Average daily light integral (DLI) and temperature of the greenhouse (red) and indoor (blue) environments used in two experimental runs evaluating compact pepper plants for container gardening. In the temperature graphs, solid and dashed lines indicate average data collected during the day and night, respectively; (1.8 × °C) + 32 = °F.
Effect of growth index on total fruit fresh weight per plant produced by compact pepper cultivars grown in a greenhouse (A) or indoors (B). Growth index was calculated using the formula π × h × r2, where h is plant height and r is calculated by multiplying ½ times the mean of two canopy widths. Cultivar names are detailed in Table 1; 1 m3 = 35.3147 ft3, 1 g = 0.0353 oz.
Intumescence on abaxial leaf surface of ‘Spicy Jane’ pepper.
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Numerous compact pepper (Capsicum annuum) cultivars are available for home gardening. However, evaluations under different environmental conditions are limited. This study aimed to characterize growth and productivity of 14 compact pepper cultivars grown indoors under environmental conditions that simulated a residential space (11 mol·m−2·d−1 provided by white of light-emitting diode fixtures, constant 22 °C, and moderate relative humidity of 40% to 60%) and in a greenhouse with sunlight only. Plants in the greenhouse were generally larger in size and produced more fruit [both in number and total fresh weight (FW)] than those grown indoors. For example, growth index, which is a measure of canopy volume that integrates shoot height and width, and fruit FW were up to 250% and 621% higher in the greenhouse than indoors, respectively. ‘Fresh Bites Red Improved’ and ‘Sweet Yellow’ had the highest fruit FW per plant when grown in the greenhouse (695 g) and indoors (483 g), respectively. All cultivars evaluated in this study are recommended for gardening under sunlight, and most for indoor gardening except for Cosmo, Pinata, and Yellow Tomato, which had the lowest fruit FW when grown indoors (61, 59, and 52 g) and thus, should not be recommended to consumers aiming to maximize fruit yield. In addition, ‘Cayennetta’, ‘Cheyenne’, ‘Hot Tomato Red’, ‘Pinata’, ‘Spicy Jane’, and ‘Sweet Yellow’ were affected by intumescence, which could negatively affect indoor gardening experiences until widespread recommendations to mitigate this disorder become available.
In 2019, US sales of edible and ornamental pepper (Capsicum annuum) plants for the home gardening market were valued at $38.5 million and $1.7 million, respectively [US Department of Agriculture (USDA) 2020]. Edible pepper is followed only by tomato (Solanum lycopersicum) and culinary herbs as the most popular vegetable-type bedding plants sold in the United States (USDA 2020). Home gardeners who grow peppers for edible use often prefer high-yielding and disease-resistant plants (Kirkpatrick and Davison 2018; Sykes et al. 2021), whereas those who grow them for ornamental purposes prefer small plants with colorful fruit that maintain visual harmony within the landscape (do Nascimento Costa et al. 2019; Fortunato et al. 2019).
There are numerous new compact pepper cultivars available that can be grown as potted, bedding, or garden plants (Halleck 2021). Most compact ornamental peppers produce pungent fruit of different shapes and colors (Dwyer 2021; Fortunato et al. 2019; Lillywhite et al. 2013; Stommel and Bosland 2007). Although pungent peppers are increasingly becoming popular among US consumers, they are frequently used as processed products (Lillywhite et al. 2013). In contrast, sweet peppers are frequently consumed fresh, but only a limited number of compact cultivars are available in the market to date. Regardless of type, compact pepper plants offer a space-saving advantage that can be particularly attractive to urban dwellers interested in gardening in small spaces such as windowsills, patios, or balconies (Conway 2016).
Increasing migration to urban areas with limited outdoor space has also spurred interest in indoor vegetable gardening (Min and Park 2018). However, few studies have been conducted in support of this increasingly popular gardening trend (Solis-Toapanta et al. 2020). Understanding the requirements to grow compact fruiting vegetables like pepper indoors is key to support the urban consumer (Cruz and Gómez 2022; Cruz et al. 2022) and could help advance existing efforts aiming to increase the availability of plants grown by the commercial indoor farming industry (Kwon 2022).
