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Abstract Background Micro-propagation is the primary technique for the mass propagation of greenhouse orchids. However, various factors, including culture media and cultivation systems, influence the scaling-up and efficient commercialization of in vitro techniques. The utilization of liquid cultivation systems and bioreactors are relatively cost-effective and has attracted significant attention for mass production. In this study, we evaluated the effects of eight culture media, in both semi-solid and liquid forms, on the growth of in vitro mini-plantlets of Phalaenopsis orchids. We subsequently assessed the performance of four selected media: half-strength modified Murashige and Skoog (1/2 MMS), modified FAST (MFAST), and two simplified media (SM1 and SM2), across four types of cultivation systems, including semi-solid media in glass jars, liquid media in a permanent immersion system using Erlenmeyer flasks on a shaker (PIS), and a temporary immersion system (TIS) in two forms: FA-Bio bioreactor (TIS-FA-Bio) and RITA® bioreactor (TIS-RITA®). Results The results indicated that the optimal culture medium for orchid growth depends on the cultivation system used. Among the eight evaluated semi-solid and liquid media, the highest plant growth was observed in the SM2 medium, attributed to the presence of additives (banana powder and activated charcoal), two types of sugar (with high carbon content), and small amounts of nickel and ascorbic acid. The high carbon content in the SM2 liquid medium, combined with the temporary immersion explants in a large volume of medium in the TIS-RITA®, resulted in the highest total carbohydrate content and enhanced plant growth. The maximum quantum efficiency of photosystem II (Fv/Fm) and the number of plantlets per liter in SM2 semi-solid medium were higher than those in the 1/2 MMS semi-solid medium (control), leading to a 61.6% reduction in production costs. Furthermore, the number of plantlets per liter in the TIS-FA-Bio containing SM2 (10.8 USD) was higher than in TIS-RITA® with 1/2 MMS (39.3 USD), resulting in a 72.5% decrease in production costs due to a lower volume of medium and the use of inexpensive equipment. Conclusions We recommend the use of SM2 in TIS-FA-Bio and TIS-RITA® for economical and efficient mass propagation of Phalaenopsis orchid.

Abstract Horticulture in controlled environments has been increasingly used to tackle limitations on crop production. As a crucial environmental factor, light regulate plant growth and metabolism. In the present study, basil plants were subjected to different light durations and intensities considering constant daily light integral (DLI). The lighting environment included 200, 300, and 400 µmol m− 2 s− 1 intensities for 18, 12, and 9 h, respectively. DLI amounted to 12.96 mol m− 2 d− 1 among all light treatments (LI200 for 18 h, LI300 for 12 h, and LI400 for 9 h). Half of the plants under each light treatment were exposed to 30 µmol m− 2 s− 1 of far-red light. The results indicated the general negative impact of LI400/9 on the growth of basils. Exposure to far-red light hurt the growth of the shoot, while it enhanced stem and petiole elongation. This effect was due to higher gibberellin accumulation, which resulted in shade avoidance responses. Exposure to far-red light also reduced anthocyanin and flavonoid contents, as two important nutritional components. Soluble carbohydrates increased, while storage carbohydrates decreased by increasing lighting duration/decreasing light intensity or by far-red light inclusion. The lowest antioxidant activity was detected in LI400/9. In the LI200/18, the highest level of auxin and the lowest level of cytokinin were detected, while the LI300/12 exhibited the highest level of gibberellin hormone. Low light intensity and long photoperiod enhanced plant biomass and phytochemical production and are recommended for basil production in controlled environments.

Abstract Little is known about the relative impact of lighting duration and light intensity on lettuce production, as well as whether daily light integrals (DLIs) play a significant role during different plant growth stages. Four DLIs were tested: 8.64, 11.52, 12.96, and 17.28 mol m−2 day−1 as supplemental lighting, which were obtained from a combination of supplemental light intensities at 200 and 300 µmol m−2 day−1 for 12 and 16 h. Sunlight was used as control. A direct correlation was observed between DLIs and yield, total fresh weight, and total dry weight. Under supplemental lighting, relative growth rate (RGR) increased due to an increase in net assimilation rate (NAR) rather than in leaf area ratio (LAR). Plants in the seedling stage were more sensitive to an elevation in DLI than in the head stage. This was confirmed by a greater increase in NAR compared to their corresponding control under the same DLI. Increasing DLI also improved lettuce quality via reducing nitrate and increasing protein content. Higher DLIs (12.96 and 17.28 mol m−2 day−1) led to a decrease in maximum quantum yield of photosystem II and an increase in performance index. In conclusion, manipulating RGR through NAR adjustments proved to be more effective than changes in LAR, and adjusting supplemental DLI at each stage was necessary to achieve a larger NAR and, consequently, a larger RGR.

In this study, the effectiveness of preharvest fertigation using calcium thiosulfate (CaTS) and potassium thiosulfate (KTS) to enhance the shelf life of bell peppers was investigated. The nutrient solution was enriched with KTS (either 0.26 or 0.53 mM of a commercial formulation) or CaTS (0.66 mM of a commercial formulation), and compared to a commercial source-based nutrient solution as a control. Fruit quality attributes and the activity of key enzymes involved in oxidative stress defense, enzymatic browning, cell wall degradation, and membrane lipid degradation were investigated for 30 days of storage. Results showed that CaTS and KTS treatments preserved protein (a secondary energy reserve) and proline content, and enhanced the fruit's PSII activity throughout storage. Despite increased phenylalanine ammonia-lyase activity, CaTS and KTS fertigation did not affect polyphenol oxidase activity. CaTS and KTS fertigation increased the activity of five (out of seven) antioxidant enzymes and impaired the activity of one (out of two) cell wall hydrolytic enzyme. CaTS was the most effective treatment, followed by KTS (0.53 mM), in causing these promotive effects. In conclusion, preharvest application of CaTS (0.66 mM) and KTS (0.53 mM) prolonged the postharvest life and delayed senescence of bell pepper fruits by preserving fruit weight, firmness, and photosynthetic performance, as well as enhancing the antioxidant defense system.

There are numerous challenges associated with the large-scale production of walnut In vitro-plantlets. It is imperative to develop new environmental control systems for its In vitro propagation. Additionally, there is a lack of knowledge regarding the impacts of lighting systems on the morpho-physiological traits and biomass accumulation in walnut tissue-cultured explants. In this study, walnut nodal shoots were subjected to eight different light spectra, including white, blue, red, green, far-red, blue-red combination, red-far-red combination, and a fluorescent lamp serving as a control, over a period of 28 days. The results indicated that combined spectra treatments, such as blue-red and red-far-red, led to improved biomass accumulation (total fresh and dry weight) compared to other monochromatic light spectral treatments. Furthermore, Light-emitting diode (LED) treatments had a discernible impact on the morpho-physiological traits of walnut In vitro-explants. Specifically, white light spectra enhanced Specific leaf area (SLA), while the green light spectra increased leaf water content (LWC) when compared to other light treatments. Additionally, the application of far-red light elevated leaf mass area (LMA) and water content per unit leaf area (LWCA). The findings of this study demonstrate that the quality, morphological, and growth characteristics of In vitro explants of walnut can be enhanced by utilizing specific light spectra.

