Open Field Cultivation Research Articles

ON THE PRODUCTION OF SEED PROGENY OF METASEQUOIA GLYPTOSTROBOIDES HU ET W. C. CHENG (TAXODIACEAE) IN ST. PETERSBURG

Metasequoia glyptostroboides Hu et W.C. Cheng has been grown in the Peter the Great Botanical Garden of the BIN RAS since 1952, where it was first introduced into cultivation in Russia. It is the most winter-hardy representative of the Taxodiaceae family suitable for open field culture in St. Petersburg. The best specimens reached 14.4 m in height with a trunk diameter of 29 cm at the age of 69 years. In 2018, seed production was recorded for the first time. Seed offspring were obtained in 2020. In the conditions of the warming of the climate of St. Petersburg in the first two decades of the 21st century, there is a surge in the generative ability of woody exotics, an increasing number of trees and shrubs are beginning to bear fruits and seeds.

Performance of Organic Manures on Growth and Yield of Tomato (<i>Lycopersicon esculentum</i> L.) Under Jatropha Based Alley Cropping System

Field experiment was conducted to investigate the effect of different organic manures (FYM + Neem cake + Vermicompost) application on growth and yield of tomato (Lycopersicon esculentum L.) under Jatropha based alley cropping system at the forest nursery, School of Forestry and Environment, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad (U.P.) India. Total of eight treatments including control were replicated three times. The data recording on plant height, number of branches and number of leaves per plant, number of fruit per plant, fruit weight, fruit diameter, fruit yield per plant at different interval 30 days, 60 days, 90 days and 120 days to evaluate the performance of different combination of organic manures on growth and yield of tomato were found to be maximum in T 7 [FYM + Neem cake +Vermicompost] followed by T 5 [FYM + Vermicompost], T 4 [Fym + Neem cake], T 6 [Neem + Vermicompost], T 3 [Vermicompost] and minimum in T 0 (Control) under the jatropha based alley cropping system. Therefore FYM + Neem cake +Vermicompost can be best combination of jatropha trees if tomato is to be planted. Moreover compared to open field cultivation of tomato crops in growth and yield slightly decreased under the jatropha based alley cropping system. This was due to the allelopathic effect of jatropha on tomato. Although growth and yield slightly decreased however tomato cultivation under jatropha based alley cropping system profited by providing biodiesel and tomato crop at the same time period. Ultimately this will help in reaching goals of sustainable agriculture.

Yield, water use efficiency and crop co-efficient of cucumber (Cucumis sativus L.) grown under greenhouse and open field condition

A field experiment was conducted with Chitra variety of cucumber at Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Kumulur in the year 2019-2020. The cucumber seeds were sown under greenhouse and open field condition under drip irrigation system. The micro climatic parameters like maximum and minimum temperature, relative humidity, light intensity were observed. Cucumber plant growth parameters, yield parameters and water use efficiency were recorded. Early flowering and fruit formation (32 days after sowing) was noticed inside greenhouse condition and fruit formation was noticed 40 days after sowing in out-side cultivation. The average length of the fruit was found 20.5 cm inside greenhouse and 17.6 cm for outside cultivation of cucumber. A maximum yield of 11.6 t/ha was recorded inside greenhouse cultivation whereas 7.84 t/ha was recorded for outside cultivation of cucumber. The water use efficiency of 25.7 kg/ha. mm was obtained under green house cultivation whereas water use efficiency of 16.70 kg/ha.mm was recorded in open field cultivation. The crop co-efficient value of 0.67, 0.87, 1.12 and 0.89 were developed for initial, developmental, middle and end stages of crop growth period for open field cultivation. Similarly crop co-efficient value of 0.63, 0.82, 1.05 and 0.88 were developed for initial, developmental, middle and end stages of crop growth period for polyhouse condition of semi arid region.

