The responses of pepper plants to nitrogen form and dissolved oxygen concentration of nutrient solution in hydroponics.

BACKGROUND: The presence of oxygen in the growth medium is absolutely essential for root development and the overall metabolic processes of plants. When plants do not have an adequate oxygen supply for respiration, they can experience a condition known as hypoxia. In order to investigate the impact of different nitrogen forms and varying oxygen levels in nutrient solutions on the growth, photosynthesis, and chlorophyll fluorescence parameters of bell pepper plants, a comprehensive study was conducted. The experiment was designed as a factorial experiment, considering two main factors: nitrogen forms (calcium nitrate and ammonium sulfate) with a fixed nitrogen concentration of 5 mM, and the oxygen levels of the nutrient solutions (ranging from 1.8 ± 0.2 to 5.3 ± 0.2 mg. L-1). RESULTS: The study examined the effects of nitrogen (NH4+ and NO3-) application on various parameters of vegetative growth. The results demonstrated that the use of ammonium (NH4+) led to a reduction in the most measured parameters, including the fresh and dry mass of both the root and shoot, at low O2 concentrations of 1.8 ± 0.2; 2.6 ± 0.2 and 3.8 ± 0.2 mg. L-1. However, an interesting observation was made regarding the impact of oxygen levels on root growth in plants grown with nitrate (NO3-). Specifically, the highest levels of oxygen significantly increased root growth in NO3--fed plants. Additionally, the application of NH4+ resulted in an increase in chlorophyll concentration in the leaves, particularly when combined with high oxygen levels in the nutrient solution. On the other hand, leaves of plants fed with NO3- exhibited higher photosynthetic rate (A), intrinsic water use efficiency (iWUE), and instantaneous carboxylation efficiency (A/Ci) compared to those fed with NH4+. Furthermore, it was found that NO3--fed plants displayed the highest instantaneous carboxylation efficiency at oxygen levels of 3.8 and 5.3 mg. L-1, while the lowest efficiency was observed at oxygen levels of 1.8 and 2.6 mg. L-1. In contrast, NH4+-grown plants exhibited a higher maximal quantum yield of PSII photochemistry (Fv/Fm), as well as increased variable fluorescence (Fv) and maximum fluorescence (Fm), compared to NO3--grown plants. Interestingly, the NO3--fed plants showed an increase in Fv/Fm, Fv, and Fm with the elevation of oxygen concentration in the nutrient solution up to 5.3 mg. L-1. CONCLUSION: This study showed that, the growth and photosynthesis parameters in bell pepper plants are sensitive to oxygen stress in floating hydroponic culture. Therefore, the oxygen level in the nutrient solution must not be lower than 3.8 and 5.3 mg. L-1 in NH4+ and NO3- -supplied culture media or nutrient solutions, respectively.

The growth, nutrient uptake and fruit quality in four strawberry cultivars under different Spectra of LED supplemental light.

An experiment was conducted in a greenhouse to determine the effects of different supplemental light spectra on the growth, nutrient uptake, and fruit quality of four strawberry cultivars. The plants were grown under natural light and treated with blue (460 nm), red (660 nm), and red/blue (3:1) lights. Results showed that the "Parous" and "Camarosa" had higher fresh and dry mass of leaves, roots, and crowns compared to the "Sabrina" and "Albion". The use of artificial LED lights improved the vegetative growth of strawberry plants. All three supplemental light spectra significantly increased the early fruit yield of cultivars except for "Parous". The red/blue supplemental light spectrum also increased the fruit mass and length of the "Albion". Supplemental light increased the total chlorophyll in "Camarosa" and "Albion", as well as the total soluble solids in fruits. The "Albion" had the highest concentration of fruit anthocyanin, while the "Sabrina" had the lowest. The use of supplemental light spectra significantly increased the fruit anthocyanin concentration in all cultivars. Without supplemental light, the "Camarosa" had the lowest concentration of K and Mg, which increased to the highest concentration with the use of supplemental light spectra. All three spectra increased Fe concentration to the highest value in the "Sabrina", while only the red/blue light spectrum was effective on the "Camarosa". In conclusion, the use of supplemental light can increase the yield and fruit quality of strawberries by elevating nutrients, chlorophyll, and anthocyanin concentrations in plants.

