Supplemental LED increases tomato yield in mediterranean semi-closed greenhouse

Supplemental light (SL) is a technique used to increase horticulture yield, especially in northern countries, where the Daily Light Integral (DLI) is a limiting factor during fall and winter, and which could also be used to obtain higher tomato yield at the mediterranean latitude. In this study, three tomato hybrid (F1) cultivars were grown for year-round production in a commercial semi-closed glasshouse in Southern Italy: two of the cherry fruit-type (‘Juanita’ and ‘Sorentyno’) and one mini plum fruit-type (‘Solarino’). From 120 to 243 days after transplant, light-emitting diode (LED) toplights were used as SL, with a photoperiod of 18 h. The main climatic parameters inside and outside the glasshouse were recorded, and tomato plants’ development and yield were examined. Plants grown with LEDs had longer stems as compared to control treatment (9.53 vs. 8.79 m), a higher stem thickness and yielded more trusses. On average, the yield was 21.7% higher with LEDs. ‘Sorentyno’ was the cultivar with the highest cumulated productivity when it was grown under SL. However, the cultivar with best light use efficiency under LEDs was ‘Solarino’. Therefore, supplemental LED from mid-December until march enhanced tomato growth and yield, opening a favorable scenario for large-scale application of this technology also in the mediterranean area

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)

Supplementary light differently influences physico-chemical parameters and antioxidant compounds of tomato fruits hybrids

One of the challenges for agriculture in the coming years will be producing more food avoiding reducing the nutritional values of fruits and vegetables, sources of nutraceutical com-pounds. It has been demonstrated that light-emitting diodes (LEDs) used as a supplementary light (SL) technology improve tomato yield in Mediterranean greenhouses, but few data have been re-ported about SL effects on fruit physio-chemical parameters. In this study, three tomato hybrid (F1) cultivars were grown for year-round production in a commercial semi-closed glasshouse in Southern Italy: red cherry type (“Sorentyno”), red plum type (“Solarino”), and yellow plum type (“Maggino”). From 120 to 243 days after transplant (DAT), Red/White/Blue LEDs were used as SL. The fruits harvested 180 DAT were analyzed and those obtained under LEDs had 3% more dry weight, 15% more total soluble solids, and 16% higher titratable acidity than fruits grown only under natural light. Generally, the antioxidant activity and the mineral profile of the fruits were not negatively influenced by SL. Lycopene content was unchanged and vitamin C content of “Sorentyno” even increased by 15% under LEDs. Overall, LEDs used as SL technology could be one of the tools used by agriculture in Mediterranean basin to produce more food maintaining high quality production

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

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

Supplemental lighting with LED for efficient year-round production of soilless tomato in a Mediterranean greenhouse

Supplemental lighting (SL) is currently arising increasing interest in Mediterranean greenhouse for efficient year-round production. Compared to traditional high-pressure sodium lamps, light-emitting diode (LED) grow lights provide important advantages [a generally touted higher efficiency in terms of micromoles of photosynthetic photon flux (PPF) produced per unit of electricity; a provided light with a spectral distribution used efficiently by plants; the possibility to provide specific spectra able to induce specific responses by plants]. In this research we compared the effects of inter-light LEDs ['R+B': red (660 nm) + blue (450 nm) + red (660 nm) light; 'FR': red blue + blue red + infrared (730 nm) light] toward natural light growing conditions ('C', control) on the performance of soilless greenhouse tomato ('DRW 7723' and 'Diamantino' cultivars, both grafted on 'Maxifort'). The experiment was carried out at the experimental farm “La Noria” (Mola di Bari, South Italy). SL was operated automatically by a system composed by a CR1000 datalogger and a quantum sensor: for 16 h d-1, the system evaluated every 4 s the incoming sunlight in the greenhouse, and turned on the LED light bars whenever the ambient PPFD dropped below 200 μmol m-2 s-1 until the PPFD from sunlight rose above the set-point again. The duration of the supplemental light activation ranged from about 7 to 16 h d-1 (values registered in October 2018 and November-December-January 2019, respectively) depending on the ambient light conditions during the growing cycle. Model equations describing daily light integral (DLI) trends inside the greenhouse and power consumption as affected by light conditions were obtained. Plants grown without SL showed, on average, 19% lower yield and 16% lower fruits number than tomato plants grown with SL. Also, water use efficiency and fruit quality traits were positively affected, but the response can be highly dependent on the cultivar

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