Estimation of irrigation water requirement of strawberry crop under polyhouse and shadenet house conditions

Strawberry is a commercial crop with high added value, which was extended to new cultivation zones of India.Therefore, it is important to know the suitability of climate condition for growing strawberry in Indian condition. Protected cultivation structures are used to cultivate crops under partial controlled climatic condition to get higher yield and better quality harvest. There are different kinds of protected cultivation structure normally adopted in India such as greenhouse, shadenet house and low tunnels. Exact of amount water and nutrients required to applied to get higher yield through minimizing loss of quality. The objective of the study is to assess the effect of protected cultivation structure on ambient temperature, relative humidity and crop water requirement of strawberry with drip irrigation system grown during winter season (November-February). Reference evapotranspiration was calculated using the FAO-56 Penman-Monteith equation considering the locally recorded weather parameters. Monthly average of daily reference evapotranspiration values are ranging between 1.3 to 3.3 mm day-1, 1.4 to 3.7 mm day-1 and 2.0 to 4.9 mm day-1 for polyhouse, shadenet house and open field, respectively. The total water requirement of drip irrigated straw berry in protected cultivation structure is reduced by about 35.2 % under polyhouse and 25.5 % under shade net house in comparison to open field cultivation.

Response of horticultural crops under variable microclimatic conditions of different protected cultivation structures

Protected cultivation structures provide favorable environment for crop growth thereby achieving greater yield and high quality produce. The objective of this work was to evaluate the microclimate parameters such as temperature, relative humidity, solar radiation and light intensity underdifferent protected cultivation structures in comparison with open field condition. Four types of protected cultivation structures (polyhouse, walking tunnel,shadenet house and modified greenhouse) were considered for the study. Meteorological data of seven years (2010-2016), recorded on daily basis were used for micro climate analysis of different protected cultivation structures. FAO-56 Penman Monteith approach was used to estimate the reference crop evapotranspiration under different kind of protected cultivation structures.Study shows that walking tunnel, polyhouse and modified greenhouse structures offers a solar energy saver and enhances temperature inside the structures. The total water requirement of drip irrigated crops in protected cultivation structure is reduced by about 25% to 35% under different protected cultivation structures in comparison to open field cultivation. This paper also presents the difference incrop yield grown under protected cultivation structures and open field condition.

Estimation of high infection period of root rot pathogen to ginger tubers under an open-field condition

To estimate the infection period of a root rot pathogen of ginger (Pythium myriotylum Drechsler) under an open-field cultivation condition, an inoculation test was conducted under field conditions for two cultivation seasons. The pathogen infection was confirmed by the LAMP method and symptoms were observed from late May 2016 to mid-September and 2017. This demonstrates that the pathogen can infect ginger tubers for more than four months from early to mature stages of the plant under field conditions.

Land-use conversion from open field to greenhouse cultivation differently affected the diversities and assembly processes of soil abundant and rare fungal communities

Soil fungal communities, consisting of a few abundant taxa but many rare taxa, play critical roles in terrestrial ecosystem functioning. However, little is known about ecological processes governing the assembly of abundant and rare sub-communities in response to agricultural intensification, which can threaten soil biodiversity. Here, we performed a regional-scale survey of soil fungal community assembly in different land-use types with an increasing gradient of agricultural intensity, i.e., open field cultivation of main crops (CF) or vegetables (VF), and greenhouse cultivation of vegetables (VG). Results showed that greenhouse cultivation decreased the alpha diversity and spatial turnover rate of soil fungal community. The abundant sub-community was more sensitive to land-use conversion than the rare sub-community. Partitioning the Bray-Curtis dissimilarity found that balanced variation in abundance (i.e., the substitution of individuals by the same number of individuals of a different species), rather than abundance gradients (i.e., one assemblage is a subset of another), accounted for the major shift in fungal beta diversity. Moreover, greenhouse cultivation reduced potential inter-species interactions, and the rare sub-community plays an important role in fungal co-occurrence network. Conversions from CF to VF or VG promoted deterministic processes, which was, to a large extent, associated with changes in soil physicochemical properties. However, conversion from VF to VG decreased deterministic processes. Compared with the rare sub-community, the abundant sub-community with wider niche breadths was more influenced by stochastic processes. Changes in the assembly processes induced by land-use conversion differed between abundant and rare sub-communities. Overall, abundant and rare sub-communities exhibited differential responses to land-use conversion and rare taxa might play a crucial role in maintaining the stability of fungal community.

