Soilless system with supplementary LED light to obtain a high-quality out-of-season production of green beans

Green bean (Phaseolus vulgaris L.) is one of the most important sources of vegetable proteins in the world and it is cultivated all year round, but the light availability, during the dark sea-son, limited its growth. Nevertheless, recent studies conducted on greenhouse horticulture demonstrated that, with the application of light emitting diodes (LEDs) as supplementary light (SL) technology, it is possible to overcome this limitation. Consequently, during the experiment conducted, two cultivars of green bean (‘Saporro’ and ‘Maestrale’) were grown with a soilless system in a cold greenhouse during the fall-winter period. To increase the photoperiod and the daily light integral (DLI), early in the morning, four hours of red (R), blue (B) and red+blue (R+B) supplementary light were supplied by LEDs at 180 μmol·m−2·s−1 (PPFD) at plants level. Plants grown under LEDs improved the yield and the gas exchange system compared with the plants grown under natural light; when B light was supplied as a sole source of SL, it increased the dry matter content and the bright-ness (L*) of the pods. Between the cultivars, ‘Maestrale’ produced 20 g·plant−1 of pods more than ‘Saporro’ but the latter’s colour was brighter (L*) and greener (a*), and ‘Saporro’ also showed the highest photosynthetic efficiency (ΦPSII). In conclusion, ‘Maestrale’ and ‘Saporro’ obtained encouraging out-of-season yields under different LED spectra, but among those B light seems to improve overall crop performances and pods quality

Yield and quality characteristics of brassica microgreens as affected by the NH4:NO3 molar ratio and strength of the nutrient solution

Microgreens are gaining more and more interest, but little information is available on the effects of the chemical composition of the nutrient solution on the microgreen yield. In this study, three Brassica genotypes (B. oleracea var. italica, B. oleracea var. botrytis, and Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort) were fertigated with three modified strength Hoagland nutrient solutions (1/2, 1/4, and 1/8 strength) or with three modified half-strength Hoagland nutrient solutions with three different NH4:NO3 molar ratios (5:95, 15:85, and 25:75). Microgreen yields and content of inorganic ions, dietary fiber, proteins, alpha;-tocopherol, and β-carotene were evaluated. Micro cauliflower showed the highest yield, as well as a higher content of mineral elements and alpha;-tocopherol (10.4 mg 100 g-1 fresh weight (FW)) than other genotypes. The use of nutrient solution at half strength gave both a high yield (0.23 g cm-2) and a desirable seedling height. By changing the NH4:NO3 molar ratio in the nutrient solution, no differences were found on yield and growing parameters, although the highest β-carotene content (6.3 mg 100 g-1 FW) was found by using a NH4:NO3 molar ratio of 25:75. The lowest nitrate content (on average 6.8 g 100 g-1 dry weight) was found in micro broccoli and micro broccoli raab by using a nutrient solution with NH4:NO3 molar ratios of 25:75 and 5:95, respectively. Micro cauliflower fertigated with a NH4:NO3 molar ratio of 25:75 showed the highest dry matter (9.8 g 100 g-1 FW) and protein content (4.2 g 100 g-1 FW)

Extraseasonal production in a soilless system and characterisation of landraces of carosello and barattiere (Cucumis melo l.)

Barattiere and Carosello are typical melon (Cucumis melo L.) landraces of Puglia’s (South-ern Italy) biodiversity. Their unripe fruits are locally consumed as an alternative to cucumbers (C. sativus L.) and are appreciated for their qualitative profile. Nevertheless, they are underutilized crops. For the high variability and confusing denominations, a morphological characterization is essential to discriminate and valorise landraces; additionally, it is fundamental to implement the agronomic technique to allow the cultivation outside the natural growth period (summer) by soilless cultivation. Two genotypes of Barattiere (‘Allungato’ and ‘Tondo’), two of Carosello (‘Scopatizzo’ and ‘Tomentoso’ (CAT)) and two of cucumber (‘Baby Star’ and ‘Modan’ hybrids) were vertically grown in the winter–spring period in a rockwool soilless system in a glasshouse with supplemental light. Lan-draces were characterized by morpho-physiological descriptors of melon; fruit biometrics and colour were analysed for all genotypes; productive parameters, leaf fluorescence, and chlorophyll content were measured. Genotypes varied in seeds, stem, leaf, fruit traits and they were andromonoecious; Carosello flowered earlier and produced more than Barattiere; CAT fruits were hairy and elongate, while other genotypes tended to rounder and glabrous fruits. Although landraces grew slower than cucumbers, both produced marketable fruits and the production of Carosello was comparable to cucumbers. In conclusion, Barattiere and Carosello have a productive potential and one vertically trained stem in a soilless system is appropriate for their extra-seasonal production