Abstract During the seasons with limited light intensity, reductions in growth, yield, and quality are challenging for commercial cut rose production in greenhouses. Using artificial supplemental light is recommended for maintaining commercial production in regions with limited light intensity. Nowadays, replacing traditional lighting sources with LEDs attracted lots of attention. Since red (R) and blue (B) light spectra present the important wavelengths for photosynthesis and growth, in the present study, different ratios of supplemental R and B lights, including 90% R: B 10% (R90B10), 80% R: 20% B (R80B20), 70% R: 30% B (R70B30) with an intensity of 150 µmol m−2 s−1 together with natural light and without supplemental light (control) were applied on two commercial rose cultivars. According to the obtained results, supplemental light improved growth, carbohydrate levels, photosynthesis capacity, and yield compared to the control. R90B10 in both cultivars reduced the time required for flowering compared to the control treatment. R90B10 and R80B20 obtained the highest number of harvested flower stems in both cultivars. Chlorophyll and carotenoid levels were the highest under control. They had a higher ratio of B light, while carbohydrate and anthocyanin contents increased by having a high ratio of R light in the supplemental light. Analysis of chlorophyll fluorescence was indicative of better photosynthetic performance under a high ratio of R light in the supplemental light. In conclusion, the R90B10 light regime is recommended as a suitable supplemental light recipe to improve growth and photosynthesis, accelerate flowering, and improve the yield and quality of cut roses.

Controlled environment agriculture is a promising solution to address climate change and resource limitations. Light, the primary energy source driving photosynthesis and regulating plant growth, is critical in optimizing produce quality. However, the impact of specific light spectra during night interruption on improving phytochemical content and produce quality remains underexplored. This study investigated the effects of red (peak wavelength at 660 nm) and far-red night interruption (peak wavelength at 730 nm) on photosynthetic efficiency, biomass distribution, and phytochemical production in Italian basil (Ocimum basilicum L.). Treatments included red light, far-red light, a combination of both, and a control without night interruption. Red light significantly increased chlorophyll a by 16.8%, chlorophyll b by 20.6%, and carotenoids by 11%, improving photosynthetic efficiency and nutritional quality. Red light also elevated anthocyanin levels by 15.5%, while far-red light promoted flavonoid production by 43.56%. Although red light enhanced biomass, the primary benefit was improved leaf quality, with more biomass directed to leaves over roots. Far-red light reduced transpiration, enhancing post-harvest water retention and shelf life. These findings demonstrate that red and far-red night interruption can optimize phytochemical content, produce quality, and post-harvest durability, offering valuable insights for controlled environment agriculture. Future research should focus on refining night interruption light strategies across a broader range of crops to enhance produce quality and shelf life in controlled environment agriculture.

Purpose: The use of supplementary light in regions with low natural sunlight is necessary to fulfill the increasing consumer requests for fresh vegetables. This study aimed to investigate the effect of different combinations of red and blue LEDs on yield and quality of greenhouse-grown sweet pepper (Capsicum annuum L.) fruits during the growth period. Research method: The experiments were conducted in Rasht, Iran as split plots in the form of a completely randomized design in three repetitions (four plants per plot) on two cultivars of sweet pepper (Padra and Shadlin). With the appearance of the first flower buds, plants were exposed to different light treatments including: three combinations of red (R) and blue (B) LEDs (T1:R8B1, T2:R7B2, and T3:R6B3), with a same intensity of 200 μmolm-2s-1 as supplement light to the natural light, together with natural light as control treatment (CT). Sweet pepper fruits were harvested weekly over 27 weeks and fruit yield and quality were assessed. Findings: Supplemental light using LEDs significantly increased yield and fruit quality parameters (except titratable acidity and maturity index) compared to the control. Marketable yield was differed among the light treatments and plants exposed to T3 showed the highest marketable yield (14.58 kg/m2). The effect of supplemental light on total yield was more detectable when the average daily light integral was the lowest (for example, the difference between T3 and the control treatment in January was 1.27 kg/m2, while this difference was 0.68 kg/m2 in June). No significant difference was observed between cultivars and T3 was the best treatment in most parameters. Research limitations: No limitations were found. Originality/Value: In the northern regions of Iran, even in the months that do not seem to have light limitations, the use of supplementary light is recommended to increase the yield of sweet peppers in the greenhouse.

Ocimum basilicum L. is one of the most important medicinal and vegetable crops due to its essential oil, pleasant aroma and taste. In this study, we evaluated the impact of different light intensities, including 100 %, 50 %, and 30 % of natural sunlight, on the growth, phytochemical compositions, and antioxidant activity of green and purple basil cultivars at two different harvest times: early morning and noon. The height of the plant, number of leaves per plant, length of the petiole, diameter of the stem, and fresh and dry weight of the shoot were all reduced by decreasing light intensity in both basil cultivars. When the plants of both cultivars were grown under full light intensity and were sampled at noon, they showed the highest phenolic and flavonoid contents. The highest antioxidant activity was detected in purple basil cultivars grown under 30 and 50 % of sunlight in both harvests. The green basil cultivar showed the highest antioxidant activity when exposed to 30 % sunlight and harvested in the early morning. The highest essential oil content and yield in both basil cultivars were obtained under full sunlight in the early morning harvests. In summary, light intensity and harvest time influence the phytochemical yield, composition, and growth of two studied basil cultivars. Optimal results, particularly for medicinal purposes, were achieved by morning harvesting to maximize the essential oil yield of basils.

Iron (Fe) deficiency-induced chlorosis can be a serious problem in grapevine cultivation. Measuring genotypic tolerance to this disorder is of vital importance in rootstock selection. In this research, different sources of Fe (FeSO4·7H2O and FeEDTA) were used and their effects were evaluated on the response of a tolerant (‘Thompson Seedless’) and a sensitive (‘Flame Seedless’) grape cultivar. Also, their cross-grafted combinations [‘Flame Seedless’/’Thompson Seedless’ (FS/TS) and ‘Thompson Seedless’/‘Flame Seedless’ (TS/FS)] were evaluated for tolerance to Fe deficiency. Bicarbonate (30 mM) was used for inducing iron deficiency in the plants. Despite the negative effects of bicarbonate, the ‘Thompson Seedless’ maintained a significant chlorophyll index, compared to the ‘Flame Seedless’ cultivar. Gas exchange measurements showed that the bicarbonate had more adverse effects on photosynthesis and water-use-efficiency (WUE) in the ‘Flame Seedless’ cultivar. Despite the bicarbonate toxicity, the photosynthetic system of the FS/TS graft combination showed no significant change in FV/FO, whereas adverse effects occurred significantly in ‘Thompson Seedless’, ‘Flame Seedless’, and their TS/FS graft combination. Bicarbonate decreased the performance index in ‘Flame Seedless’. In conclusion, scions of the susceptible cultivar performed well when grafted on tolerant rootstocks. Such grafting combinations can help plants to cope with the negative effects of bicarbonate toxicity on grapevine.

