Greenhouse Vegetable Production Research Articles

Accounting for Organizational and Economic Mechanisms in Greenhouse Activities

The article considers a specific area of greenhouse vegetable production, which is an important area of greenhouse farming that significantly affects the availability of plant products and canned vegetables yearly in the Republic of Uzbekistan. In adopting greenhouse vegetable cultivation, certain factors are considered, such as the location of the farm, natural and climatic conditions, and types of farming, that as open field or protected farming. Agriculture is the main pillar of the country’s economy. This work aims to study greenhouse vegetable farming adopted in the country. It also aims to study the technological innovation applied in its operation, its structural and functional organization, and the economic benefits derived from it. The study data were obtained from the statistical database of the World Bank. The data were analyzed based on the descriptive statistics of the factors characterizing the organizational and economic mechanisms of agriculture in the Republic of Uzbekistan. The study results show that the main technology adopted in the country for the proper running of greenhouse farming is greenhouse vegetable clusters, and there is a strong correlation between the organizational and economic indicators of the greenhouse vegetable clusters. It is found that the economic yield of the greenhouse vegetable clusters depends on the patterns in which the clusters are organized, such as the availability of labor, as well as transport routes for transporting products. Adopting the appropriate policies for organizing the clusters could lead to sustainable food security for the population of the country, including the development of agricultural infrastructures, such as road networks, crop storage facilities, access to electricity, foreign investments, domestic loans, etc. The work analyzes the production efficiency and current economic status of farms. It also gives recommendations for improving the production of vegetable crops in the greenhouse.

Modeling Nitrogen Fate and Water and Nitrogen Use Efficiencies under Different Greenhouse Vegetable Production Systems Using the WHCNS-Veg Model.

Quantitative evaluation of the effects of diverse greenhouse vegetable production systems (GVPS) on vegetable yield, soil water consumption, and nitrogen (N) fates could provide a scientific basis for identifying optimum water and fertilizer management practices for GVPS. This research was conducted from 2013 to 2015 in a greenhouse vegetable field in Quzhou County, North China. Three production systems were designed: conventional (CON), integrated (INT), and organic (ORG) systems. The WHCNS-Veg model was employed for simulating vegetable growth, water dynamics, and fates of N, as well as water and N use efficiencies (WUE and NUE) for four continuous growing seasons. The simulation results revealed that nitrate leaching and gaseous N emissions constituted the predominant N loss within GVPS, which separately accounted for 11.5-59.4% and 6.0-21.1% of the N outputs. The order of vegetable yield, N uptake, WUE, and NUE under different production systems was ORG > INT > CON, while the order of nitrate leaching and gaseous N loss was CON > INT > ORG. Compared to CON, ORG exhibited a significant increase in yield, N uptake, WUE, and NUE by 24.6%, 24.2%, 26.1%, and 89.7%, respectively, alongside notable reductions in nitrate leaching and gaseous N loss by 67.7% and 63.2%, respectively. The ORG system should be recommended to local farmers.

Precise Control and Prevention Methods for Whitefly in Greenhouse Vegetables

Trialeurodes vaporariorum Westwood (greenhouse whitefly) are worldwide polyphagous pests of economic importance that damage solanaceous vegetables. Neonicotinoid pesticides and parasitoid Encarsia formmosa Gahan are the main management strategies applied worldwide, but precise control methods in greenhouse vegetables need to be developed to reduce the application amounts of pesticides and improve the suppression of whitefly populations. Therefore, we assessed the indoor acute toxicities and risk assessment of neonicotinoids for T. vaporariorum and E. formosa adults and pupae and compared the control effects of E. formosa and neonicotinoid acetamiprid. According to the acute toxicities results, most neonicotinoid insecticides were more toxic to E. formosa than T. vaporariorum, and pupae were much less susceptible than adults of both species. Moreover, acetamiprid had a low risk effect on E. formosa. Sole application of E. formosa and acetamiprid could effectively control T. vaporariorum, but their combined application resulted in antagonistic effects on the control of T. vaporariorum. The results showed that a combined application or sole use of E. formosa could reduce the use of insecticides, slow down the development of insecticide resistance in whiteflies, and improve the efficiency of controlling the growth of whitefly populations in greenhouse vegetable production.