Similar to other solanaceous (Solanaceae) crops, some pepper cultivars are susceptible to intumescence when grown indoors in environments lacking ultraviolet radiation (100 to 400 nm) (Massa et al. 2008; Savvas et al. 2008; Spencer et al. 2019). Intumescence is a physiological disorder that causes hypertrophic lesions on the leaves and stems of plants and can reduce their aesthetic quality (Craver et al. 2014), possibly affecting gardening experiences (Conway 2016). Most studies on intumescence have evaluated the disorder on tomato seedlings (Eguchi et al. 2016a, 2016b; Kubota et al. 2017; Retana-Cordero et al. 2022; Suzuki et al. 2020). Therefore, limited information exists about the susceptibility of pepper plants to this disorder and its potential effect on fruit yield.
The objective of this study was to compare growth and productivity of 14 compact pepper cultivars grown in two environments. A greenhouse was used to evaluate plant responses under sunlight and in a fluctuating climate, close to outdoor gardening conditions. An indoor growth room was used as a proxy to a residential space with a constant daily light integral (DLI), and moderate temperature and relative humidity (RH). We also aimed to compare intumescence susceptibility among the different cultivars. We hypothesized that growth and productivity would be higher in the greenhouse because plants would be exposed to environmental conditions that promote active growth (e.g., warmer temperatures and higher DLIs). We also hypothesized that the lack of ultraviolet radiation indoors would be conducive to intumescence injury but that levels of susceptibility would vary among cultivars.
Two experimental runs were conducted in this study. In the first and second runs, seeds were sown on 14 Jan 2020 and 5 Sep 2020, respectively. Table 1 lists all cultivars evaluated in this study, with their corresponding abbreviation used hereafter. All seeds were sown into individual partial plug trays (55 mL individual cell volume) divided into 5 × 5-cell sections filled with horticultural grade substrate composed of (v/v) 79% to 87% peatmoss, 10% to 14% perlite, and 3% to 7% vermiculite (Pro-Mix BX general purpose; Premier Tech Horticulture, Quakertown, PA, USA). Seedlings were propagated in a passively ventilated polycarbonate greenhouse with retractable shade curtains in Gainesville, FL, USA. In the first experimental run, seedlings were grown under supplemental lighting delivered by 430-W high-pressure sodium lamps (P.L. Light Systems Inc., Beamsville, ON, Canada) used for 12 h·d−1 (0700 to 1900 HR). Seedlings in both experimental runs were fertigated as needed with a 15N–2.2P–12.5 fertilizer solution (Peter’s Professional K; ICL Specialty Fertilizers, Summerville, SC, USA) providing (mg·L−1) 100 nitrogen (N), 15 phosphorus (P), 83 potassium (K), 13 magnesium (Mg), 33 calcium (Ca), 0.50 iron (Fe), 0.25 manganese (Mn), 0.12 boron (B), 0.12 copper (Cu), 0.05 molybdenum (Mo), and 0.25 zinc (Zn). A weather station (Watchdog 2400 Mini Station; Spectrum Technologies Inc., Aurora, IL, USA) and datalogger (HOBO Micro Station; Onset Computer Corp., Bourne, MA, USA) were used in the first and second experimental runs, respectively, to record ambient temperature, RH (second run only), and DLI. In the first experimental run, average daily temperature and DLI during propagation were (mean ± SD) 20 ± 2 °C and 12 ± 5 mol·m−2·d−1, respectively. In the second experimental run, average daily temperature, RH, and DLI during propagation were 24 ± 3 °C, 87% ± 12%, and 12 ± 4 mol·m−2·d−1, respectively.
Sixteen uniform seedlings of all cultivars were individually transplanted into 8-inch diameter “azalea” plastic containers filled with the same substrate described above. Transplanting took place on 25 Feb and 28 Oct 2020 in the first and second experimental runs, respectively. A 1-inch layer of parboiled rice hulls (Sun Gro Horticulture, Agawam, MA, USA) was applied to the substrate surface of each container to minimize complications with fungus gnats [Bradysia sp. (Cloyd et al. 2009)]. Periodical applications of biological control products such as nematodes (NemaShield®; BioWorks Inc., Victor, NY, USA) were used as preventative measures for pest control.