Hormetic Effect of Wood Distillate on Hydroponically Grown Lettuce.

The addition of biostimulants to nutrient solutions of hydroponically grown crops to speed up plant growth and improve plant yield and quality has been attracting more and more attention. This study investigated the effects of wood distillate (WD) addition to hydroponically grown lettuce (Lactuca sativa L.) plants. Two concentrations of WD, 0.2% and 0.5%, were added to the nutrient solution, and biometric (i.e., leaf fresh weight, root fresh weight, root length and root surface area), photosynthetic (i.e., chlorophyll a, chlorophyll b, and carotenoid content) and biochemical (i.e., electrolyte leakage, total polyphenols, total flavonoids, and total antioxidant power content) parameters were evaluated. The effects of WD were hormetic, as the 0.2% concentration stimulated biometric and biochemical parameters, while the 0.5% concentration inhibited plant growth. Based on these results, it can be suggested that the addition of 0.2% WD to the nutrient solution has a stimulating effect on the growth of lettuce plants, and could be a successful strategy to boost the yield of crops grown hydroponically.

Ammonium to total nitrogen ratio affects the purslane (Portulaca oleracea L.) growth, nutritional, and antioxidant status.

Purslane (Portulaca oleracea L.) is a widespread weed, which is greatly appreciated for its high nutritional value. The present work evaluated the effect of different ammonium/total nitrogen ratios (NH4/Total N: Nr 0.01-0.15) on growth, physiological and biochemical parameters, and nutrient accumulation in different plant parts of hydroponically grown purslane, under two growing seasons, spring and autumn. Young seedlings of purslane were transferred to a Nutrient Film Technique (NFT) system and they were exposed to different Nr levels. The pH and the electrical conductivity of the nutrient solution were kept constant at 5.8 and 2.3 mS cm-1, respectively. After the end of the cultivation periods (19 days for spring and 22 days for autumn), a series of assessments (growth parameters, mineral content in different plant organs, antioxidant status of the plant, etc.) were done. Plant height, leaf number, root fresh weight and plant biomass revealed decreased trends at the higher NH4/total N ratios, especially during the autumn growing season. Total phenols, flavonoids and antioxidant capacity appeared increased at Nr ≤ 0.10 during both seasons (autumn and spring), revealing higher nitrogen accumulation rates and increased water and nutrient use efficiency. Purslane plants grown in Nr 0.05-0.10 revealed a less intense oxidative stress, with decreased lipid peroxidation levels that was the result of the activation of both enzymatic (superoxide dismutase, catalase and peroxidase) and non-enzymatic (ascorbic acid) antioxidant capacity of the plant. Increased Nr resulted in the accumulation of potassium, while calcium and magnesium levels in leaves were decreased. Additionally, the greater water use efficiency was measured for plants grown under Nr 0.01-0.05. Therefore, the recommended ammonium/total nitrogen ratio for purslane production of increased yield, improved nutritional value and efficient use of water and nitrogen sources is to employ Nr of 0.05, while additional care should be addressed during autumn periods as plants are subjected to greater impacts of the Nr ratio.

Assessment of Growth, Yield, and Nutrient Uptake of Mediterranean Tomato Landraces in Response to Salinity Stress.