Effect of rain-shelter cultivation on the monoterpenes profile of Muscat Hamburg grapes and wines

Monoterpenes make important contributions to the aroma of grapes and wine. In this study, the monoterpene profiles and related gene expression patterns were investigated in vitis vinifera cv. Muscat Hamburg grapes grown under open-field and rain-shelter cultivation for two vintages. The results showed bound monoterpenes biosynthesis was repressed during the rainy season. There were no significant differences on the concentration of most of individual monoterpenes in grapes between rain-shelter and open-field cultivation in 2018. Compared with open-field cultivation, grapes under rain-shelter cultivation and the resulting wines had greater contents of monoterpenes in the rainy vintage (2019), in line with the higher expressions of most of the TPSs genes in rain-shelter cultivated grapes. Rain-shelter cultivation might improve tolerance to seasonal rain-induced stresses. The present study has revealed the influence of rain-shelter cultivation on monoterpene compounds in Muscat Hamburg grapes and wines thus providing a useful technique for improving the aroma quality of grapes and wines in the rainy season.

Daucus carota L. Seed Inoculation with a Consortium of Bacteria Improves Plant Growth, Soil Fertility Status and Microbial Community

The present work aimed to study suitability of a consortium of Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria as biofertilizers. Strains were assayed for plant growth-promoting characteristics (i.e., auxins production, phosphate solubilizing capability, and 1-aminocyclopropane-1-carboxylate deaminase activity). The consortium of four bacteria was then inoculated on carrot seeds and tested in an open field experiment. During the open field experiment, plant growth (morphological parameters, chlorophylls, and carotenoids), soil chemical analysis, and molecular and physiological profiles of soils were investigated. Each strain produced different amounts of indole-3acetic acid and several indole-derivates molecules. All strains showed phosphate solubilization capability, while 1-aminocyclopropane-1-carboxylate deaminase activity was only detected in H. seropedicae and B. ambifaria. The bacterial consortium of the four strains gave interesting results in the open field cultivation of carrot. Plant development was positively affected by the presence of the consortium, as was soil fertility and microbial community structure and diversity. The present work allowed for deepening our knowledge on four bacteria, already known for years for having several interesting characteristics, but whose interactions were almost unknown, particularly in view of their use as a consortium in a valid fertilization strategy, in substitution of agrochemicals for a sustainable agriculture.

Enhancement of freshwater production of the seawater greenhouse condenser

Seawater greenhouse (SWGH) is a technology established to overcome issues related to open field cultivation in arid areas, such as the high ambient temperature and the shortage of freshwater. It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body. Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand. The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs, simple design and high efficiency, and to explore the impact of the manipulating six operational variables (inlet air temperature of the humidifier, air mass flowrate of the humidifier, inlet water temperature of the humidifier, water mass flowrate of the humidifier, inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier) on freshwater condensation rate. For this purpose, a direct contact condenser was designed and manufactured. Sixty-four full factorial experiments were conducted to study the effect of the six operational variables. Each variable was operated at two levels (high and low flowrate), and each experiment lasted for 10 min and followed by a 30-min waiting time. Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min. When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production, it was found that the inlet air temperature of the humidifier had the greatest influence, followed by the inlet water temperature of the humidifier; the former had a negative impact while the latter had a positive impact on freshwater production. The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode. The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.