During retail storage, potato tubers are exposed to light that results in tuber greening. Green tubers are toxic and rejected by consumers. In the present study, the effect of Citrashine® natural wax on the postharvest tuber greening of two potato cultivars (‘Mondial’ and ‘Sifra’) was studied. The tubers were irradiated with white light during a 12-day storage period at ambient temperature. During light exposure, tubers were evaluated for colour, pigmentation, chlorophyll fluorescence and starch granule distribution at 3-day intervals. The results showed that wax-treated tubers had significantly (p < 0.05) less green colour as represented by visual and objective colour parameters (a*, b*, C* and h°), compared to those treated with water (control). The pigmentation of the tubers was significantly influenced by the postharvest Citrashine® natural wax treatment. The total chlorophyll content was significantly lower in wax-treated tubers, while the carotenoid content was significantly higher in wax-treated tubers compared to their contents in control samples. Scanning electron microscopy showed that the starch granule size was normally distributed in wax-treated tubers compared to the untreated ones, which was negatively skewed. In conclusion, Citrashine® natural wax showed the potential to be a postharvest technology for controlling greening defects on potato tubers. The results provide a possible effective strategy for controlling the postharvest greening of potato tubers.

Gamma radiation has been suggested to have post-effects on emerging plants when applied to the seeds. In the present study, we aimed to induce alterations in photosynthetic functionality and subsequent modifications in secondary metabolites of summer savory following seed priming with gamma radiation. Savory seeds were treated with 0, 50, 100, 200, and 300 Gy gamma radiation in a completely randomized design with ten replications for morphological and photosynthetic parameters and three for phytochemical assessments. The results showed that gamma radiation on seeds adversely affected photosynthetic performance, especially at the highest doses. It negatively influenced the growth, while increasing the shoot branching, the number of nodes, and the diameter of the stem. Gamma radiation on seeds generally reduced pigmentation in savory leaves, such as chlorophylls, carotenoids, and anthocyanins. However, soluble sugar, starch, total phenolics, and total flavonoid contents were elevated in the leaves of plants that emerged from gamma-primed seeds. Gamma radiation priming reduced essential oil’s percentage and yield. Carvacrol and limonene components of essential oil were diminished, whereas linalool and thymol were increased. In conclusion, due to its inherent stress-inducing effects, and despite some positive effects on phytochemicals, seed priming with gamma radiation adversely influenced growth, photosynthesis, and quantity and quality of savory essential oils. Further research is still needed to target the use of gamma radiations before harvesting the seeds or determine the cytogenetic characteristics of irradiated plants.

The postharvest lighting environment is a main factor that influences quality preservation for harvested biomass. The objective of this study was to evaluate postharvest changes in bioactive compounds of lettuce with different storage light spectra. The effects of green LEDs with peaks at 500 nm and 530 nm, white LEDs (400-700 nm), and dark storage were evaluated, where light intensity (10 μmol m-2 s-1) and photoperiod (12 h per day) were constant with air temperature at 5°C over the 14 d treatment period. Lettuce stored with 500 nm and 530 nm green LEDs exhibited 1474.5% and 1451.8% (approximately 15.7 and 15.5 times) higher antioxidant activity, respectively, compared to dark storage. Significant improvements in total phenolic content, and 67.5% and 64.8% increases in total soluble solids with 530 nm and 500 nm green LEDs over dark storage were discerned. Exposure to 530 nm green LEDs led to 128.2% (approximately 2.28 times) higher anthocyanin content, a 26.2% increase in carotenoids, and a 95% rise in flavonoid content compared to dark storage. Increases of 26.4% and 16.0% in chlorophyll a content in lettuce stored under 500 nm and 530 nm green LEDs, respectively, and 65.6% and 46.6% rises in the Chlorophyll a/b ratio were observed. Compared to dark storage, green LEDs (500 nm) resulted in a 13.5% higher total chlorophyll content. Findings underscore the positive impact of green LEDs on the nutritional quality of lettuce, providing insight for postharvest practices.

Abstract Due to the photocatalytic property of titanium dioxide (TiO2), its application may be dependent on the growing light environment. In this study, radish plants were cultivated under four light intensities (75, 150, 300, and 600 μmol m−2 s−1 photosynthetic photon flux density, PPFD), and were weekly sprayed (three times in total) with TiO2 nanoparticles at different concentrations (0, 50, and 100 μmol L−1). Based on the obtained results, plants used two contrasting strategies depending on the growing PPFD. In the first strategy, as a result of exposure to high PPFD, plants limited their leaf area and send the biomass towards the underground parts to limit light-absorbing surface area, which was confirmed by thicker leaves (lower specific leaf area). TiO2 further improved the allocation of biomass to the underground parts when plants were exposed to higher PPFDs. In the second strategy, plants dissipated the absorbed light energy into the heat (NPQ) to protect the photosynthetic apparatus from high energy input due to carbohydrate and carotenoid accumulation as a result of exposure to higher PPFDs or TiO2 concentrations. TiO2 nanoparticle application up-regulated photosynthetic functionality under low, while down-regulated it under high PPFD. The best light use efficiency was noted at 300 m−2 s−1 PPFD, while TiO2 nanoparticle spray stimulated light use efficiency at 75 m−2 s−1 PPFD. In conclusion, TiO2 nanoparticle spray promotes plant growth and productivity, and this response is magnified as cultivation light intensity becomes limited.

In this study, we advance a robust methodology for identifying specific intelligence-related proteins across phyla. Our approach exploits a support vector machine-based classifier capable of predicting intelligence-related proteins based on a pool of meaningful protein features. For the sake of illustration of our proposed general method, we develop a novel computational two-layer predictor, Intell_Pred, to predict query sequences (proteins or transcripts) as intelligence-related or non-intelligence-related proteins or transcripts, subsequently classifying the former sequences into learning and memory-related classes. Based on a five-fold cross-validation and independent blind test, Intell_Pred obtained an average accuracy of 87.48 and 88.89, respectively. Our findings revealed that a score >0.75 (during prediction by Intell_Pred) is a well-grounded choice for predicting intelligence-related candidate proteins in most organisms across biological kingdoms. In particular, we assessed seismonastic movements and associate learning in plants and evaluated the proteins involved using Intell_Pred. Proteins related to seismonastic movement and associate learning showed high percentages of similarities with intelligence-related proteins. Our findings lead us to believe that Intell_Pred can help identify the intelligence-related proteins and their classes using a given protein/transcript sequence.