Salinity is a major stress factor that compromises vegetable production in semi-arid climates such as the Mediterranean. The accumulation of salts in the soil can be attributed to limited water availability, which can be exacerbated by changes in rainfall patterns and rising temperatures. These factors can alter soil moisture levels and evaporation rates, ultimately leading to an increase in soil salinity, and, concomitantly, the extent to which crop yield is affected by salinity stress is considered cultivar-dependent. In contrast to tomato hybrids, tomato landraces often exhibit greater genetic diversity and resilience to environmental stresses, constituting valuable resources for breeding programs seeking to introduce new tolerance mechanisms. Therefore, in the present study, we investigated the effects of mild salinity stress on the growth, yield, and nutritional status of sixteen Mediterranean tomato landraces of all size types that had been pre-selected as salinity tolerant in previous screening trials. The experiment was carried out in the greenhouse facilities of the Laboratory of Vegetable Production at the Agricultural University of Athens. To induce salinity stress, plants were grown hydroponically and irrigated with a nutrient solution containing NaCl at a concentration that could maintain the NaCl level in the root zone at 30 mM, while the non-salt-treated plants were irrigated with a nutrient solution containing 0.5 mM NaCl. Various plant growth parameters, including dry matter content and fruit yield (measured by the number and weight of fruits per plant), were evaluated to assess the impact of salinity stress. In addition, the nutritional status of the plants was assessed by determining the concentrations of macro- and micronutrients in the leaves, roots, and fruit of the plants. The key results of this study reveal that cherry-type tomato landraces exhibit the highest tolerance to salinity stress, as the landraces 'Cherry-INRAE (1)', 'Cherry-INRAE (3)', and 'Cherry-INRAE (4)' did not experience a decrease in yield when exposed to salinity stress. However, larger landraces such as 'de Ramellet' also exhibit mechanisms conferring tolerance to salinity, as their yield was not compromised by the stress applied. The identified tolerant and resistant varieties could potentially be used in breeding programs to develop new varieties and hybrids that are better adapted to salinity-affected environments. The identification and utilization of tomato varieties that are adapted to salinity stress is an important strategy for promoting agriculture sustainability, particularly in semi-arid regions where salinity stress is a major challenge.

Comparing the Nutritional Needs of Two Solanaceae and One Cucurbitaceae Species Grown Hydroponically under the Same Cropping Conditions.

Switching over to closed-loop soilless culture systems, thus preventing pollution of water resources by nitrates and saving water and fertilizers, requires accurate estimations of the mean nutrient-to-water uptake ratios. To contribute to this objective, three fruit vegetable species (tomato, eggplant, cucumber) were grown hydroponically in a floating system under identical cropping conditions to quantify species differences in nutrient uptake. The composition of the nutrient solution used to feed the crops was identical for all species. The total water consumption and the concentrations of most nutrients (K, Ca, Mg, N, P, Fe, Mn, Zn, Cu, B) in the nutrient solution and the plant tissues were measured at crop establishment and at two different crop developmental stages. The obtained data were used to determine the uptake concentrations (UCs) using two mass balance models, one based on nutrient removal from the nutrient solution and a second based on nutrient recovery in the plant tissues. The experiment was conducted in the spring-summer season. The results revealed that the nutrient uptake concentrations were substantially different between species for all nutrients except for N, while there were also significant interactions between the two methods used for their estimation of some nutrients. Thus, the UCs of N, P, Ca, and some micronutrients were significantly higher when its estimation was based on the removal of nutrients from the nutrient solution compared to recovery from plant tissues, presumably because with the first method, losses due to denitrification or precipitation could not be separated from those of plant uptake. The comparison of the three greenhouse vegetables revealed a similar UC for nitrogen, while cucumber generally showed significantly lower UCs for P and for the micronutrients Fe, Zn, and Cu at both cropping stages compared to the two Solanaceae species. The obtained results can be used to precisely adjust the nutrient supply in closed-loop soilless cultivations to the plant uptake thus avoiding both depletion and accumulation of nutrients in the root environment.

Growing Safer Greens: Exploring Food Safety Practices and Challenges in Indoor, Soilless Production Through Thematic Analysis of Leafy Greens Grower Interviews.

Indoor, soilless production-often referred to more broadly as controlled environment agriculture (CEA)-is increasingly used for the cultivation of leafy greens. Minimal information is currently available regarding food safety practices during production and distribution of leafy greens grown within indoor, soilless environments in the United States (U.S.). This study aimed to describe production challenges and implementation of good agricultural practices among CEA growers. Data collection methods included semi-structured interviews (N = 25) and a supplemental online survey completed by growers (N = 12) in the U.S. Out of 18 total responses (i.e., multiple responses allowed per completed survey), survey data indicated that lettuce (n = 5; 27.8%) was the most commonly grown leafy green, followed by culinary herbs (n = 3; 16.7%) and arugula (n = 3; 16.7%). Most growers (n = 7; 58.3%) grew other agricultural products, specifically other crops in addition to leafy greens. Revenue from sales ranged from US$500 000 per year. Meanwhile, nearly half (n = 5; 45.5%) of respondents (N = 11) were uncertain whether their produce was subject to the FSMA Produce Safety Rule. Most survey respondents used vertical farming techniques (5 out of 11; 45.5%) or some variety of greenhouse (4 out of 11; 36.4%). Based on 35 total responses, leafy greens were most commonly sold to "Commercial Restaurants" (n = 7; 20.0%), "Grocery Stores" (n = 7; 20.0%), "Institutional Foodservice Establishments (hospitals, schools, childcare, long-term care)" (n = 6; 17.1%), and "Wholesaler/Distributers" (n = 6; 17.1%). The 11 interview questions elucidated three major themes: contextual, barriers to risk management and regulatory compliance, and research needs. Thirteen subthemes were identified, and an example of a subtheme within each major theme, respectively, includes worker hygiene and training, regulatory and certification environment, and risk assessments of individual issues.