Sensor-Based Nutrient Recirculation for Aeroponic Lettuce Cultivation

The objective of this study was to investigate the effects of used-nutrient solution recirculation on nutrient efficiency improvement and reduction of environmental pollution of an ion-selective electrodes (ISEs)-based recycle-type aeroponic crop cultivation system. A recycle-type aeroponic crop cultivation test bench was fabricated, which consisted of K+, NO3-, and Ca2+ ISEs, pH, and EC sensor, and lettuce were cultivated for inspecting the nutrient solution recirculation process. The specific growth rate of lettuce was evaluated. Different percentages of the used-solution (20%, 40%, 60%, 80%, and 100% of the target volume) were recirculated to find a proper recirculation volume for maintaining the target nutrient level with the minimum supply of stock solutions. The nutrient saving percentage was determined by comparing the nutrient solution requirement with the open-type aeroponic system and open-field cultivation practices. Reduction of environmental pollution was assessed based on the possible environmental pollutions (i.e., surface water pollution, groundwater contamination, and contaminant deposition in the human body), which could be occurred by the direct discharge of the hydroponic nutrient solution. The minimum amount of stock solutions were required during the 60% used-solution recirculation. The nutrient solution requirement of the recycle-type aeroponic system was almost 3 to 5 times less than the open-type aeroponic system, and 3 to 6 times less than open-field cultivation based on nutrient consumption rates at different growth stages. An open-type aeroponic system might require more nutrient solution than the open-field cultivation practices based on the frequency of nutrient solution supply in the crop root zone. Although, the discharged nutrient solution increased the K+, NO3-, and Ca2+ ion levels a little in the considered surface water reservoir, groundwater, and human body, long-term discharge of the high concentrated hydroponic nutrient solution would be hazardous. The findings of this study showed that the nutrient saving efficiency of a recycle-type crop cultivation system is higher compared to the open-type and conventional cultivation practices, which can minimize the cultivation cost notably, and the environmental pollutions can be reduced significantly through the sensor-based nutrient management.

Solid-state NMR Spectroscopic Analysis of Sweet Cherry Leaves under Different Cultivation Patterns

Solid-state 1H-NMR and 13C-NMR spectroscopy were used to investigate the chemical components of sweet cherry tree leaves under rain-shelter cultivation (RS) and open-field cultivation (CK). The 1H-NMR spectral chemical shifts of RS and CK showed differences in height and integral value. The δ 1–3, δ 3–4, δ 4–6, and δ 6–10 regions were attributed to the hydrogen signals of aliphatic compounds, unsaturated carbohydrate compounds, and aromatic compounds, respectively. Among the four regions, the percentage of signal strength and the integral value of hydrogen signals of RS and CK were 34.25% and 28.34%, 11.64% and 12.26%, 26.71% and 31.06%, 27.4% and 28.34%, respectively. The 13C-NMR results showed that the CK sample had slightly stronger spectral lines and contained slightly more carbon atoms than the RS sample. Sweet cherry leaves contain aromatic and carboxyl carbons, mainly from carboxylic acids, esters, and amides. The alkyl carbons exhibited the lowest ratio, whereas the alkyl and alkoxy carbons were mainly derived from carbohydrates (cellulose, polysaccharides).

Development of short-term evapotranspiration forecasting model using time series method for supporting the precision agriculture management in tropics

To support daily farm management through the environmental challenges, it is necessary to have short-term evapotranspiration forecasting to predict an n-hour step. Evapotranspiration (ET) is the sum of evaporation and transpiration from the soil surface and plant tissue that can be used to assess the water loss behaviour in open-field cultivation. The objective of this study was to develop a short-term evapotranspiration forecasting model using the time series method. The model is based on the Seasonal Autoregressive Integrated Moving Average (SARIMA). The environmental data of air temperature, relative humidity, and solar radiation were observed at Rejeki Tani Yogyakarta from January to August 2014. The ET was estimated using the FAO56 Penman-Monteith. A suitable parameter of non-seasonal autoregressive order (p), the degree of differencing (d), moving average order (q), and their seasonal parameter (P, D, Q)s were investigated to predict 12-hour ahead of ET. As the result, the suitable parameter was SARIMA(2, 1, 2)(1, 1, 1)24. From the six months model validation with the different monsoons, the MAE and RMSE ranged from 0.035636 to 0.063419, and 0.045893 to 0.079961 respectively. The R2 was between 0.8045 and 0.85902. The developed forecasting model can be used to predict the hourly evapotranspiration with acceptable error and accuracy.