Light plays a crucial role in photosynthesis, which is an essential process for plantlets produced during in vitro tissue culture practices and ex vitro acclimatization. LED lights are an appropriate technology for in vitro lighting but their effect on propagation and photosynthesis under in vitro condition is not well understood. This study aimed to investigate the impact of different light spectra on growth, photosynthetic functionality, and stomatal characteristics of micropropagated shoots of Persian walnut (cv. Chandler). Tissue-cultured walnut nodal shoots were grown under different light qualities including white, blue, red, far-red, green, combination of red and blue (70:30), combination of red and far-red (70:30), and fluorescent light as the control. Results showed that the best growth and vegetative characteristics of in vitro explants of Persian walnut were achieved under combination of red and blue light. The biggest size of stomata was detected under white and blue lights. Red light stimulated stomatal closure, while stomatal opening was induced under blue and white lights. Although the red and far-red light spectra resulted in the formation of elongated explants with more lateral shoots and anthocyanin content, they significantly reduced the photosynthetic functionality. Highest soluble carbohydrate content and maximum quantum yield of photosystem II were detected in explants grown under blue and white light spectra. In conclusion, growing walnut explants under combination of red and blue lights leads to better growth, photosynthesis functionality, and the emergence of functional stomata in in vitro explants of Persian walnuts.

Abstract Identifying environmental factors that improve plant growth and development under nitrogen (N) constraint is essential for sustainable greenhouse production. In the present study, the role of light intensity and N concentrations on the biomass partitioning and physiology of chrysanthemum was investigated. Four light intensities [75, 150, 300, and 600 µmol m−2 s−1 photosynthetic photon flux density (PPFD)] and three N concentrations (5, 10, and 15 mM N L−1) were used. Vegetative and generative growth traits were improved by increase in PPFD and N concentration. High N supply reduced stomatal size and gs in plants under lowest PPFD. Under low PPFD, the share of biomass allocated to leaves and stem was higher than that of flower and roots while in plants grown under high PPFD, the share of biomass allocated to flower and root outweighed that of allocated to leaves and stem. As well, positive effects of high PPFD on chlorophyll content, photosynthesis, water use efficiency (WUE), Nitrogen use efficiency (NUE) were observed in N-deficient plants. Furthermore, photosynthetic functionality improved by raise in PPFD. In conclusion, high PPFD reduced the adverse effects of N deficiency by improving photosynthesis and stomatal functionality, NUE, WUE, and directing biomass partitioning toward the floral organs.

The agricultural sector faces challenges due to climate change and the growing global population. Alkaline stress could adversely impact plant growth and crop production. This stressor diminishes water quality essential for crop cultivation, consequently impairing plant growth and overall productivity. Gamma-aminobutyric acid (GABA), a non-protein amino acid, may exhibit multifaceted roles in plant responses to adverse environmental conditions. Optimization of crop production in controlled environmental agriculture under artificial light attracted much attention. In the present study, we investigated the effects of different light spectra and GABA concentrations on Lollo Rosso lettuce plants under alkaline stress. Seedlings were placed under different light spectra [red (R), blue (B), white (W), 3R:1B, and 2R:1B:1far red (FR)] and treated with GABA (0 and 50 µmol). Alkaline conditions were instituted by applying NaHCO3 at a concentration of 40 mM. The experiment incorporated a control treatment without NaHCO3. In general, R light exposure caused the highest growth performance of lettuce plants. GABA augmented biomass production in control and alkaline-treated plants across all light spectra. Additionally, it increased the concentrations of photosynthetic and protective pigments under alkaline conditions. GABA also improved the photosynthetic performance under all light spectra. Non-photochemical quenching and pigmentation were enhanced by exposure to B light, especially in plants treated with GABA. Alkaline stress induced an increase in soluble carbohydrate content in the lettuce leaves. These findings highlight the support of GABA application in facilitating coping plants to alkaline stress.

Abstract γ-Aminobutyric acid (GABA) is a non-protein amino acid with multifunctional roles in dynamic plant responses. To determine the effects of exogenous GABA application (0, 25 and 50 µM) on drought response, two chickpea cultivars with contrasting tolerance to water deficit were examined. Plants were exposed to four irrigation levels (irrigation to 100, 60, 40 and 20% field capacity). Water deficit decreased growth, chlorophyll content, and photosynthetic efficiency. It increased electrolyte leakage and lipid peroxidation owing to both higher ROS accumulation and lower antioxidant enzyme activity. These negative effects of water deficit and the alleviating role of GABA application were more prominent in the sensitive, as compared to the tolerant cultivar. Water deficit also increased proline and GABA contents more in the tolerant cultivar, whereas their content was more enhanced by GABA application in the sensitive one. This may confer an additional level of regulation that results in better alleviation of drought damage in tolerant chickpea cultivars. In conclusion, the stimulatory effect of GABA on growth and physiological modulation depends on both the water stress severity and the cultivar sensitivity to it, implying a probable unknown GABA-related mechanism established by tolerant chickpea cultivars; a lost or not gained mechanism in susceptible ones.

Basil (Ocimum basilicum L.) is one of the most important medicinal and aromatic plants. Light intensity is an indispensable factor for plants due to its effect on photosynthesis and physiological processes. Here, we investigated the impact of light intensities and harvesting times on the photosynthesis of green and purple basil. The experiment involved subjecting plants to three different levels of sunlight for 12 days: complete—100%, 50%, and 30%—sunlight. In addition, we evaluated the impact of harvest time during the day. The highest levels of photosynthetic and protective pigments were detected under full sunlight conditions in purple basil harvested at noon. The highest levels of soluble and storage carbohydrates were recorded in the purple basil grown under full sunlight and harvested during the early morning. By contrast, the lowest levels were obtained in plants grown under 30% sunlight and harvested at noon time. Under all light treatments, the maximum quantum yield of photosystem II (FV/FM) was detected at 4 a.m. in both basil varieties; it decreased at noon and increased again at 5 p.m. Non-Photochemical Quenching (NPQ) was most elevated in the green variety under all light intensities at noon. However, the highest NPQ was detected in the purple variety at 8 a.m. The NPQ was lowest in both basil varieties during the early morning and afternoon. Full sunlight at noon caused temporary photoinhibition and reduced carbohydrates while enhancing pigment concentration and photo-protective mechanisms in basil plants.