Iodine biofortification of Swiss chard (Beta vulgaris ssp. vulgaris var. cicla) and its wild ancestor sea beet (Beta vulgaris ssp. maritima) grown hydroponically as baby leaves: effects on leaf production and quality.

BACKGROUND: About 35-45% of the global population is affected by iodine deficiency. Iodine intake can be increased through the consumption of biofortified vegetables. Given the increasing interest in wild edible species of new leafy vegetables due to their high nutritional content, this study aimed to evaluate the suitability of Swiss chard (Beta vulgaris ssp. vulgaris var. cicla) and its wild ancestor sea beet (Beta vulgaris ssp. maritima) to be fortified with iodine. Plants were cultivated hydroponically in a nutrient solution enriched with four different concentrations of iodine (0, 0.5, 1.0, and 1.5 mg L-1 ), and the production and quality of baby leaves were determined. RESULTS: Sea beet accumulated more iodine than Swiss chard. In both subspecies, increasing the iodine concentration in the nutrient solution improved leaf quality as a result of greater antioxidant capacity - the ferric reducing ability of plasma (FRAP) index increased by 17% and 28%, at 0.5 and 1.5 mg L-1 iodine, respectively - the content of flavonoids (+31 and + 26%, at 1 and 1.5 mg L-1 of iodine, respectively), and the lower content of nitrate (-38% at 1.5 mg L-1 of iodine) and oxalate (-36% at 0.5 mg L-1 of iodine). In sea beet, however, iodine levels in the nutrient solution higher than 0.5 mg L-1 reduced crop yield significantly. CONCLUSIONS: Both subspecies were found to be suitable for producing iodine-enriched baby leaves. The optimal iodine levels in the nutrient solution were 1.0 in Swiss chard and 0.5 mg L-1 in sea beet, as crop yield was not affected at these concentrations and leaves contained enough iodine to satisfy an adequate daily intake with a serving of 100 g. © 2023 Society of Chemical Industry.

Development of Smart Irrigation Equipment for Soilless Crops Based on the Current Most Representative Water-Demand Sensors.

Due to the edaphoclimatic conditions in southeast Spain, which are expected to worsen due to climate change, more efficient ways of using water must be found to maintain sustainable agriculture. Due to the current high price of irrigation control systems in southern Europe, 60-80% of soilless crops are still irrigated, based on the experience of the grower or advisor. The hypothesis of this work is that the development of a low-cost, high-performance control system will allow small farmers to improve the efficiency of water use by obtaining better control of soilless crops. The objective of the present study was to design and develop a cost-effective control system for the optimization of soilless crop irrigation after evaluating the three most commonly used irrigation control systems to determine the most efficient. Based on the agronomic results comparing these methods, a prototype of a commercial smart gravimetric tray was developed. The device records the irrigation and drainage volumes and drainage pH and EC. It also offers the possibility of determining the temperature, EC, and humidity of the substrate. This new design is scalable thanks to the use of an implemented data acquisition system called SDB and the development of software in the Codesys programming environment based on function blocks and variable structures. The reduced wiring achieved by the Modbus-RTU communication protocols means the system is cost-effective even with multiple control zones. It is also compatible with any type of fertigation controller through external activation. Its design and features solve the problems in similar systems available on the market at an affordable cost. The idea is to allow farmers to increase their productivity without having to make a large outlay. The impact of this work will make it possible for small-scale farmers to have access to affordable, state-of-the-art technology for soilless irrigation management leading to a considerable improvement in productivity.