Prioritising water disinfection technologies to improve food safety of leafy vegetables

PurposeLeafy vegetables may get contaminated with pathogens through the use of irrigation water during open field cultivation. The main control option to prevent this contamination is the use of disinfection technologies that will reduce the pathogenic load of the irrigation water. Several technologies, either chemical or physical, are available for disinfection, which were gathered from the literature and European Union (EU) projects. The purpose of this paper is to prioritise these technologies.Design/methodology/approachA feasibility study was performed to identify the most promising disinfection technology considering 12 different criteria. A two-tier approach was used in which the technologies were first evaluated based on three criteria: legal status, effectiveness and technology readiness level (TRL). Only the technologies that reached pre-set thresholds for these three criteria were then evaluated in the second tier.FindingsThe evaluation showed that the most promising technologies after the tier-2 evaluation were ultrasound, microfiltration, ultraviolet and ozone. The study showed that the followed approach enabled prioritising disinfection technologies allowing for selecting the most promising technologies that can be tested further on a possible application during primary production to prevent possible food safety issues in leafy vegetables.Research limitations/implicationsThe overview is not an exhaustive list of disinfection technologies available rather only those technologies that seemed promising for application in horticulture were addressed. Some technologies may, thus, have been missed. Nevertheless, a total of 12 single and seven combined technologies were evaluated.Originality/valueThis is the first study that uses a structured approach to prioritise a broad range of possible water disinfection technologies for use at primary production.

INFLUENCE OF TEMPERATURES RISE OVER 48-YEARS ON SULAYMANIYAH AGROECOSYSTEM STRUCTURE AND NEMATODES DISTRIBUTION USING GIS APPLICATION

From a studied to collect data for temperature degrees during 1973 until 2019 there is clear evidence that show climate change is happening in our region. The collected data showed that the average annual temperature rate has raised by almost 1.3°C, the average of warmest year for this period was recordedin 2010and it was 21.55°C.In2016, averagetemperature degree washigh 20.3°C as the global worm rising the lowest temperature in this period was 16.2°C recorded in 1992.Since 1973 until 1985 the average temperature was18.39°C andsince 1986 until 1998 theaverage temperature raised to18.79°C,then since 1999 until 2010 the average temperature raised again to 19.93°C but in period 2011 to 2018 the average temperature raised to20.09°C.The difference between warmest monthly average temperatures and the coldest month of the year orannual range in 1988 was the highest and valued 31.9°C while in year 1973 was the lowest (19.6°C) but the rate for the period 1973 to 2018 was 27.9°C.The absolute annual temperature range or differences between the maximum absolute temperature and the minimum absolute temperature during a year was obvious like in 1973 was the highest (53°C)and in 1987 was the lowest (35°C).Diurnal temperature variation or the daily difference between the maximum and minimum temperatures was limited in winter months almost recorded 6 - 9°C, but in summer months the ranges is bigger almost reported15 - 18°C.Over these years specially from (2008 -2019) soils that affected with plant pathogenic nematodes increaseddramaticallyin the study area witch was within 10km2because of rising temperatures degrees and need to use greenhousesinstead of open field cultivation, these greenhouses numbers influencingon agroecosystem structure for a long terms.From this investigation,and to control plant pathogenic nematodes in the infested greenhouses,farmers used kinds of chemical pesticides that cause damages to the soils and the yieldsas well as changing agroecosystemstructure. Agroecosystem structure for the study area has been changed relatively because of increasing the numbers of greenhousesthat got almost 7000greenhouse causing imbalance in agroecosystem by using a huge amount of water (125m3/greenhouse).