This study offers new perspectives on the biochemical and physiological changes that occur in wheat following a gene-for-gene interaction with the fungal pathogen Zymoseptoria tritici. The Z. tritici isolate IPO323, carries AvrStb6, while ΔAvrStb6#33, lacks AvrStb6. The wheat cultivar (cv.) Shafir, bears the corresponding resistance gene Stb6. Inoculation of cv. Shafir with these isolates results in two contrasted phenotypes, offering a unique opportunity to study the immune response caused by the recognition of AvrStb6 by Stb6. We employed a variety of methodologies to dissect the physiological and biochemical events altered in cv. Shafir, as a result of the AvrStb6-Stb6 interaction. Comparative analysis of stomatal conductance demonstrated that AvrStb6-Stb6 mediates transient stomatal closures to restrict the penetration of Zymoseptoria tritici. Tracking photosynthetic functionality through chlorophyll fluorescence imaging analysis demonstrated that AvrStb6-Stb6 retains the functionality of photosynthesis apparatus by promoting Non-Photochemical Quenching (NPQ). Furthermore, the PlantCV image analysis tool was used to compare the H2O2 accumulation and incidence of cell death (2, 4, 8, 12, 16, and 21 dpi), over Z. tritici infection. Finally, our research shows that the AvrStb6-Stb6 interaction coordinates the expression and activity of antioxidant enzymes, both enzymatic and non-enzymatic, to counteract oxidative stress. In conclusion, the Stb6-AvrStb6 interaction in the Z. tritici-wheat pathosystem triggers transient stomatal closure and maintains photosynthesis while regulating oxidative stress.

There are diverse types of gelling agents that are used in media cultures. Agar and Gelrite are among the gelling agents used in DKW culture medium, as the common culture medium for the micropropagation of walnut plants. The effects of these gelling agents have not been investigated on the successful production of in vitro explants and the response of the explants to ex vitro evaporative demand is overlooked so far. Stomata and water relations of tissue culture medium determine the successful production of in vitro plants, therefore this experiment was conducted to investigate the effect of two types of gelling agents (Agar and Gelrite) on the stomatal characteristics, transpiration rate (E), and desiccation responses of in vitro walnut explants. Stomatal morphology, transpiration rate, RWC, and some morpho-physiological traits such as shoot length, chlorophyll content, osmotic potential (ψs), proline, and glycine betaine content were evaluated in micropropagated walnut explants cultured on Agar or Gelrite. Analysis of results indicated no considerable changes in the morpho-physiological characteristics of explants grown in DKW medium containing Agar or Gelrite gelling agents. Compared with the medium containing Agar, adding Gelrite to the DKW medium caused a decrease in E and an increase in relative leaf water content (RWC) of the walnut explant's leaves during desiccation. Gelrite induced generation of more closed stomata leading to a reduction in E and increase in RWC during desiccation. This resulted in improvement of walnut plantlet's capacity to conserve their water content and as the consequence promoted ability to prevent ex vitro wilting.

Cadmium (Cd) is a heavy metal that is widely contaminating the environment due to its uses in industries as corrosive reagents, paints, batteries, etc. Cd can easily be absorbed through plant roots and may have serious negative impacts on plant growth. To investigate the mechanisms utilized by plants to cope with Cd toxicity, an experiment was conducted on maize seedlings. We observed that the plant growth and photosynthetic mechanism were negatively influenced during 20 days of Cd stress. The expression levels of ornithine decarboxylase (ORDC) increased in the six seedlings under Cd exposure compared to the control. However, Cd toxicity led to an increase in putrescine (Put) content only on day 15 when compared to the control plants. In fact, with the exception of day 15, the increases in the ORDC transcript levels did not show a direct correlation with the observed increases in Put content. Spermidine and Spermine levels were reduced on day 6 by Cd application, which was parallel with suppressed Spermidine synthase gene. However, an increase in Spermidine and Spermine levels was observed on day 12 along with a significant elevation in Spermidine synthase expression. On day 6, Cd was observed to start accumulating in the root with an increase in the expression of microRNA 528; while on day 15, Cd started to be observed in the shoot part with an increase in microRNA 390 and microRNA 168. These results imply that different miRNAs may regulate polyamines (PAs) in maize under Cd toxicity, suggesting a plant-derived strategy to commit a PAs/miRNA-regulated mechanism/s in different developmental stages (time points) in response to Cd exposure.

Healing and acclimatization are critical in vegetable grafting under controlled environments. Here, we investigated the impacts of LED light qualities on the morphological traits and photosynthetic performance of grafted tomato seedlings. Seeds of the tomatoes “DRW 7806 F1” and “Maxifort” (Solanum lycopersicum × Solanum habrochaites) used as scion and rootstock were planted in 104-cell plug trays into a mixture of cocopeat and perlite (volume ratio: 3 to 1). Survival ratio, above- and underground growth, photosynthetic performance, soluble carbohydrate content, pigmentation, and antioxidant enzymes activity were evaluated following 20 days of exposure to different light qualities, including white (35% B, 49% intermediate spectra, 16% R) light as control, blue, red, and a combination of red (68%) and blue with the same light intensity of 75 ± 5 µmol m−2 s−1. The lowest scion diameter, leaf area, root and shoot dry weight, SPAD value, and the highest scion length and amount of soluble carbohydrate were detected in R-exposed seedlings. Moreover, R-exposed seedlings showed leaf epinasty and reduced photosynthetic performance. On the other hand, RB-exposed seedlings showed the highest leaf area, shoot and root dry weight, plant fresh and dry weight, scion stem diameter and photosystem II efficiency. In addition, superoxide dismutase activity was increased in R-exposed seedlings, while guaiacol peroxidase activity was enhanced in seedlings grown in RB. In conclusion, a combination of R and B is suggested as the suitable light spectrum to promote plant growth and photosynthetic performance in grafted tomato seedlings.

Saffron is the world’s most coveted spicy plant that has medicinal value. Currently, due to diverse types of difficulties in growing this plant outdoor, the tendency to produce it indoor has been increased. Optimized indoor conditions for growing saffron plants is not fully determined so far. This study was conducted to investigate the interactive effects of two plant growth regulators (PGRs), including gibberellic acid (GA3) and γ-aminobutyric acid (GABA) and four light recipes, including white, monochromatic blue, monochromatic red, and a combination of 50% red and 50% blue on the flower yield and phytochemical components (such as crocin, picrocrocin and safranal) in stigmas of indoor-grown saffron. The results showed that exogenous GABA application and combined red and blue LED lights enhanced the performance of saffron flowers in terms of the number of flowers (up to 1.97 per corm) as well as the fresh and dry weight of flowers and stigmas. In saffron, the concentration of three major secondary metabolites is of great importance since it determines its commercial, pharmaceutical quality. GABA induced saffron’s chemical ingredients toward the phytochemicals safranal (up to 5.03%) and picrocrocin (up to 15.8%), while GA3 induced them toward the carotenoid pigment crocin (up to 25.1%). In conclusion, the application of GABA with a combination of red and blue lights enhanced the production of high-quality stigmas and positively affected the yield of flowers in saffron plants.