Effects of foliar fertilizer application on the growth and fruit quality of commercial melon varieties grown in a soilless culture system.

Several factors influence the quality of melon fruits and foliar fertilizer application is one method for improving their quality. The objectives of this study were: (1) to investigate the response of commercial melon varieties to a soilless culture system in Nakhon Si Thammarat Province, Thailand, and (2) to evaluate the quality of melon fruit under various foliar fertilizer treatments. The experiment was arranged as a completely randomized block design with four replications. Eight commercial melon varieties, including four orange pulp melons (Sandee, Baramee, Sanwan, and Melon cat 697) and four green pulp melons (Kissme, Snowgreen, Melon Princess, and Kimoji), were used in this study. At 1-5 weeks after planting, the growth of the melons was measured using agronomic traits. Four foliar fertilizers (distilled water, micronutrients, secondary nutrients + micronutrients, and amino acid + micronutrients) were sprayed on the melon leaves at 1-5 weeks after pollination, and the growth of the melons, using fruit traits, was recorded. After harvesting, the melons were assessed for the quality of the fruit. This study was conducted at the School of Agricultural Technology and Food Industry's greenhouse and the Food Chemistry Laboratory of the Center for Scientific and Technological Equipment, Walailak University. In nearly all of the observed growth weeks, the data demonstrate that most agronomic and fruit traits were significantly different between the melon varieties. Sandee, Baramee, Melon cat 697, and Melon Princess are recommended for planting under Nakhon Si Thammarat's climate, based on fruit size and quality. Foliar fertilizer application impacted the shape, skin color, and quality of the melon. Melons treated with micronutrients, secondary nutrients and micronutrients, and amino acids and micronutrients exhibited better measures of fruit quality than those treated with non-foliar treatments. There was also an interaction observed between melon variety and foliar fertilizer application. Based on measures of fruit quality, Baramee, Melon cat 697, Kissme, and Melon Princess were more responsive to foliar fertilizer application than other melon varieties tested.

Using Date Palm Waste as an Alternative for Rockwool: Sweet Pepper Performance under Both Soilless Culture Substrates.

The degradation of soil quality due to environmental conditions and improper management practices has caused a shrinkage in land areas suitable for crop cultivation. This necessitates a transition towards soilless culture systems, which offer desirable conditions for crop growth and development and increase resource use efficiency. One of the growth-limiting factors in soilless culture systems is the type of growing substrate. The use of more sustainable resources and environmentally friendly growing substrates is a challenge that affects the soilless culture industry. This work evaluates the efficacy of date palm waste (DPW) and rockwool as growing substrates for sweet pepper (Capsicum annuum L.) under greenhouse conditions. The plant height, stem diameter, average total leaf area, φPSII, and Fm' of leaf fluorescence show significant increases when plants are grown in rockwool. No differences are found in terms of the total yield or the number of marketable fruits and fruit quality between the two substrates. However, the DPW substrate shows a significant decrease in the number of unmarketable fruits and number of Blossom End Rot (BER) fruits. Plants grown in both growing substrates consume equal water amounts for the optimal fruit production, while the water use efficiency of rockwool is better than that of DPW. Our results highlight DPW's role in soilless production and as a key solution for resource-saving production systems.

Reuse of coir, peat, and wood fiber in strawberry production.

Introduction: Production of strawberries in greenhouses and polytunnels is gaining popularity worldwide. This study investigated the effect of reuse of coir and peat, two substrates commonly adapted to soilless strawberry production, as well as stand-alone wood fiber from Norway spruce, a promising substrate candidate. Methods: The experiment was performed in a polytunnel at NIBIO Apelsvoll, Norway, and evaluated both virgin substrates, as well as spent materials that were used in one or two years. Yield, berry quality and plant architecture of the strawberry cultivar 'Malling Centenary' were registered. In addition, chemical and physical properties of virgin and reused substrates were investigated. Results: While plants grown in peat and wood fiber had highest yield in the first year of production, the berry yield was slightly reduced when these substrates were utilized for the second and third time. However, yield was comparable to the yield level attained in new and reused coir. Interestingly, berries grown in wood fiber had a tendency to a higher sugar accumulation. This substrate also produced the highest plants. Stand-alone wood fiber was the substrate with the highest accumulation of nitrogen during the three consecutive production cycles. All three investigated materials revealed a trend for decreased potassium accumulation. Wood fiber is characterized by the highest percentage of cellulose, however after three years of production the cellulose content was reducedto the same levels as for coir and peat. Discussion: Implementation of wood fiber as a growing medium, as well as general practice of substrate reuse can be therefore an achievable strategy for more sustainable berry production.