Narrative review of production of antioxidants and anticancer compounds from Bryophyllum spp. (Kalanchoe) using plant cell tissue culture

: For centuries, plants have been widely used in traditional medicine worldwide for the treatment of many diseases. The subgenus Bryophyllum (genus Kalanchoe) have been used in ethnobotanic medicine across America, Africa and Asia. Traditionally, some formulations derived from leaves and roots of Bryophyllum spp. have been applied for the treatment of common illness such as coughs, fever, infections, insect bites, wounds and burns. Phenolic compounds and bufadienolides are the two major families of secondary metabolites identified in several species of the subgenus Bryophyllum. These compounds have gained much attention due to their associated antioxidant and cytotoxic activity, but they are synthetized by plants in fairly limited amounts. In this sense, plant tissue culture (PTC) technology provides a powerful methodology, able to overcome the limitations of low yields associated with conventional open field cultivation of medicinal plants. Several types of PTC methods are routinely employed in plant in vitro propagation, although micropropagation and cell culture are the most common. While micropropagation provides a reliable multiplication procedure, enabling a continuous in vitro production of great amounts of whole medicinal plantlets or just their organs producing the bioactive metabolites, such as their leaves and/or roots; the cell suspension culture procedure allows for the massive production of secondary metabolites using huge bioreactors. In both cases, the addition of biotic and abiotic elicitors and metabolic precursors trigger the bioaccumulation of secondary metabolites through the induction of plant defense mechanisms.

Techno-Economic Feasibility Analysis of a Stand-Alone Photovoltaic System for Combined Aquaponics on Drylands

An open-field cultivation combined-type aquaponic system (OCAS) was developed to effectively utilize saline groundwater and prevent soil salinization while ensuring food production in drylands. To achieve the sustainable food production of the OCAS in power-scarce areas, a stand-alone photovoltaic system (PVS) for the OCAS was designed through a feasibility study of utilizing solar energy to meet its power demand. As a case study, the OCAS was established in La Paz, Baja California Sur, Mexico, with power consumption 22.72 kWh/day and annual average daily global horizontal irradiation (GHI) 6.12 kWh/m2/day, considering the 2017 meteorological data. HOMER software was employed for performance analysis and techno-economic evaluation of an appropriate PVS. Thousands PVS configurations were evaluated in terms of total net present cost (NPC) and levelized cost of energy (COE). The PVS that fulfilled the power demand and had the smallest NPC was proposed, for which the NPC and COE were calculated as $46,993 and $0.438/kWh, respectively. The relationship between its annual power supply and power demand of the OCAS was also analyzed in detail. It was found that the operation hours and the amount of power generation by the proposed PVS were 4156 h and 19,106 kWh in one year. Additionally, it was predicted that the excess power would occur almost every afternoon and reach 43% of the generated power. Therefore, the COE can be further reduced by rationally utilizing the excess power during operation.

Effects of Moderately-Reduced Water Supply and Picking Time on the Chemical Composition of Pickling Cucumber (Cucumis sativus L.) in Open Field Cultivation