Chrysanthemum (Chrysanthemum morifolium) is among the most popular ornamental plants, propagated mainly through stem cuttings. There is a lack of information regarding the impact of the lighting environment on the successful production of cuttings and underlying mechanisms. The light spectrum affects plant morphology, growth, and photosynthesis. In the present study, chrysanthemum, cv. ‘Katinka’ cuttings, were exposed to five lighting spectra, including monochromatic red (R), blue (B) lights, and multichromatic lights, including a combination of R and B (R:B), a combination of R, B, and far red (R:B:FR) and white (W), for 30 days. B light enhanced areal growth, as indicated by a higher shoot mass ratio, while R light directed the biomass towards the underground parts of the cuttings. Monochromatic R and B lights promoted the emergence of new leaves. In contrast, individual leaf area was largest under multichromatic lights. Exposing the cuttings to R light led to the accumulation of carbohydrates in the leaves. Cuttings exposed to multichromatic lights showed higher chlorophyll content than monochromatic R- and B-exposed cuttings. Conversely, carotenoid and anthocyanin contents were the highest in monochromatic R- and B-exposed plants. B-exposed cuttings showed higher photosynthetic performance, exhibited by the highest performance index on the basis of light absorption, and maximal quantum yield of PSII efficiency. Although R light increased biomass toward roots, B light improved above-ground growth, photosynthetic functionality, and the visual performance of Chrysanthemum cuttings.

Flavonoids are characterized as the low molecular weight polyphenolic compounds universally distributed in planta. They are a chemically varied group of secondary metabolites with a broad range of biological activity. The increasing amount of evidence has demonstrated the various physiological functions of flavonoids in stress response. In this paper, we provide a brief introduction to flavonoids’ biochemistry and biosynthesis. Then, we review the recent findings on the alternation of flavonoid content under different stress conditions to come up with an overall picture of the mechanism of involvement of flavonoids in plants’ response to various abiotic stresses. The participation of flavonoids in antioxidant systems, flavonoid-mediated response to different abiotic stresses, the involvement of flavonoids in stress signaling networks, and the physiological response of plants under stress conditions are discussed in this review. Moreover, molecular and genetic approaches to tailoring flavonoid biosynthesis and regulation under abiotic stress are addressed in this review.

Reduction of plant growth, yield and quality due to diverse environmental constrains along with climate change significantly limit the sustainable production of horticultural crops. In this review, we highlight the prospective impacts that are positive challenges for the application of beneficial microbial endophytes, nanomaterials (NMs), exogenous phytohormones strigolactones (SLs) and new breeding techniques (CRISPR), as well as controlled environment horticulture (CEH) using artificial light in sustainable production of horticultural crops. The benefits of such applications are often evaluated by measuring their impact on the metabolic, morphological and biochemical parameters of a variety of cultures, which typically results in higher yields with efficient use of resources when applied in greenhouse or field conditions. Endophytic microbes that promote plant growth play a key role in the adapting of plants to habitat, thereby improving their yield and prolonging their protection from biotic and abiotic stresses. Focusing on quality control, we considered the effects of the applications of microbial endophytes, a novel class of phytohormones SLs, as well as NMs and CEH using artificial light on horticultural commodities. In addition, the genomic editing of plants using CRISPR, including its role in modulating gene expression/transcription factors in improving crop production and tolerance, was also reviewed.

The effect of the lighting environment during postharvest storage of ornamentals has largely been neglected in previous research. Anthurium is a cold-sensitive species originating from tropical climates and is widely cultivated all around the world for its colorful spathes. To investigate the effects of light spectrum on the performance of Anthurium cut flowers under cold storage, two cultivars [Calore (red spathe) and Angel (withe spathe)] were placed at low temperature (4°C), either in darkness (D) or under different light spectra [red (R), blue (B), 70:30% red:blue (RB), and white (W)] at an intensity of 125 µmol.m−2.s−1. In both cultivars, the longest and shortest vase lives were observed in spathes exposed to the R and B spectra, respectively. In both cultivars, electrolyte leakage (EL) of spathe was highest under the B and W spectra and lowest under the R spectrum. The highest rate of flower water loss from the spathes was observed under the B-containing light spectra, whereas the lowest rate of water loss was observed in D and under the R spectrum. Negative correlations were observed between EL and vase life and between anthocyanin concentration and EL for both Anthurium cultivars. A positive correlation was found between anthocyanin concentration and vase life. For both Anthurium cultivars, spectral light composition with higher percentage of B resulted in higher EL and as a result shorter vase life in cut flowers under cold storage condition. The negative effect of the B light spectrum on vase life of Anthurium can be explained through its effect on water loss and on oxidative stress and membrane integrity. The quality of Anthurium cut flowers should benefit from environments with restricted B light spectrum during postharvest handling.

Improving marketability and extension of vase life of cut flowers has practical significance for the development of the cut flower industry. Although considerable efforts have been made over many years to improve the vase life of cut flowers through controlling the immediate environment and through post-harvest use of floral preservatives, the impact of lighting environment on vase life has been largely overlooked. In the current study, the effect of three LED light spectra [white (400–730 nm), blue (peak at 460 nm), and red (peak at 660 nm)] at 150 μmol m–2 s–1 on vase life and on physiological and biochemical characteristics of carnation cut flowers was investigated. Exposure to blue light (BL) considerably delayed senescence and improved vase life over that of flowers exposed to red light (RL) and white light (WL). H2O2 and malondialdehyde (MDA) contents in petals gradually increased during vase life; the increase was lowest in BL-exposed flowers. As a consequence, BL-exposed flowers maintained a higher membrane stability index (MSI) compared to RL- and WL-exposed flowers. A higher activity of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] was detected in petals of BL-exposed flowers, compared to their activities in RL- and WL-exposed flowers. In BL-exposed flowers, the decline in petal carotenoid contents was delayed in comparison to RL- and WL-exposed flowers. Maximum quantum efficiency of photosystem II (Fv/Fm) and a higher percentage of open stomata were observed in leaves of BL-exposed flowers. Sucrose and glucose contents accumulated in petals during vase life; sugar concentrations were higher in BL-exposed flowers than in RL- and WL-exposed flowers. It is concluded that BL exposure improves the vase life of carnation cut flowers through its effect on the antioxidant defense system in petals and on photosynthetic performance in the leaves.

Plants deploy molecular, physiological, and anatomical adaptations to cope with long-term water-deficit exposure, and some of these processes are controlled by circadian clocks. Circadian clocks are endogenous timekeepers that autonomously modulate biological systems over the course of the day–night cycle. Plants’ responses to water deficiency vary with the time of the day. Opening and closing of stomata, which control water loss from plants, have diurnal responses based on the humidity level in the rhizosphere and the air surrounding the leaves. Abscisic acid (ABA), the main phytohormone modulating the stomatal response to water availability, is regulated by circadian clocks. The molecular mechanism of the plant’s circadian clock for regulating stress responses is composed not only of transcriptional but also posttranscriptional regulatory networks. Despite the importance of regulatory impact of circadian clock systems on ABA production and signaling, which is reflected in stomatal responses and as a consequence influences the drought tolerance response of the plants, the interrelationship between circadian clock, ABA homeostasis, and signaling and water-deficit responses has to date not been clearly described. In this review, we hypothesized that the circadian clock through ABA directs plants to modulate their responses and feedback mechanisms to ensure survival and to enhance their fitness under drought conditions. Different regulatory pathways and challenges in circadian-based rhythms and the possible adaptive advantage through them are also discussed.