After transplanting, eight plants of each cultivar were moved to one of two environments, and each replicate plant was considered an experimental unit (n = 8). In the greenhouse, the experiment was arranged as a completely randomized design. Plants in the first experimental run were randomly placed on four 6-ft-wide × 25-ft-long metallic benches located in a passively ventilated polycarbonate-glazed greenhouse with unit heaters. In the second experimental run, plants were randomly placed on four 6-ft-wide × 15-ft-long metallic benches located in a polycarbonate-glazed greenhouse with unit heaters and pad-and-fan evaporative cooling. In both experimental runs, plants in the greenhouse were spaced 46 cm apart and fertigated as needed with drippers using the same fertilizer solution previously described, providing 150 mg·L−1 N. A single datalogger (HOBO Micro Station) was used in the first experimental run, placed at above-canopy height in a central bench within the experimental area. In the second experimental run, temperature and RH probes (HMP60-L; Campbell Scientific, Inc., Logan, UT, USA) and quantum sensors (SQ512; Apogee Instruments Inc., Logan, UT, USA) interfaced to a datalogger (CR1000 with AM16/32B multiplexer; Campbell Scientific, Inc.) were placed at above-canopy height in the center of each bench. Measurements were recorded at 60-min intervals. In the first and second experimental runs, respectively, average daily temperature, RH, and DLI in the greenhouse were 24 ± 5 °C and 22 ± 4 °C, 61% ± 19% and 64% ± 18%, and 14 ± 2 mol·m−2·d−1 and 11 ± 4 mol·m−2·d−1. The day and night temperature and DLI for both experimental runs are shown in Fig. 1.
Citation: HortTechnology 33, 3; 10.21273/HORTTECH05194-23
The experiment indoors was conducted in a 12-m2 air-conditioned growth room with two opposite shelving units. Each shelving unit had an upper and a lower compartment (36 inches cm height × 36 inches width × 144 inches length) lined with insulation foam at the bottom. The experiment was arranged as a randomized complete block design where each compartment was regarded as a block containing two replicate plants per cultivar spaced 30 cm apart.
Four broadband white light-emitting diode (LED) fixtures (RAY66 PhysioSpec IndoorTM; Fluence Bioengineering, Austin, TX, USA) were placed in each compartment to provide a DLI of 11 mol·m−2·d−1 (220 µmol·m−2·s−1; 14 h·d−1 photoperiod from 0900 to 2300 HR), selected based on results from a study evaluating growth and yield of compact tomato plants under different DLIs (Cruz and Gómez 2022). Before starting the experiment, a light map was generated using a spectroradiometer (SS-110; Apogee Instruments Inc.) placed at midcanopy height (46 cm from the compartment surface), with every fixture turned on to account for light pollution. To achieve the target photosynthetic photon flux density (PPFD), the light output was controlled with dimmers (Solunar, Fluence Bioengineering) connected to a backup battery (BE425M-LM; APCAPC, West Kingston, RI, USA).
The growth room was kept at a constant ambient temperature of 21 ± 2 °C. Near-canopy air temperature and RH were monitored hourly with shielded dataloggers (RS-4HC; Elitech Technology, Inc., Milpitas, CA, USA) placed in the middle of each compartment. In the first and second experimental runs, average daily temperature and RH in the growth room were 22 ± 1 °C and 22 ± 2 °C and 66% ± 17% and 61% ± 10%, respectively. The day and night temperature and DLI for both experimental runs are shown in Fig. 1.
In both experimental runs, plants were fertigated as needed with the same fertilizer solution already described, providing 150 mg·L−1 N. Plants were hand-watered in the first run, whereas drip irrigation connected to a fertilizer injector was used as needed in the second run. Once flowering started in both experimental runs, plants were manually pollinated using a vibrating wand (Garden Pollinators VBP-01; VegiBee, Maryland Heights, MO, USA) every other day from 1100 to 1300 HR.
In both experimental runs, plant height, longest canopy width (from the endpoints of the two most distal leaves), and canopy width perpendicular to the longest width were recorded 5 weeks after transplanting to calculate growth index using the formula π × h × r2, where h is plant height, and r is calculated by multiplying ½ times the mean of two canopy widths. This was immediately followed by a visual assessment of intumescence using a subjective 0 to 3 scale, where 0 = no intumescence injury; 1 = less than 50% of the total leaves showed symptoms; 2 = more than 50% of the total leaves showed symptoms; and 3 = nearly all the leaves showed symptoms.
The first experimental run was prematurely ended on 2 Apr 2020 (6 weeks after transplanting) due to a university closure in response to the COVID-19 pandemic. Therefore, days to first harvest, total number of fruit, and total fruit fresh weight (FW) were only recorded for plants grown in the second experimental run. The date of the first harvest was recorded when at least one fruit per plant was fully mature, which was determined based on a full transition to the fruit color described on Table 1. After that initial harvest, the number of mature fruit and fruit FW were recorded biweekly. In addition, during the experimental termination on 23 Feb 2021 (∼17 weeks after transplanting), the number and FW of mature and immature fruit were recorded for all plants to calculate the total number of fruit and total fruit FW, respectively. Shoots were severed at the substrate surface and shoot dry weight was recorded after drying shoots in a forced-air oven at 70 °C for 4 d. Canopy density was calculated by dividing the shoot dry weight by plant height based on Faust et al. (2005).
