Abstract
In this study, the effect of different photosynthetic photon flux density (PPFD) provided by LEDs (Light Emitting Diodes) and photoperiod on biomass production, morphological traits, photosynthetic performance, sensory attributes, and image texture parameters of indoor cultivated romaine lettuce was evaluated. Two cultivars of lettuce Lactuca sativa var. longifolium namely ‘Casual’ (Syngenta)—midi romaine lettuce with medium-compact heads—and ‘Elizium’ (Enza Zaden)—a mini type (Little Gem) with compact heavy heads—were used. PPFD of 160 and 240 µmol m−2 s−1 and photoperiod of 16 and 20 h were applied, and Daily Light Integral (DLI) values were 9.2, 11.5, 13.8, and 17.3 mol m−2 day−1. The experiment lasted 30 days in the Indoor Controlled Environment Agriculture facility. DLI equal to 17.3 mol m−2 per day for cv. ‘Casual’ and 11.5–17.3 mol m−2 per day for cv. ‘Elizium’ allowed to obtain a very high fresh weight, 350 and 240 g, respectively, within 30 days of cultivation in an indoor plant production facility. The application of the lowest PPFD 160 µmol m−2 s−1 and 16 h photoperiod (9.2 mol m−2 per day DLI) resulted in the lowest fresh weight, the number of leaves and head circumference. The level of nitrate, even at the lowest DLI, was below the limit imposed by European Community Regulation. The cv. ‘Elizium’ lettuce grown at PPFD 240 µmol m−2 s−1 and 16 h photoperiod had the highest overall sensory quality. The cv. ‘Casual’ lettuce grown at PPFD 160 µmol m−2 s−1 and 20 h photoperiod had the lowest sensory quality. The samples subjected to different photoperiod and PPFD were also successively distinguished in an objective and non-destructive way using image features and machine learning algorithms. The average accuracy for the leaf samples of cv. ‘Casual’ lettuce reached 98.75% and for cv. ‘Elizium’ cultivar—86.25%. The obtained relationship between DLI and yield, as well as the quality of romaine lettuce, can be used in practice to improve romaine lettuce production in an Indoor Controlled Environment.
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Claims 8
Claim · model-written summary
Casual at 17.3 daily light integral reached 350 g fresh weight.
- Taxon
- Romaine Lettuce
Lactuca sativa var. longifoliat0 - Material
- ‘Casual’e0
- Treatment
- 17.3 mol m−2 per daye0
- Outcome
- fresh weighte0
- Value
- 350e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DLI equal to 17.3 mol m−2 per day for cv. ‘Casual’ and 11.5–17.3 mol m−2 per day for cv. ‘Elizium’ allowed to obtain a very high fresh weight, 350 and 240 g, respectively”
t0“Romaine Lettuce”
Claim · model-written summary
Elizium at 11.5–17.3 daily light integral reached 240 g fresh weight.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Material
- ‘Elizium’e0
- Treatment
- 11.5–17.3 mol m−2 per daye0
- Outcome
- fresh weighte0
- Value
- 240 ge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DLI equal to 17.3 mol m−2 per day for cv. ‘Casual’ and 11.5–17.3 mol m−2 per day for cv. ‘Elizium’ allowed to obtain a very high fresh weight, 350 and 240 g, respectively”
t0“Romaine Lettuce”
Claim · model-written summary
The lowest light treatment produced the lowest fresh weight, leaf count and head circumference.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Treatment
- PPFD 160 µmol m−2 s−1 and 16 h photoperiode0
- Outcome
- fresh weight, the number of leaves and head circumferencee0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The application of the lowest PPFD 160 µmol m−2 s−1 and 16 h photoperiod (9.2 mol m−2 per day DLI) resulted in the lowest fresh weight, the number of leaves and head circumference”
t0“Romaine Lettuce”
Claim · model-written summary
Nitrate remained below the regulatory limit even at the lowest daily light integral.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Outcome
- level of nitratee0
- Direction
- belowe0
- Comparator
- limit imposed by European Community Regulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The level of nitrate, even at the lowest DLI, was below the limit imposed by European Community Regulation”
t0“Romaine Lettuce”
Claim · model-written summary
Elizium at 240 PPFD and 16 hours had the highest sensory quality.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Material
- ‘Elizium’e0
- Treatment
- PPFD 240 µmol m−2 s−1 and 16 h photoperiode0
- Outcome
- overall sensory qualitye0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The cv. ‘Elizium’ lettuce grown at PPFD 240 µmol m−2 s−1 and 16 h photoperiod had the highest overall sensory quality”
t0“Romaine Lettuce”
Claim · model-written summary
Casual at 160 PPFD and 20 hours had the lowest sensory quality.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Material
- ‘Casual’e0
- Treatment
- PPFD 160 µmol m−2 s−1 and 20 h photoperiode0
- Outcome
- sensory qualitye0
- Direction
- loweste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The cv. ‘Casual’ lettuce grown at PPFD 160 µmol m−2 s−1 and 20 h photoperiod had the lowest sensory quality”
t0“Romaine Lettuce”
Claim · model-written summary
Image features and machine learning distinguished light treatments with 98.75% accuracy for Casual.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Material
- ‘Casual’e0
- Outcome
- average accuracye0
- Value
- 98.75%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The samples subjected to different photoperiod and PPFD were also successively distinguished in an objective and non-destructive way using image features and machine learning algorithms. The average accuracy for the leaf samples of cv. ‘Casual’ lettuce reached 98.75%”
t0“Romaine Lettuce”
Claim · model-written summary
Image features and machine learning reached 86.25% accuracy for Elizium.
- Taxon
- Romaine LettuceLactuca sativa var. longifoliat0
- Material
- ‘Elizium’e0
- Outcome
- average accuracye0
- Value
- 86.25%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The average accuracy for the leaf samples of cv. ‘Casual’ lettuce reached 98.75% and for cv. ‘Elizium’ cultivar—86.25%”
t0“Romaine Lettuce”
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