Low temperatures are a substantial limitation in the geographic distribution of warm-season crops such as cucumber (Cucumis sativus L.). Tolerance to low temperatures varies among different plant species and genotypes when changes in environmental cues occur. Therefore, biochemical and biophysical events should be coordinated to form a physiological response and cope with low temperatures. We examined how light intensity influences the effects of low temperature on photosynthesis and some biochemical traits. We used chlorophyll fluorescence imaging and polyphasic fluorescence transient to analyze cold stress damage by 4 °C. Photosynthetic Photon Flux Densities (PPFDs) of 0, 300, and 600 μmol m−2 s−1, in four accessions of cucumber, were investigated. The results show that the negative effects of cold stress are PPFD-dependent. The adverse effect of cold stress on the electron transport chain is more pronounced in plants exposed to 600 μmol m−2 s−1 than the control and dark-exposed plants, indicated by a disturbance in the electron transport chain and higher energy dissipation. Moreover, biochemical traits, including the H2O2 content, ascorbate peroxidase activity, electrolyte leakage, and water-soluble carbohydrate, increased under low temperature by increasing the PPFD. In contrast, chlorophyll and carotenoid contents decreased under low temperature through PPFD elevation. Low temperature induced a H2O2 accumulation via suppressing ascorbate peroxidase activity in a PPFD-dependent manner. In conclusion, high PPFDs exacerbate the adverse effects of low temperature on the cucumber seedlings.

Photosynthesis of plantlets in tissue culture containers is not considered important, compared to photosynthesis of ex vitro plants, due to the exogenous source of carbohydrates present in tissue culture media. However, CO2 starvation can generate a burst of reactive oxygen species (ROS). We examined this phenomenon in tissue culture, since CO2 levels may become very low during the light period. The research was carried out with lily scales, regenerating adventitious bulblets, and with Arabidopsis seedlings. CO2 starvation was achieved by placing a small vial of concentrated KOH solution in the culture container. CO2 removal reduced the growth of regenerated lily bulblets by 33% or 23%, with or without sucrose in the medium, respectively. In Arabidopsis seedlings, CO2 removal decreased growth by 50% or 78% in the presence or absence of sucrose in the medium, respectively. Therefore, the addition of sucrose as a replacement for photosynthesis resulted in only partial recovery of growth. Staining with nitroblue tetrazolium (NBT) showed little to no ROS in ex vitro growing seedlings, while abundant ROS were detected in seedlings grown under in vitro CO2 starvation. Seedlings grown under normal tissue culture conditions (no CO2 withdrawal) showed low levels of ROS. In lily tissue culture, CO2 starvation decreased the maximum quantum efficiency of photosystem II (Fv/Fm) from 0.69 to 0.60, and in Arabidopsis from 0.76 to 0.62. Fv/Fm of ex vitro lily and Arabidopsis seedlings was 0.77 and 0.79, respectively. This is indicative of a disturbance in photosynthesis functionality and the occurrence of in vitro stress under reduced CO2 concentrations. We conclude that poor growth, in the absence of CO2, was partly due to strongly reduced photosynthesis, while the detrimental effects were most likely due to a burst of ROS.

In agriculture, abiotic stress is one of the critical issues impacting the crop productivity and yield. Such stress factors lead to the generation of reactive oxygen species, membrane damage, and other plant metabolic activities. To neutralize the harmful effects of abiotic stress, several strategies have been employed that include the utilization of nanomaterials. Nanomaterials are now gaining attention worldwide to protect plant growth against abiotic stresses such as drought, salinity, heavy metals, extreme temperatures, flooding, etc. However, their behavior is significantly impacted by the dose in which they are being used in agriculture. Furthermore, the action of nanomaterials in plants under various stresses still require understanding. Hence, with this background, the present review envisages to highlight beneficial role of nanomaterials in plants, their mode of action, and their mechanism in overcoming various abiotic stresses. It also emphasizes upon antioxidant activities of different nanomaterials and their dose-dependent variability in plants’ growth under stress. Nevertheless, limitations of using nanomaterials in agriculture are also presented in this review.

In protected cultivation, increasing the light level via supplementary lighting (SL) is critical to improve external quality, especially in periods with low light availability. Despite wide applications, the effect of light quality remains understated. In this study, the effect of SL quality and nutrient solution electrical conductivity (EC) on growth and flowering of three bromeliad species was investigated. Treatments included solar light, and this supplemented with R90B10 [90% red (R) and 10% blue (B)], R80B20 (80% R and 20% B), and R70B30 (70% R and 30% B). These were combined with an EC of 1 and 2 dS m-l. Irrespective of the light treatment, the higher EC promoted growth, inflorescence emergence, and development in Aechmea fasciata (Lindl.) Baker, whereas adverse effects were noted in Guzmania and Vriesea. The higher EC-induced negative effect in Guzmania and Vriesea was slightly alleviated by SL. With few notable exceptions, SL exerted limited effects on photosynthetic functionality. Depending on the species, SL improved external quality traits. In all species, SL increased root and inflorescence weight and stimulated biomass allocation to generative organs. It also accelerated inflorescence emergence and promoted inflorescence development. In this way, the time to commercial development stage was considerably shortened. These effects were more prominent at R80B20 and R70B30. Under those conditions, for instance, inflorescence emergence occurred 3–5 weeks earlier than in the control, depending on the species. In conclusion, SL with increased B proportion leads to shorter production period owing to faster emergence and improved development of the inflorescence and is recommended for commercial use.

Saffron is a valuable plant and one of the most expensive spices worldwide. Nowadays, there is a tendency to produce this crop in indoor plant production systems. However, the production of saffron is restricted by the need for the reproduction of high-quality corms. In this study, we investigated the effect of different ratios of red (R) and blue (B) light spectra (including 100% B (monochromatic B), 75%, 50%, 40%, 25% B, and 0% B (monochromatic R) on the photosynthetic performance and biomass partitioning as well as morphological and biochemical characteristics of saffron. The growth of flower, root, and corm was improved by increasing the proportion of B to R light. B-grown plants were characterized by the highest photosynthetic functionality with efficient electron transport and lower energy dissipation when compared to R-grown plants. B light directed biomass toward the corms and floral organs, while R light directed it toward the leaves. In saffron, the weight of a daughter corm is of great importance since it determines the yield of the next year. As the ratio of B to R light increased, the daughter corms also became heavier, at the cost of reducing their number, though increasing the proportion of B-enhanced antioxidant capacity as well as the activity of ascorbate peroxidase and catalase while superoxide dismutase activity was enhanced in R-grown plants. In conclusion, B light increased the production of high-quality daughter corms and altered biomass partitioning towards harvestable organs (corms and flowers) in saffron plants.