Growth data were pooled for plants grown in both experimental runs, as the variances between experiments were not different, and the statistical interactions between cultivar and experimental run were not significant (P ≥ 0.05). Intumescence severity for each experimental run is presented separately (n = 8) because of the significant experimental run × cultivar interaction (P ≤ 0.05). Intumescence data are only presented for indoor-grown plants because of the lack of susceptibility observed in greenhouse-grown plants. Generalized linear mixed model procedures implemented in SAS® PROC GLIMMIX (SAS/STAT ver. 15.1; SAS Institute Inc., Cary, NC, USA) were used to determine differences among cultivars within each growing environment. A paired t test was then used to assess differences between plants of the same cultivar grown in the greenhouse compared with indoors for all variables except intumescence severity. Quantitative continuous response variables (growth index, canopy density, and total fruit FW) were treated as normally distributed, whereas count variables (days to first harvest, total number of fruit, and intumescence severity) were modeled through the Poisson distribution. A negative binomial transformation was used when the underlying assumption for the Poisson distribution (variance = mean) was not valid (= overdispersion) for a specific variable. Canopy density was modeled through a lognormal distribution. For each variable, the experiment and environment × cultivar interactions were calculated using the LSMEANS statement, which were then compared using the SLICEDIFF option. Cultivars were compared within each environment, and environments were compared within each cultivar. No adjustments for multiplicity were made to the calculated probability values, as this was an exploratory/screening experiment (Milliken and Johnson 2009; Saville 2015). A linear regression was applied to the quantitative response of total fruit FW to the increasing growth index using a statistical analysis software (R ver. 3.6.2; R Foundation for Statistical Computing, Vienna, Austria).
Overall, greenhouse-grown pepper plants were larger and produced a higher yield (fruit number and FW) than those grown indoors (Table 2, Fig. 2). For example, except for CO, growth index for plants in the greenhouse was 100% to 250% higher than that for those grown indoors. Similarly, total fruit FW (mature and immature fruit) was up to 621% higher in the greenhouse than indoors, except for AE, AP, and CO. Although average DLI, temperature, and RH throughout the experiments were relatively similar between the greenhouse and indoor environments, there were large differences in daily environmental fluctuations for all these parameters (Fig. 1). For example, plants in the greenhouse were exposed to solar DLIs that ranged from 9 to 18 mol·m−2·d−1, and average daily temperatures of 19 to 27 °C during the two experimental runs. In contrast, indoor-grown plants were exposed to a constant DLI of 11 mol·m−2·d−1 from sole-source lighting and an ambient temperature of ∼22 °C. Greenhouse plants were also exposed to large differences between day and night temperatures (DIF), which are known to affect plant height (Davies et al. 2002; Xiong et al. 2002). Additionally, plants in the greenhouse grew under a changing daily spectral composition from sunlight, with a far-red enriched environment in the early morning and late afternoon (Kotilainen et al. 2020). In contrast, plants indoors grew under broadband white LED fixtures with a fixed spectrum that lacked far-red radiation. Xiong et al. (2002) showed that applying end-of-day far-red radiation and providing a positive temperature DIF increases stem height of vegetable plants. The combined effects of providing a slightly higher DLI, warmer average temperatures, positive DIF, and far-red radiation from sunlight likely contributed to the larger plant size and higher yield measured in plants grown in the greenhouse compared with indoors.
Citation: HortTechnology 33, 3; 10.21273/HORTTECH05194-23
The number of branches were generally similar between plants of the same cultivar grown in the two environments (Table 2). In the greenhouse, BOF produced four times more branches than CO, FBR, FBRI, and SY, all of which produced an average of nine branches per plant. Indoors, BOF produced three times more branches than SY, which produced six branches per plant. Regardless of environment, cultivars BOF, CA, PN, AP, CH, SJ, and HTR had a bush-type growth habit and produced more branches than cultivars with an upright growth habit such as FBRI, SY, and FBR (Table 1). Pepper plants with numerous branches such as BOF have a higher ornamental value than those with an upright growth habit, which further increases as the number of flowers per branch increases (Stommel and Bosland 2007). More branches tend to also result in a larger number of fruit produced per plant, further increasing the attractiveness of pepper cultivars.