Differences in primary metabolism related to quality of raspberry (Rubus idaeus L.) fruit under open field and protected soilless culture growing conditions.

Introduction: The raspberry (Rubus idaeus) fruit is characterized by good taste and high acceptability by consumers. Thus, the impact on the quality attributes and metabolites related to raspberry taste should be evaluated in crop alternatives such as the protected soilless culture. This study aimed to evaluate the metabolic changes during fruit development and postharvest of raspberry grown in open field and protected soilless culture and their relationship with quality parameters and sensory perception. Methods: In this study, the quality parameters and polar metabolites -sugar and amino acids- content were evaluated during raspberry ripening. In addition, ripe fruit was stored at 1 °C for five days, followed by one day of shelf life at 20 °C. Results: The physiological and quality parameters showed typical changes during ripening in both growing conditions: a constant production of CO2, a drastic loss of firmness, an increase in weight and soluble solids content, loss of acidity, and a turning to red color from the green to fully ripe fruit stages in both growing conditions. Fruit from the protected soilless culture had significantly higher weight but a lower soluble solids content. The metabolic analysis showed differences in primary metabolites content during ripening and storage at 1 °C between both growing conditions. The raspberries grown in the open field showed higher contents of sugars such as D-glucose and D-fructose. On the contrary, the fruit from the protected soilless culture showed higher contents of some amino acids such as L-alanine, L-serine and L-valine, among others. The sensorial panel showed significant differences in the perception of the sweetness, acidity, color and firmness of ripe fruit from both growing conditions. Discussion: The present study provides interesting and useful results with direct commercial application for this alternative growing system, mainly in areas where soil and water scarcity are a reality.

Agarose hydrogel composite supports microgreen cultivation with enhanced porosity and continuous water supply under terrestrial and microgravitational conditions.

Hydrogels are attractive soilless media for plant cultivation with strong water and nutrient retention. However, pristine hydrogels contain mostly ultra-micro pores and lack air-filled porosity for root zone aeration. Herein we report a porous hydrogel composite comprising an agarose network and porous growing mix particle (GMP) fillers. The agarose backbone allowed the composite to sustain a 12-d growth cycle for red cabbage microgreens without the need for watering or crew interaction. Moreover, the GMP induced greater total pore volume and increased the prevalence of pores >30 µm by 8-fold. Further investigation suggested that the nutrients from GMP accounted for a 54 % increase in microgreen yield over pristine hydrogel, while the porous structure introduced by GMP improved the yield by another 44 %. Increased air-filled porosity accelerated the water transport and loss of hydrogel but maintained favorable water potential levels for plant extraction. Finally, the hydrogel composite supported microgreen growth satisfyingly under simulated microgravity despite some morphological changes. Results of this study reveal a novel growth substrate that is lightweight, convenient, and water-efficient, while effectively sustaining plant growth for multiple applications including indoor farming and space farming.

Understanding the Postharvest Phytochemical Composition Fates of Packaged Watercress (Nasturtium officinale R. Br.) Grown in a Floating System and Treated with Bacillus subtilis as PGPR.

The physiological changes and phytochemical pathways of processed watercress (Nasturtium officinale R. Br.) undergone during storage are not well known. The objective of this work was to evaluate the respiration rate and the inherent and external quality of watercress inoculated with B. subtilis and packaged as a fresh-cut product and stored at 4 °C for 11 days. Watercress was grown using continuous flotation (FL) in a greenhouse using substrate disinfection and inoculated or not with Bacillus subtilis as a plant-growth-promoting rhizobacteria (PGPR). The fresh-cut watercress respiration rate and phytochemical profile changed during the shelf life. The inherent phytochemical compounds were retained during the storage of the fresh-cut salad bags. The best results were found in watercress grown in a disinfected substrate but were less satisfactory when seeds and substrates were inoculated with PGPR. In general, the external quality and the pigment contents progressively decreased during the shelf life and the browning enzyme activities responsible for phenolic oxidation increased at different intensities throughout storage. At the end of the shelf-life period, the fresh weight loss of the fresh-cut product was less than 1% of the original weight. The results demonstrated that watercress grown in FL is a standardised baby leaf vegetable that is suitable for processing in the fresh-cut industry and for storing for more than 10 days. Unclear results were obtained for Bacillus subtilis in the postharvest period due to the inconsistent responses of the different analysed parameters.

