Growth, morphology and accumulation of flavonoid compounds in green-and purple-leaved sweet basil (Ocimum basilicum L.), lamb's lettuce (Valerianella locusta (L.) Laterr.) and garden rocket (Eruca sativa L.) grown in a greenhouse under natural day light supplemented with white, blue (440 nm) and red (660 nm) light-emitting diodes (LEDs), all at 130 µmol m -2 s -1 , were studied in winter time. Under white and red LED lights, fresh weights of above-ground parts of lamb's lettuce and garden rocket were the highest, whereas under blue light they were the lowest, in comparison to the control (natural light). For green-and purple-leaved basil no significant differences in biomass production were observed when different light spectra qualities were applied. Supplementation of daily light with blue light resulted in more compact growth of green-leaved basil, as compared to plants grown under natural light and those supplemented with white and red lights. A non-destructive method using an optical sensor was used for evaluation of flavonol, anthocyanin and chlorophyll indexes in plants. Blue light led to significantly increased flavonol index in both green-and purple-leaved basil, lamb's lettuce and garden rocket plants.

A multiparametric optical sensor was used to nondestructively estimate phytochemical compounds in white cabbage leaves directly in the field. An experimental site of 1980 white cabbages (Brassica oleracea L. var. capitata subvar. alba), under different nitrogen (N) treatments, was mapped by measuring leaf transmittance and chlorophyll fluorescence screening in one leaf/cabbage head. The provided indices of flavonols (FLAV) and chlorophyll (CHL) displayed the opposite response to applied N rates, decreasing and increasing, respectively. The combined nitrogen balance index (NBI = CHL/FLAV) calculated was able to discriminate all of the plots under four N regimens (0, 100, 200, and 400 kg/ha) and was correlated with the leaf N content determined destructively. CHL and FLAV were properly calibrated against chlorophyll (R(2) = 0.945) and flavonol (R(2) = 0.932) leaf contents, respectively, by using a homographic fit function. The proposed optical sensing of cabbage crops can be used to estimate the N status of plants and perform precision fertilization to maintain acceptable crop yield levels and, additionally, to rapidly detect health-promoting flavonol antioxidants in Brassica plants.

Tetraploids of daylily have taken a leading position among the daylily cultivars due to desirable traits such as vigorous growth and flowers with more intense colour. In our previous studies, several tetraploids of daylily cultivars 'Blink of an Eye' and 'Berlin Multi' were obtained using in vitro techniques with different antimitotic agents (colchicine, oryzalin, trifluralin, and amiprophos methyl). The purposes of this study were to evaluate changes in daylily tetraploids in relation to their diploid counterparts and to assess variation among diploids and tetraploids derived from genetically homogenous plant material treated with antimitotic agents. In the first year of the ex vitro cultivation, growth of tetraploids was poorer in comparison with diploids, but in the second year, tetraploid growth was much more vigorous. Compared to diploids, in tetraploids of both cultivars percentage of flowering plants was lower, flowering was delayed by 8 days and 1 month in 'Blink of an Eye' and 'Berlin Multi', respectively, and bud number per scape was lower by approximately 20 and 40 %, respectively. Tetraploid leaves and flowers of both cultivars were significantly larger, chlorophyll concentration index was higher by approximately 40 %, and stomata were longer by 35 %. In 'Berlin Multi' tetraploids, inflorescence stems were shorter by 20 %. In 'Blink of an Eye', variation in flower colour tone and shape and stamen malformation rate was detected both within the unconverted diploids and tetraploids but was more evident in tetraploids. In both cultivars, variation was also found in the nuclear DNA content, which ranged in diploids and tetraploids, respectively, 8.02-8.53 and 16.01-17.13 pg in 'Berlin Multi ' and 8.28-8.71 and 15.93-17.36 pg in 'Blink of an Eye'. Since the variation, while less evident, also occurred in the diploids (regenerated from the antimitotic treated material), we suppose that these variations could be due to antimitotic agents that can induce not only chromosome doubling but also chromosomal and gene mutations. The extent and character of these changes can be related to parental genotype and/or antimitotic agent. Further research is required at the cytological and molecular level to explain the character of changes, epigenetic and/or genetic.

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.

BACKGROUND Accumulation and stability of tomato lycopene markedly depends on the cultivar, plant growing and storage conditions. To estimate lycopene in open‐field cultivated processing and fresh market tomatoes, we used a calibrated spectral reflectance portable sensor. RESULTS Lycopene accumulation in fruits attached to the plant, starting from the Green ripening stage, followed a sigmoidal function. It was faster and reached higher levels in processing (cv. Calista) than fresh market (cv. Volna) tomatoes (90 and 62 mg kg−1 fresh weight, respectively). During storage at 12, 20 and 25 °C, Red tomatoes retained about 90% of harvest lycopene for three weeks. Pink tomatoes increased lycopene during the first week of storage, but never reached the lycopene values of Red tomatoes ripened on the vine. Storability at 12 °C retaining the highest quality in red tomatoes was limited to 14 and 7 days for Calista and Volna cultivars, respectively. CONCLUSION Significant differences in lycopene accumulation and stability between processing and fresh market tomatoes were established by examining with time the very same fruits by a non‐destructive optical tool. It can be useful in agronomical and post‐harvest physiological studies and can be of interest for producers oriented to the niche nutraceutical market. © 2018 Society of Chemical Industry