Canopy density, which integrates plant height and shoot dry weight, was 30% to 67% higher in AE, FBR, FBRI, HB, HTR, SJ, and SY plants grown indoors than in the greenhouse (Table 2). These plants had more foliage per unit area and, thus, could be considered as being of higher quality when grown indoors (Faust 2002; Townsley-Brascamp and Marr 1995). For example, dense foliage that covers the surface substrate in containers is a highly desirable trait among consumers (do Nascimento Costa et al. 2019). In the greenhouse, canopy density was highest for BOF (1.6 g·cm−1) and lowest for SJ (0.7 g·cm−1). Indoors, canopy density was highest for HTR (1.6 g·cm−1) and lowest for YT (0.8 g·cm−1). The only cultivar with a similar canopy density in the two environments was CO (0.08 g·cm−1), illustrating a lack of response to the different environments. This is also reflected in the similar growth index of CO in both environments (0.01 m3).
There were no differences in the number of days until first harvest between plants grown in the greenhouse and indoors, likely because flowering was induced during the propagation phase that took place in a common greenhouse compartment (Table 2). However, it was interesting to note that early-flowering cultivars such as CO and YT (data not shown) were not always the first to be harvested. In the greenhouse, AE, CH, FBR, PN, and SJ were harvested between 82 to 85 d after transplanting, while BOF, CO, FBRI, HB, HTR, SY, and YT took between 88 to 90 d to be harvested. Indoors, AP, PN, and SJ were first harvested 80 to 83 d after transplanting, whereas CA, CO, FBRI, HB, HTR, SY, and YT were harvested 88 and 90 d after transplanting. Other reports indicate that pepper fruit are typically harvested ∼90 d after transplanting, which corresponds with our findings and suggests that these compact cultivars do not enable earlier harvests compared with other larger-sized cultivars (Ashilenje 2013). Time to harvest could be a critical consideration when selecting edible pepper cultivars because the process can take significantly longer compared with other plant species. For example, in a cultivar evaluation with 20 compact tomato plants, Cruz et al. (2022) found that the first harvests occurred between 47 to 62 d after transplanting. Shortening the time for fruit to develop and ripen could also be a desirable trait for commercial production of compact pepper plants because this enables rapid cycling (Kwon 2022).
Except for SY, the total number of fruit was 34% to 865% higher in the greenhouse than indoors, and this trend was generally the same for total fruit FW (Table 2). In both environments, AP produced the highest number of fruit (378 in the greenhouse and 242 indoors). In contrast, the lowest number of fruit in the greenhouse were produced by FBRI and SY (22 and 21 fruit, respectively). Both of these cultivars produce edible sweet peppers, which are generally larger than those produced by the pungent pepper plants evaluated in this study. This difference in fruit size explains why the total fruit FW of FBRI and SY plants in the greenhouse were among the highest (695 g for FBRI and 646 g for SY). Similarly, although SY plants only produced 17 fruit per plant indoors, their fruit FW was the highest (483 g), likely due to its large fruit size (∼29 g per fruit). FBRI and YT produced the lowest number of fruit indoors (eight and six fruit, respectively). On the basis of the individual fruit FW estimated by dividing total fruit FW by total fruit number, plants grown indoors produced slightly larger fruit than those in the greenhouse.
In both environments, CO produced one of the lowest total fruit FW (106 and 61 g in the greenhouse and indoors, respectively). Similarly, PN and YT produced a lower total fruit FW (59 and 52 g, respectively) than other plants grown indoors, suggesting that these three cultivars have a limited yield for indoor gardening. Although minimum yields to satisfy home gardeners are unknown, increasing the number of fruit produced per plant is likely a more important trait than maximizing total fruit FW because consumers are more likely to maintain an interest in gardening when continuously harvesting fruit.
The number of fruit and overall yield were expected to be higher in the greenhouse than indoors, as it is widely known that higher DLIs and warmer temperatures promote pepper fruit yield (Heuvelink and Dorais 2005) (Figs. 1 and 2). Bakker and van Uffelen (1988) reported that the highest number of pepper fruit was obtained under an average daily temperature of 21 °C compared with average temperatures between 16 and 19 °C, or above 23 °C. The authors also reported that DIF had a limited effect on plant height, but a positive DIF increased yield (number of fruit and fruit FW), likely due to the stimulating effect that lower night temperatures have on flowering (Bakker and van Uffelen 1988). In addition, because plants in the greenhouse were larger than those indoors, they also required more frequent fertigation, which increased water availability and affected water and nutrient uptake, plausibly contributing to the differences in fruit yield measured in our study between greenhouse- and indoor-grown plants (Silber et al. 2003; Valiente-Banuet and Gutiérrez-Ochoa 2016).
