increases under drought stress [31]. It has been reported that when flowering was accelerated by drought stress, it shortened vegetative growth and the time to produce photosynthates, thereby resulting in low quality of flowers [30]. No irrigation for 50 days of the simulated shipping induced drought stress in Phalaenopsis 'V3' and accelerated spiking and flowering compared with other treatment Since the plants of LSS_50 and the control spiked fastest (Figure 8), the flowering characteristics of LSS_50 and the control at 100 and 130 days after the start of the simulated shipping were compared (Figures 10 and 11). There were no significant differences in the spike length between LSS_50 and the control. However, the number of buds and flowers and the size of flower buds and florets in LSS_50 was less than that in the control plants; that is, the flowering of LSS_50 plants was rapid, similar to that of the control, but the quality-related characteristics of the flowering potted plant, such as flower number and size, were not sufficient in LSS-50 ( Figure 11). The early flowering of drought-stressed plants in LSS_50 can be explained as a kind of drought escape mechanism in the way that plants escape under drought conditions [30]. Averrhoa carambola promotes flowering as the accumulation of carbohydrates increases under drought stress [31]. It has been reported that when flowering was accelerated by drought stress, it shortened vegetative growth and the time to produce photosynthates, thereby resulting in low quality of flowers [30]. No irrigation for 50 days of the simulated shipping induced drought stress in Phalaenopsis 'V3' and accelerated spiking and flowering compared with other treatment groups; however, the drought stress also lowered the flower quality, such as the number and size of florets, compared to the control plants measured at the same time ( Figure 11).
Horticulturae 2021, 7, x FOR PEER REVIEW 12 of 15 groups; however, the drought stress also lowered the flower quality, such as the number and size of florets, compared to the control plants measured at the same time ( Figure 11).

Conclusions
For more than 40 days of simulated shipping, Phalaenopsis plants were subjected to drought stress. Drought-stressed plants increase the concentration of ABA [32], which can be evaluated by their leaf-yellowing rate [33], photochemical reflectance index (PRI), and chlorophyll fluorescence (Fv/Fm). When the simulated shipping was carried out for more than 40 days under dark conditions, the leaf-yellowing rate significantly increased-and increased sharply after more than 50 days. The PRI value, which is a measure of instantaneous photosynthesis efficiency and thus an indicator of stress, tended to decrease with increasing simulated shipping duration in LSS plants. The PRI increased for 20 days in DSS plants, presumably because the humidity inside the boxes for simulated shipping groups; however, the drought stress also lowered the flower quality, such as the number and size of florets, compared to the control plants measured at the same time ( Figure 11).

Conclusions
For more than 40 days of simulated shipping, Phalaenopsis plants were subjected to drought stress. Drought-stressed plants increase the concentration of ABA [32], which can be evaluated by their leaf-yellowing rate [33], photochemical reflectance index (PRI), and chlorophyll fluorescence (Fv/Fm). When the simulated shipping was carried out for more than 40 days under dark conditions, the leaf-yellowing rate significantly increased-and increased sharply after more than 50 days. The PRI value, which is a measure of instantaneous photosynthesis efficiency and thus an indicator of stress, tended to decrease with increasing simulated shipping duration in LSS plants. The PRI increased for 20 days in DSS plants, presumably because the humidity inside the boxes for simulated shipping

Conclusions
For more than 40 days of simulated shipping, Phalaenopsis plants were subjected to drought stress. Drought-stressed plants increase the concentration of ABA [32], which can be evaluated by their leaf-yellowing rate [33], photochemical reflectance index (PRI), and chlorophyll fluorescence (Fv/Fm). When the simulated shipping was carried out for more than 40 days under dark conditions, the leaf-yellowing rate significantly increased-and increased sharply after more than 50 days. The PRI value, which is a measure of instantaneous photosynthesis efficiency and thus an indicator of stress, tended to decrease with increasing simulated shipping duration in LSS plants. The PRI increased for 20 days in DSS plants, presumably because the humidity inside the boxes for simulated shipping was maintained to some extent, and thus, the drought stress was relatively low. Subsequent drought stress in Phalaenopsis tended to decrease PRI values. The value of Fv/Fm decreased in most treatments immediately after the end of the simulated shipping and tended to recover afterwards. In the case of the LSS_40 treatment group, the reduction rate was the highest compared to the other treatments, which indicates that light increases stress during drought stress. Both LSS and DSS groups under simulated shipping conditions for more than 40 days did not recover to the normal range of Fv/Fm measured at 50 days after simulated shipping; in particular, DSS_50 plants showed a continuous decline in Fv/Fm values.
Spiking was delayed in all Phalaenopsis plants in the LSS and DSS treatments due to drought stress. Under dark conditions, Phalaenopsis under drought stress does not photosynthesize and only responds with closed stomata. Consequently, in DSS, only chlorophyll degradation continued without further production, leading to a decrease in chlorophyll content; furthermore, only respiration without photosynthesis continued, leading to a decrease in carbohydrate concentration, which delayed flowering more than LSS. It is estimated that Phalaenopsis under drought stress and light conditions (LSS) will exhibit relatively little flowering delay compared to DSS plants due to the increase in the C/N ratio that occurs with accumulation of photosynthate under light. As an exception, LSS_50 induced early flowering in Phalaenopsis Sogo Yukidian 'V3', an expected mechanism for escape from drought stress, but reduced flower quality and decreased the number and size of flowers ( Figure 12).
Horticulturae 2021, 7, x FOR PEER REVIEW was maintained to some extent, and thus, the drought stress was relatively low. quent drought stress in Phalaenopsis tended to decrease PRI values. The value of decreased in most treatments immediately after the end of the simulated shippin tended to recover afterwards. In the case of the LSS_40 treatment group, the red rate was the highest compared to the other treatments, which indicates that light in stress during drought stress. Both LSS and DSS groups under simulated shipping tions for more than 40 days did not recover to the normal range of Fv/Fm measure days after simulated shipping; in particular, DSS_50 plants showed a continuous d in Fv/Fm values.
Spiking was delayed in all Phalaenopsis plants in the LSS and DSS treatments drought stress. Under dark conditions, Phalaenopsis under drought stress does not synthesize and only responds with closed stomata. Consequently, in DSS, only phyll degradation continued without further production, leading to a decrease in phyll content; furthermore, only respiration without photosynthesis continued, lea a decrease in carbohydrate concentration, which delayed flowering more than LS estimated that Phalaenopsis under drought stress and light conditions (LSS) will relatively little flowering delay compared to DSS plants due to the increase in th ratio that occurs with accumulation of photosynthate under light. As an exception, induced early flowering in Phalaenopsis Sogo Yukidian 'V3', an expected mechani escape from drought stress, but reduced flower quality and decreased the numb size of flowers ( Figure 12). The flowering delay that occurs when plants are shipped over 40 days in da ditions is affected by both drought and dark conditions. Therefore, the duration o shipping for Phalaenopsis trade must be completed within 40 days. Further stud needed to determine how to relieve drought stress and reduce carbohydrate loss piration during long-term shipping.  The flowering delay that occurs when plants are shipped over 40 days in dark conditions is affected by both drought and dark conditions. Therefore, the duration of dark shipping for Phalaenopsis trade must be completed within 40 days. Further studies are needed to determine how to relieve drought stress and reduce carbohydrate loss by respiration during long-term shipping.