Evaluation of Vetiver Volatile Compound Production under Aeroponic-Grown Conditions for the Perfume Industry.

Vetiver (Chrysopogon zizanioides (L.) Roberty) is a major tropical perfume crop. Access to its essential oil (EO)-filled roots is nevertheless cumbersome and land-damaging. This study, therefore, evaluated the potential of vetiver cultivation under soilless high-pressure aeroponics (HPA) for volatile organic compound (VOC) production. The VOC accumulation in the roots was investigated by transmission electron microscopy, and the composition of these VOCs was analyzed by gas chromatography coupled with mass spectrometry (GC/MS) after sampling by headspace solid-phase microextraction (HS-SPME). The HPA-grown plants were compared to plants that had been grown in potting soil and under axenic conditions. The HPA-grown plants were stunted, demonstrating less root biomass than the plants that had been grown in potting soil. The roots were slender, thinner, more tapered, and lacked the typical vetiver fragrance. HPA cultivation massively impaired the accumulation of the less-volatile hydrocarbon and oxygenated sesquiterpenes that normally form most of the VOCs. The axenic, tissue-cultured plants followed a similar and more exacerbated trend. Ultrastructural analyses revealed that the HPA conditions altered root ontogeny, whereby the roots contained fewer EO-accumulating cells and hosted fewer and more immature intracellular EO droplets. These preliminary results allowed to conclude that HPA-cultivated vetiver suffers from altered development and root ontology disorders that prevent EO accumulation.

Biochar and cow manure organic fertilizer amendments improve the quality of composted green waste as a growth medium for the ornamental plant Centaurea Cyanus L.

This study is aimed to examine the combined effects of biochar (BC) and cow manure organic fertilizer (CM) added to composted green waste (CGW) on the growth of Centaurea cyanus L. (cornflower) plants. With a constant amount of CGW, the research adjusted the addition ratios of BC as 0%, 15%, 2and 5%, and CM as 0%, 10%, 20%, respectively (the base of % is the volume of CGW). According to the above proportion, the growth media were prepared to culture cornflower seedlings. After a cultivation period of 180 days, growth indexes, ornamental indexes, and nutrient content of cornflower plants were measured to identify the optimal combination of BC and CM. The results showed that the additives BC and CM could significantly improve the plant growth and the nutrient content of cornflower plants, especially when added the two simultaneously. Compared with CGW without amendments, CGW amended with 15% BC and 10% CM increased shoots fresh weight, roots fresh weight, total nitrogen content, flower number, and total chlorophyll content of cornflower plants by 159.1%, 25.0%, 68.9%, 218.8%, and 26.4%, respectively. In conclusion, BC and CM addition could improve the quality and increase the agronomic value of CGW, and the CGW amended with 15% BC and 10% CM was an ideal growth media for cornflower plant.

El uso del lisímetro de pesada en clavel (Dianthus caryophyllus L.) genera ahorro en fertirriego / The use of the weighing lysimeter in carnation (Dianthus caryophyllus L.) generates saving in fertigation