GABA (gamma-aminobutyric acid) and melatonin are endogenous compounds that enhance plant responses to abiotic stresses. The response of Vicia faba to different stressors (salinity (NaCl), poly ethylene glycol (PEG), and sulfur dioxide (SO2)) was studied after priming with sole application of GABA and melatonin or their co-application (GABA + melatonin). Both melatonin and GABA and their co-application increased leaf area, number of flowers, shoot dry and fresh weight, and total biomass. Plants treated with GABA, melatonin, and GABA + melatonin developed larger stomata with wider aperture compared to the stomata of control plants. The functionality of the photosynthetic system was improved in primed plants. To investigate the photosynthetic functionality in details, the leaf samples of primed plants were exposed to different stressors, including SO2, PEG, and NaCl. The maximum quantum yield of photosystem II (PS II) was higher in the leaf samples of primed plants, while the non-photochemical quenching (NPQ) of primed plants was decreased when leaf samples were exposed to the stressors. Correlation analysis showed the association of initial PIabs with post-stress FV/FM and NPQ. Stressors attenuated the association of initial PIabs with both FV/FM and NPQ, while priming plants with GABA, melatonin, or GABA + melatonin minimized the effect of stressors by attenuating these correlations. In conclusion, priming plants with both GABA and melatonin improved growth and photosynthetic performance of Vicia faba and mitigated the effects of abiotic stressors on the photosynthetic performance.

Boron (B) is an essential nutrient for plant growth and development, exhibiting extremely narrow margins between deficiency and toxicity. B toxicity is devastating for productivity and apparent for a continuously increasing part of agricultural land, under the influence of on-going climate change. In this study, the effects of increased B supply (by using H3BO3) were addressed by examining critical physiological responses of young and mature leaves, which were devoid of toxicity symptoms, in two melon varieties (Armenian cucumbers, cantaloupes). B was primarily translocated through the transpiration stream, and secondarily via the active cell membrane transport system. The B distribution pattern was independent of leaf age, and remained rather unchanged under increased B supply. Armenian cucumbers, exhibiting higher leaf B levels, underwent an enhanced adverse impact on (root and shoot) growth, photosynthetic pigment content, cellular membrane integrity, and also exhibited attenuated antioxidant defense stimulation. Notably, and unlike other abiotic stressors, no evidence of B toxicity-induced systemic reaction was apparent. B toxicity greatly enhanced the transcription of the genes coding for borate influx and efflux channels, an effect that was mostly evident in mature leaves. In conclusion, shoot physiological responses to B toxicity are highly localized. Moreover, the obstruction of the diffusion and the B translocation to the aerial organs under increased B supply is genotype-dependent, governing plant physiological responses.

Salinity has a negative impact on growth and productivity of crops on agricultural lands. Since proline and salicylic acid are used by plants to cope with stress conditions, to test whether they can help olive plants to alleviate negative impacts of salt stress, an experiment was carried out by spraying proline (15 mM) and salicylic acid (0.25 mM) on the plants that subjected to two salinity levels (0 and 100 mM NaCl). Salinity caused an alteration in biomass partitioning; in such a way that shoot vegetative growth was more restricted by salinity than root vegetative growth. Root volume was increased in proline-sprayed plants while salinity caused a decline in the root volume. Salinity resulted in an increase in specific leaf area. Net photosynthesis, stomatal conductance and transpiration rate were decreased by salinity application in root medium. Peroxidase activity decreased in plants that subjected to salinity stress. However, application of proline resulted in improvement of vegetative growth in both control and salinity conditions. Increase in chlorophyll index was observed following proline application, while salinity caused a decline in chlorophyll index. In conclusion, salinity can cause deleterious effects on photosynthesis and vegetative growth of olive trees. Exogenous application of proline can help plants to cope with negative effects of salt stress on olive plants.

The effect of endophytic Bacillus subtilis (strains 10-4, 26D) and their compositions with salicylic acid (SA) on some resistance and quality traits of stored potatoes infected with Fusarium dry rot were studied. The experiments were carried out on hydroponically grown Solanum tuberosum L. tubers that were infected before storage with Fusarium oxysporum and coated with B. subtilis 10-4, 26D with and without exogenous SA, and then stored for six months. It has been shown that 10-4, 26D, 10-4 + SA, and 26D + SA reduced in different levels (up to 30–50%) the incidence of F. oxysporum-caused dry rot (with the highest effect for 10-4 + SA). SA notably enhanced the positive effect of 10-4, while for 26D, such an effect was not observed. All of the tested treatments increased amylase (AMY) and AMY inhibitors activity in infected tubers, while decreased Fusarium-induced protease activity (except in the case of 10-4 + SA, which promoted a slight increase) was revealed. 10-4, 26D, and their compositions with SA decreased (in different degrees) the pathogen-caused lipid peroxidation, proline, and reducing sugars accumulation in potatoes after long-term storage. It was also discovered 10-4 and 26D, regardless of SA presence, decrease pathogen-induced glycoalkaloids α-Solanine and α-Chaconine accumulation and preserved increased levels of starch and total dry matter in infected stored potatoes. The findings indicate endophytic B. subtilis and its compositions with SA is a promising eco-friendly and bio-safe approach to cope with postharvest decays of potato during long-term storage; however, when developing preparations-compositions it should take into account the strain-dependent manner of B. subtilis action together with SA.

Postharvest diseases significantly reduce the shelf-life of harvested fruits/vegetables worldwide. Bacillus spp. are considered to be an eco-friendly and bio-safe alternative to traditional chemical fungicides/bactericides due to their intrinsic ability to induce native anti-stress pathways in plants. This review compiles information from multiple scientific databases (Scopus, ScienceDirect, GoogleScholar, ResearchGate, etc.) using the keywords “postharvest diseases„, “Bacillus„, “Bacillus subtilis„, “biocontrol„, “storage„, “losses„, and “fruits/vegetables„. To date, numerous examples of successful Bacillus spp. application in controlling various postharvest-emerged pathogens of different fruits/vegetables during handling, transportation, and storage have been described in the literature. The mechanism/s of such action is/are still largely unknown; however, it is suggested that they include: i) competition for space/nutrients with pathogens; ii) production of various bio-active substances with antibiotic activity and cell wall-degrading compounds; and iii) induction of systemic resistance. With that, Bacillus efficiency may depend on various factors including strain characteristics (epiphytes or endophytes), application methods (before or after harvest/storage), type of pathogens/hosts, etc. Endophytic B. subtilis-based products can be more effective because they colonize internal plant tissues and are less dependent on external environmental factors while protecting cells inside. Nevertheless, the mechanism/s of Bacillus action on harvested fruits/vegetables is largely unknown and requires further detailed investigations to fully realize their potential in agricultural/food industries.