As climate change evokes changing precipitation patterns, the cultivation of vegetable crops in open fields might become more difficult in the future. Nowadays, many vegetable growers are already facing relatively long unprecedented precipitation-free periods. In many growing regions, irrigation is only available to a limited extent or not at all, and the cultivated plants will suffer from moderate water stress more often. Therefore, we examined the effects of moderately-reduced water supply on the chemical composition of pickling cucumber, cultivated in an open field and in a separate greenhouse trial. In the field trial, the reduced water supply treatment (RWS) provided 85–90% of the total water amount of the well-watered control treatment (CTR), applying a randomized block design with six replications comprising two consecutive weekly harvest periods. In fruits obtained by cultivation with reduced irrigation, levels of malic acid, calcium, and magnesium significantly increased, while those of phosphate, phosphorous, nitrogen, and iron decreased based on dry matter. Fresh matter-related results additionally revealed a decrease of myo-inositol and zinc, while sugars and total phenols remained unchanged. In the greenhouse experiment, the RWS obtained 60% of the irrigation amount of the CTR. Here, single cucumber compartments (exocarp, mesocarp, and endocarp) were examined. Chemical compositions changed in a similar, but more pronounced, manner as compared to the open field trial. The levels of individual, nutritionally relevant carotenoids in the peel of pickling cucumber, like lutein and β-carotene, were affected by RWS. Regarding the nutritional quality of fresh marketable cucumber fruits, malic acid, certain minerals and trace elements, as well as the carotenoids were shown to be sensitive to moderate water reduction.

Yield and fruit quality of high-tunnel tomato cultivars produced during the off-season in South Texas

The Rio Grande Valley (RGV) of South Texas is one of the most diverse vegetable-producing regions in Texas. Traditionally, tomatoes in the RGV have been grown in open field during the spring and fall, but the production area has declined significantly due to the high pressure of pests and diseases. RGV open-field cultivation during winter is limited to cold-tolerant vegetables such spinach and cabbage due to the risk of cold days and nights. As an alternative, high tunnels offer an environment protected against pests and diseases, wind, and low temperatures. Here, we studied the feasibility of RGV high-tunnel tomato production to identify the planting date, tomato type, and cultivars best suited for producing high-quality tomatoes during winter. The high tunnel maintained temperatures above 21 °C during chilly days without providing additional heat. In addition, whitefly and thrips populations remained low during most of the cropping season, although pesticide control was required at crop establishment to lower their populations. Overall, higher yields were achieved in October compared to November planting and from determinate compared to indeterminate cultivars. Determinate tomato cultivars TAM Hot-Ty, Mykonos, and TAM HT1 transplanted in October produced up to 96.4, 129.13, and 85.98 t/ha, respectively. Among the cultivars tested, TAM Hot-Ty and TAM HT1 possessed the highest concentrations of soluble solids, with ° Brix >5 %. In an organoleptic test, fruits from high tunnel tomatoes were ranked higher than Texas supermarket tomatoes imported from other regions in terms of flavor, color, and overall characteristics. This study demonstrates that tomato high-tunnel production offers a viable alternative to open-field production in South Texas and could provide a source of high-quality locally produced tomatoes to Texas and nearby markets.

Prevalent phthalates in air-soil-vegetable systems of plastic greenhouses in a subtropical city and health risk assessments

Wide use of plastic greenhouses for vegetable production increases human exposure to phthalate (PAEs) through vegetable intake. However, little information is available about distribution of PAEs in air-soil-vegetable systems of plastic greenhouses and PAE estrogenic effects. This study was designed to investigate PAE distributions and corresponding health risk in plastic greenhouses in Guangzhou, a subtropical city in South China. PAEs were prevalent in plastic greenhouses, with sum concentrations of 16 PAE compounds (∑16PAEs) up to 5.76 mg/kg in soils, 5.27 mg/kg in vegetables and 4393 ng/m3 in air. Di (2-ethylhexyl) phthalate, di-isobutyl phthalate, and dibutyl phthalate were predominant compounds. Average concentrations and bioconcentration factor of ∑16PAEs and the predominant PAE compounds in vegetables of greenhouses were higher than those of open fields. Plastic greenhouses exhibited significantly higher air PAE levels than those of open fields due to higher indoor temperature, which enhanced PAE accumulation by vegetables. Both carcinogenic and non-carcinogenic risks of PAEs via dietary and non-dietary exposures for farmers decreased with an order of vegetable > air > soil. Consumption of vegetables from greenhouses resulted in significantly higher estrogenic effects compared to those from open field cultivation. This study emphasizes highly potential health risks of PAEs in air-soil-vegetable systems of plastic greenhouses.