FYVE-Dependent Endosomal Targeting of an Arrestin-Related Protein in Amoeba

International audienceBACKGROUND: Visual and β-arrestins are scaffolding proteins involved in the regulation of receptor-dependent intracellular signaling and their trafficking. The arrestin superfamilly includes several arrestin domain-containing proteins and the structurally related protein Vps26. In Dictyostelium discoideum, the arrestin-domain containing proteins form a family of six members, namely AdcA to -F. In contrast to canonical arrestins, Dictyostelium Adc proteins show a more complex architecture, as they possess, in addition to the arrestin core, other domains, such as C2, FYVE, LIM, MIT and SAM, which potentially mediate selective interactions with either lipids or proteins. METHODOLOGY AND PRINCIPAL FINDINGS: A detailed analysis of AdcA has been performed. AdcA extends on both sides of the arrestin core, in particular by a FYVE domain which mediates selective interactions with PI(3)P, as disclosed by intrinsic fluorescence measurements and lipid overlay assays. Localization studies showed an enrichment of tagged- and endogenous AdcA on the rim of early macropinosomes and phagosomes. This vesicular distribution relies on a functional FYVE domain. Our data also show that the arrestin core binds the ADP-ribosylation factor ArfA, the unique amoebal Arf member, in its GDP-bound conformation. SIGNIFICANCE: This work describes one of the 6 arrestin domain-containing proteins of Dictyostelium, a novel and atypical member of the arrestin clan. It provides the basis for a better understanding of arrestin-related protein involvement in trafficking processes and for further studies on the expanding roles of arrestins in eukaryotes

Regulators of AWC-Mediated Olfactory Plasticity in Caenorhabditis elegans

While most sensory neurons will adapt to prolonged stimulation by down-regulating their responsiveness to the signal, it is not clear which events initiate long-lasting sensory adaptation. Likewise, we are just beginning to understand how the physiology of the adapted cell is altered. Caenorhabditis elegans is inherently attracted to specific odors that are sensed by the paired AWC olfactory sensory neurons. The attraction diminishes if the animal experiences these odors for a prolonged period of time in the absence of food. The AWC neuron responds acutely to odor-exposure by closing calcium channels. While odortaxis requires a Gα subunit protein, cGMP-gated channels, and guanylyl cyclases, adaptation to prolonged odor exposure requires nuclear entry of the cGMP-dependent protein kinase, EGL-4. We asked which candidate members of the olfactory signal transduction pathway promote nuclear entry of EGL-4 and which molecules might induce long-term adaptation downstream of EGL-4 nuclear entry. We found that initiation of long-term adaptation, as assessed by nuclear entry of EGL-4, is dependent on G-protein mediated signaling but is independent of fluxes in calcium levels. We show that long-term adaptation requires polyunsaturated fatty acids (PUFAs) that may act on the transient receptor potential (TRP) channel type V OSM-9 downstream of EGL-4 nuclear entry. We also present evidence that high diacylglycerol (DAG) levels block long-term adaptation without affecting EGL-4 nuclear entry. Our analysis provides a model for the process of long-term adaptation that occurs within the AWC neuron of C. elegans: G-protein signaling initiates long-lasting olfactory adaptation by promoting the nuclear entry of EGL-4, and once EGL-4 has entered the nucleus, processes such as PUFA activation of the TRP channel OSM-9 may dampen the output of the AWC neuron

Led and hps supplementary light differentially affect gas exchange in tomato leaves

: Using light emitting diodes (LED) instead of conventionally used high pressure sodium (HPS) lamps as a supplemental light source in greenhouses results in a higher efficacy (μmol light per J electricity) and makes it possible to customize the light spectrum. To explore the effects of LED and HPS on gas exchange, thermal relations, photosynthesis, and water status of young tomato plants, seven genotypes were grown in a greenhouse under LED (95% red, 5% blue) or HPS lamps in four experiments differing in the fraction of lamp light over natural light. HPS lights emit a broader spectrum of red (40%), green-yellow (50%), blue (5%), and far-red (5%) and a substantial amount of infrared radiation (heat). Young tomato plants grown under LED showed lower leaf temperature and higher stomatal density, stomatal conductance (gs) and transpiration rate (E) than plants grown under HPS; this may be due to the different supplemental light spectrum. The young plants grown under LED tended to have increased photosynthetic capacity. Furthermore, the water stress indices CWSI and IG, which were obtained using thermal imaging, were positively correlated with gas exchange-derived gs and E, putting forward the use of thermal imaging for the phenotyping of transpiration. Under LED light, photosynthetic gas exchange was generally increased, which agreed with the water stress indices. The extent of this increase was genotype-dependent. All differences between LED and HPS were smaller in the experiments where the fraction of lamp light over natural light was smaller