Cultivars CA, CH, HTR, PN, SJ, and SY were affected by intumescence when grown indoors but the disorder was not observed when plants were grown in the greenhouse, which had ∼26% to 34% ultraviolet transmittance, based on spectral readings (Table 3). It is likely that the daily dose of ultraviolet radiation that greenhouse-grown plants received was sufficient to mitigate the disorder (Kubota et al. 2017). Indoors, lesions were mainly present on the abaxial surface of leaves, which corresponds with the findings of Bosland and Votava (2012) (Fig. 3). Chaudhari and Hedau (2020) reported that intumescence incidence decreased as pepper plants grew and produced new leaves, which corresponds with our observations and suggests that a developmental factor is associated with the disorder. Similar results were reported by Cruz et al. (2022) and Retana-Cordero et al. (2022) in tomato.
Citation: HortTechnology 33, 3; 10.21273/HORTTECH05194-23
Although our findings show that total fruit FW was lower in plants of all susceptible cultivars grown indoors compared with the greenhouse (Tables 2 and 3), it is unclear if intumescence had an effect on plant productivity, as yield differences were likely driven primarily by climatic and cultural practice differences in the two environments. Massa et al. (2008) showed that although photosynthesis was lower on pepper plants affected by intumescence, fruit set was unaffected. Further studies should compare productivity of susceptible plants under conditions that can induce and mitigate the disorder to provide insight about its effect on fruit yield.
Plants in the greenhouse were generally larger in size and produced a greater fruit yield than those grown indoors. All cultivars evaluated in this study are recommended for container gardening under sunlight, as their growth and yield are likely to satisfy the average home gardener. Similarly, all pepper cultivars are likely suitable for indoor gardening due to their compact size, but CO, PN, and YT produced the lowest total fruit fresh weight per plant and thus, should not be recommended to consumers aiming to maximize fruit yield. Cultivars CA, CH, HTR, PN, SJ, and SY were affected by intumescence, which could negatively affect indoor gardening experiences until recommendations to mitigate the disorder become available for small-scale gardening applications. Considering that the highest-yielding cultivars in both environments were generally the largest plants, home gardeners aiming to maximize yield should produce the largest cultivar that can fit within their designated growing space.
Average daily light integral (DLI) and temperature of the greenhouse (red) and indoor (blue) environments used in two experimental runs evaluating compact pepper plants for container gardening. In the temperature graphs, solid and dashed lines indicate average data collected during the day and night, respectively; (1.8 × °C) + 32 = °F.
Effect of growth index on total fruit fresh weight per plant produced by compact pepper cultivars grown in a greenhouse (A) or indoors (B). Growth index was calculated using the formula π × h × r2, where h is plant height and r is calculated by multiplying ½ times the mean of two canopy widths. Cultivar names are detailed in Table 1; 1 m3 = 35.3147 ft3, 1 g = 0.0353 oz.
Intumescence on abaxial leaf surface of ‘Spicy Jane’ pepper.
Contributor Notes
Financial support was received from the US Department of Agriculture (USDA) National Institute of Food and Agriculture, Multistate Research Project NE1835: Resource Optimization in Controlled Environment Agriculture; the USDA-Agricultural Research Service Floriculture and Nursery Research Initiative #58-5082-8-012 “Resilient Plants”; and industry partners of the Research on Urban Gardening consortium, including PanAmerican Seed Co., Syngenta Flowers, BioWorks, and Scotts Miracle Gro Co. We also thank partners from the Floriculture Research Alliance at the University of Florida.
C.G. is the corresponding author. E-mail: cgomezva@purdue.edu.
Average daily light integral (DLI) and temperature of the greenhouse (red) and indoor (blue) environments used in two experimental runs evaluating compact pepper plants for container gardening. In the temperature graphs, solid and dashed lines indicate average data collected during the day and night, respectively; (1.8 × °C) + 32 = °F.
Effect of growth index on total fruit fresh weight per plant produced by compact pepper cultivars grown in a greenhouse (A) or indoors (B). Growth index was calculated using the formula π × h × r2, where h is plant height and r is calculated by multiplying ½ times the mean of two canopy widths. Cultivar names are detailed in Table 1; 1 m3 = 35.3147 ft3, 1 g = 0.0353 oz.
Intumescence on abaxial leaf surface of ‘Spicy Jane’ pepper.
