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.

The aim of this study was to analyse the effect of regulated deficit irrigation (RDI) on growth and development of potted rhododendron ‘Catawbiense Boursault’ and ‘Old Port’ plants and to evaluate the usefulness of this technique for saving water in nursery production and promoting flowering. Plants were grown in 1.9 litre plastic containers in unheated greenhouse and were subjected to six irrigation treatments lasting for 14 weeks from June to mid-September. A drip irrigation system with one 2 dm3·h-1 emitter per container was used. Six treatments of irrigation were applied: T1) 1 ETp (evapotranspiration) (control, well watered plants); T2) 0.75 ETp (moderate deficit irrigation); T3) 0.5 ETp (strong deficit irrigation) during the entire period of the experiment and the others three were: T4) 1 ETp for 5 weeks followed by 0.5 ETp for 4 weeks and 1 ETp for 5 weeks (strong deficit irrigation in phase II); T5) 1 ETp for 5 weeks followed by 0.25 ETp for 4 weeks and 1 ETp for 5 weeks (very strong deficit irrigation in phase II) and T6) 0.5 ETp for 5 weeks followed by 1 ETp for 4 weeks and 0.5 ETp for 5 weeks (strong deficit irrigation in phases I and III and well watered plants in phase II). The results showed that exposing plants to moderate water deficit (0.75 ETp) for 14 weeks had the best effect on quality of Rhododendron ‘Old Port’ plants. In this cultivar the application of very strong water deficit (0.25 ETp) for 4 weeks during floral buds initiation improved significantly floral bud set. Reduction of water supply by 50% during 14 weeks of Rhododendron ‘Catawbiense Boursault’ cultivation resulted in both the enhanced plant quality and increased number of floral buds set. Rhododendrons has adapted to reduced water supplies through stomatal control. At the end of the experiment, chlorophyll fluorescence parameter Fv/Fm (quantum efficiency of photosystem II) did not indicate damage to photosynthetic apparatus and relative chlorophyll content in leaves of plants subjected to all irrigation regimes did not differ significantly between each other.

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.

The aim of the study was to develop an efficient micropropagation system for Rosa ‘Konstancin’, an interspecific hybrid between R. rugosa and R. beggeriana, whose fruits have high pro-health value. Shoot cultures were initiated from shoot buds collected in May and August from 15-year-old field-grown Rosa ‘Konstancin’ shrubs. The effect and interaction of different concentrations of phytohormones, sucrose and iron sources on in vitro initiation, multiplication and rooting of shoots were studied. The time of collecting explants from donor plants significantly affected the initiation of shoot culture of Rosa ‘Konstancin’. Considerably higher frequency of bud break (100%) was obtained in explants isolated in August as compared to those collected at the end of May (30%). All buds developed into single shoots after 2-4 weeks of growing on the basal Murashige and Skoog medium containing 2.2 µM BAP, 0.3 µM GA3 and 88 mM of sucrose. The highest multiplication rate (4.8 shoots/explant) in a 5-week period was obtained on MS medium containing 50% of nitrogen salts, 3.1 µM BAP, 0.9 µM GA3 and 58 mM sucrose. High rooting frequency (100%) and quality of rooted plantlets was obtained on a medium containing 0.5 µM IBA, 138 µM Fe-EDDHA and 88 mM sucrose. Fe-EDDHA had a beneficial effect on the growth and photosynthetic activity of Rosa ‘Konstancin’ plantlets, which were successfully acclimatized ex vitro, with a more than 90% survival rate.

Among the fungal diseases of apple trees, serious yield losses are due to an apple scab caused by Venturia inaequalis. Protection against this disease is based mainly on chemical treatments, which are currently very limited. Therefore, it is extremely important to introduce cultivars with reduced susceptibility to this pathogen. One of the important sources of variability for breeding is the process of polyploidization. Newly obtained polyploids may acquire new features, including increased resistance to diseases. In our earlier studies, numerous tetraploids have been obtained for several apple cultivars with ‘Free Redstar’ tetraploids manifesting enhanced resistance to apple scab. In the present study, tetraploids of ‘Free Redstar’ were assessed in terms of phenotype and genotype with particular emphasis on the genetic background of their increased resistance to apple scab. Compared to diploid plants, tetraploids (own-rooted plants) were characterized with poor growth, especially during first growing season. They had considerably shorter shoots, fewer branches, smaller stem diameter, and reshaped leaves. In contrast to own-rooted plants, in M9-grafted three-year old trees, no significant differences between diplo- and tetraploids were observed, either in morphological or physiological parameters, with the exceptions of the increased leaf thickness and chlorophyll content recorded in tetraploids. Significant differences between sibling tetraploid clones were recorded, particularly in leaf shape and some physiological parameters. The amplified fragment length polymorphism (AFLP) analysis confirmed genetic polymorphism of tetraploid clones. Methylation-sensitive amplification polymorphism (MSAP) analysis showed that the level of DNA methylation was twice as high in young tetraploid plants as in a diploid donor tree, which may explain the weaker vigour of neotetraploids in the early period of their growth in the juvenile phase. Molecular analysis showed that ‘Free Redstar’ cultivar and their tetraploids bear six Rvi genes (Rvi5, Rvi6, Rvi8, Rvi11, Rvi14 and Rvi17). Transcriptome analysis confirmed enhanced resistance to apple scab of ‘Free Redstar’ tetraploids since the expression levels of genes related to resistance were strongly enhanced in tetraploids compared to their diploid counterparts.