Blue LED light irradiation enhances yield in green beans

Green beans (Phaseolus vulgaris L.) is one of the most interesting vegetable crops for extra-seasonal cultivation, as it may achieve high prices on the market, making its cultivation more remunerative when done in greenhouse. However, indoor cultivation may be subjected to disadvantageous conditions in terms of light quantity, especially in autumn and winter, and this condition may be limited for green bean indoor cultivation. Light-emitting diode (LED) technology is gaining popularity, as it allows using specific spectra to increase light quantity and modulate the quality of the spectrum, while its cost is decreasing. In this study, we applied three light spectra (blue (450 nm), red (660 nm), and blue plus red light, during four hours before sun rise, with an intensity of 500 μmol m-2 s-1) supported by LED fixtures to enhance yield of green beans in a cold greenhouse. The LED treatments received also sunlight, and the control treatment was the sunlight without LED. Plants ('Maestrale') were transplanted on August 22 and harvested from November 4 to December 18, 2019. Colour (CIELab colour scale) of pods, SPAD of leaves and yield were determined. Based on our results, with the addition of supplemental blue light, the plants produced more, especially compared to sunlight (on average, 54.7 vs. 47.1 pods plant-1 and 99.8 vs. 78.0 g plant-1). With blue light, the leaves showed SPAD values lower than red light but 5.4% higher than in sunlight, while the green colour (a*) of the pods was less intense with blue light (with or without red light) compared to red light and sunlight (-15.7 vs. -16.6)

Localized foliar application of iodine on tomato: An effective approach for targeted agronomic biofortification

Iodine is an essential mineral for the human body and inadequate intake causes iodine deficiency disorders (IDDs) worldwide. Agronomic biofortification is a promising complementary approach to other strategies to avoid IDDs. It consists of the enrichment of fruit and vegetables with nutritional elements through preharvest techniques. Tomato is an important, nutritious, and widely consumed crop. Despite a poor iodine accumulation in the fruit, tomato is an iodine accumulator. Our research focused on iodine enrichment of two table tomato types (cherry and mini-plum) in a commercial mediterranean greenhouse. Potassium iodate (KIO3) was applied four times through foliar spray at three concentrations (0, 1, 5 mM) at two localized sites of application (at plant apex and at the three leaves above the target truss, “target leaves”) until the mature green stage of a target truss (untreated and the same for each treatment). The application of 1 mM KIO3 solution at the target leaves was the most suitable approach for adequate fruit enrichment. The accumulation of 110 μg•100 g−1 of fresh weight (FW) in cherry and 130 μg•100 g−1 FW for mini-plum tomato largely satisfy the iodine recommended dietary allowance for adults, pregnant and lactating women. Plant health, yield and commercial quality of fruit (color, size, dry matter content, total soluble solids, titratable acidity, pH) were not affected, while some carotenoids and total phenolics were slightly incremented, indicating a possible positive influence on the nutritional quality. In conclusion, foliar application of iodine for the preharvest enrichment of tomato was a successful approach to biofortification in a commercial greenhouse. That suggests further research is needed to investigate and improve the iodine biofortification techniques in different crops and systems

Nutritional value of five new tomato (Solanum lycopersicum L.) hybrids in a Mediterranean commercial glasshouse

Tomato fruit (Solanum lycopersicum L.) is one of the pillars of the Mediterranean diet. Every day it is possible to find at the market tomatoes with different shape, colour and weight, that give different nutritional intake to the human diet. Five tomato hybrids (F1) - two “cherries” ('Juanita' and 'Sorentyno'), two red “plums” ('Apeticio' and 'Solarino'), and one yellow plum ('Maggino') - were compared in a commercial glasshouse in southern Italy. Plants were transplanted on August 23, 2019 and grown on rockwool slabs. Determinations on yield and quality of tomatoes were made on the third truss for each cultivar. 'Maggino' produced less than red plum tomatoes (345 vs. 396 g plant-1), and resulted the most contrasting one. Indeed, as far as carotenoids, zeaxanthin and beta cryptoxanthin were detected only in 'Maggino' (0.09 and 0.12 mg kg-1 fresh weight (FW), respectively). Moreover, lycopene was not detected in 'Maggino' and this is the reason why a low level of lipophilic antioxidant activity was also observed. Reversely, in the other four hybrids, lycopene was present at levels ranging from 46.0 to 63.6 mg kg-1 FW and a much higher level of lipophilic antioxidant activity was in turn observed. β-carotene and lutein were found in all cultivars and their content ranged from 0.27 to 3.16 mg kg-1 FW and from 0.29 to 0.47 mg kg-1 FW, respectively. Furthermore, 'Maggino', 'Apeticio', and 'Sorentyno' showed higher levels of α-tocopherol than 'Juanita' and 'Solarino'. 'Maggino' also revealed lower levels of ascorbate compared to the other hybrids, although hydrophilic antioxidant activity did not seem to be affected, likely due to the total phenolic levels which were not reduced in this cultivar. 'Maggino' fruits also showed reduced total soluble solids and dry matter compared to the red fruits