RESUMEN El exceso o déficit en el volumen de fertirriego genera desbalances nutricionales, en razón a que influyen en el pH y la CE, afectando el desempeño de las plantas. Además, el descontrol del volumen de fertirriego puede causar excesos de lixiviados con efectos perjudiciales en el medioambiente. La fertirrigación en la producción de clavel en la Sabana de Bogotá, se hace de forma empiríca, por tanto, es indispensable ajustar el volumen de fertirriego a las necesidades del cultivo, para evitar los problemas mencionados. Por esta razón, se evaluó el efecto del control del volumen de fertirriego con lisímetro de peasada, en comparación con el manejo del fertirriego tradicional, en el desempeño de las plantas de miniclavel, sembradas en sutrato, en condiciones de invernadero. Para la evaluación, se realizó un diseño experimental en bloques completos al azar, con los tratamientos de sistema de cultivo con lisímetro (CL) y sistema de cultivo con fertirriego tradicional sin lisímetro (SL). Las variables evaluadas fueron volumen de riego, contenido nutricional de planta completa en cinco estadios fenológicos, pH y nutrientes mayores y secundarios (Ca-Mg), en el sustrato y en la solución drenada. El CL genera un ahorro en el volumen de fertirriego en comparación con el SL. Se encontraron diferencias en el continuo planta - sustrato - lixiviado, en N, K, Mg, así como en el pH del sustrato. El CL fue más eficiente, al generar mayor acumulación de masa seca, con el uso de menos agua y nutrientes, sin afectar el rendimiento, ni la calidad.

ABSTRACT The amount of fertigation excess or deficit generates nutritional unbalances given it affects pH, CE, and the nutrients balance influencing the plant development performance. In addition, the uncontrolled fertigation volume can cause an excess of leachates with detrimental effects on the environment. The Fertigation in carnation production in the Bogotá savanna is done empirically, therefore, it is essential to adjust the fertigation volume to the needs of the crop to avoid the mentioned problems. For this reason, the effect of the control of the fertigation volume with weighting lysimeters was evaluated in comparison with the management of traditional fertigation in the performance of the spray carnation plants sown in substrate under greenhouse conditions. For the evaluation, an experimental design was carried out in complete randomized blocks with a lysimeter crop system (LCS) and a traditional crop system without a lysimeter (WLS) as treatments. Irrigation volume, whole plant nutritional content in five phenological stages, pH, primary and secondary (Ca - Mg) nutrients in the substrate, and drainage solution were the variables evaluated. The LCS generates saving in the use of fertigation compared with WLS. Differences were found in the continuum plant - substrate - leached in N, K, Mg, as well as in the pH of the substrate. The LCS treatment was more efficient by generating greater dry mass accumulation, with the use of less water and nutrients without affecting the yield or quality.

Beneficial Effects of the Five Isolates of Funneliformis mosseae on the Tomato Plants Were Not Related to Their Evolutionary Distances of SSU rDNA or PT1 Sequences in the Nutrition Solution Production.

The symbiosis and beneficial effects of arbuscular mycorrhizal fungi (AM fungi) on plants have been widely reported; however, the effects might be unascertained in tomato industry production with coconut coir due to the nutrition solution supply, or alternatively with isolate-specific. Five isolates of AM fungi were collected from soils of differing geographical origins, identified as Funneliformis mosseae and evidenced closing evolutionary distances with the covering of the small subunit (SSU) rDNA regions and Pi transporter gene (PT1) sequences. The effects of these isolates on the colonization rates, plant growth, yield, and nutrition uptake were analyzed in tomato nutrition solution production with growing seasons of spring-summer and autumn-winter. Our result indicated that with isolate-specific effects, irrespective of geographical or the SSU rDNA and PT1 sequences evolution distance, two isolates (A2 and NYN1) had the most yield benefits for plants of both growing seasons, one (E2) had weaker effects and the remaining two (A2 and T6) had varied seasonal-specific effects. Inoculation with effective isolates induced significant increases of 29.0-38.0% (isolate X5, T6) and 34.6-36.5% (isolate NYN1, T6) in the plant tissues respective nitrogen and phosphorus content; the plant biomass increased by 18.4-25.4% (isolate T6, NYN1), and yields increased by 8.8-12.0% (isolate NYN1, A2) compared with uninoculated plants. The maximum root biomass increased by 28.3% (isolate T6) and 55.1% (isolate E2) in the autumn-winter and spring-summer growing seasons, respectively. This strong effect on root biomass was even more significant in an industry culture with a small volume of substrate per plant. Our results reveal the potential benefits of using selected effective isolates as a renewable resource that can overcome the suppressing effects of sufficient nutrient availability on colonization rates, while increasing the yields of industrially produced tomatoes in nutrition solution with coconut coir.