Integrated Soil–Crop System Management Promotes Sustainability of Intensive Vegetable Production in Plastic Shed Systems: A Case Study in the Yangtze River Basin, China

Excessive fertilizer input, low nutrient use efficiency, soil quality, and environmental degradation hinder greenhouse vegetable production. Integrated agronomic strategies of soil, crop, and nutrient management are needed to sharply improve the vegetable yield and simultaneously maintain sustainable production. A three-season field experiment was conducted from 2015 to 2018, aiming to evaluate the effect of integrated soil–crop system management (ISSM) on the agronomy, environment, and economy of greenhouse vegetable systems in the Yangtze River Basin, China. Three treatments were included in the experiment: (1) farmers’ current practice (FP), based on a local farmers’ survey; (2) soil remediation treatment (SR), the application of soil conditioner and compost fertilizer instead of chicken manure; (3) ISSM, a combination of soil conditioner, reducing plant density, and using formula fertilizer as well as increasing the fertilization times. The results indicated that ISSM (47.7 Mg ha−1) improved the pepper yield by 17% relative to farmers’ current practice (FP, 40.7 Mg ha−1). Soil remediation (SR), as a single approach, mainly made a contribution to improving the yield (by 6.9%) and nutrient use efficiency while reducing apparent nitrogen (N) losses. Higher yields were mainly attributed to increasing the fruit number per plant. On average, apparent N losses were reduced by 245 kg N ha−1 per season for ISSM compared to FP. In addition, higher net profits were obtained under SR and ISSM relative to FP. Overall, both SR and ISSM have advantages for the agronomy, environment, and economy in greenhouse vegetable production, but ISSM would be the optimal choice to achieve higher yields with lower environmental impacts.

Effects of Water Stress and NPK Levels on Growth and Yield Attributes of Greenhouse-Grown Cucumbers

Judicious use of water and nutrients is a key factor for successful off-season vegetable production in greenhouses. This experiment was conducted under plastic tunnels to evaluate the effect of water stress and NPK levels on the growth and yield attributes of greenhouse-grown cucumbers. Effect of three irrigation levels viz., 100%, 80% and 60% of actual crop evapotranspiration (ETc) and three drip fertigation levels, viz., 100%, 80% and 60% of the recommended dose of NPK (RDF) with control (furrow irrigation with 100% RDF) were studied in a randomized complete block design experiment. The study indicated better plant growth, a greater number of fruits per plant and enhancement in the yield under drip irrigation. Among the various treatments, T5 (W80%ETc.F80% RDF) resulted in the highest mean fresh fruit yield (66.7 ton/ha) while the full irrigation treatments T1 (W100%ETc.F100% RDF) and T2 (W100%ETc.F80%RDF) recorded the lowest mean fresh fruit yield of 12.9 t/ha and 13.9 t/ha, respectively, as against 9.6 t/ha for the control plot. Conversely, the fully stressed T7, T8 and T9 treatments reduced the irrigation requirement by 29%, 26% and 21% but the mean cucumber yield was significantly decreased by 40%, 70% and 59%, respectively. These results suggested that drip irrigation has a great scope for the production of off-season vegetables. A water deficit level of 80% ETc with 80% RDF is the most appropriate treatment and optimal level to obtain better yield, quality and profitability of greenhouse-grown cucumbers under scarce water resources.

Vegetable and potato growing in Kazakhstan as the main direction of agricultural production

The goal is to assess the development of potato and vegetable growing and their impact on the state of domestic and regional agricultural markets, to formulate proposals for stabilizing and improving the situation in the near future. Methods – comparative analysis, economicstatistical and structural approaches. Results – the authors note that in order to achieve the required level of food security, it is necessary to increase the volume of cultivation of these products in large agricultural enterprises, which will contribute to the growth of commercial production of vegetables and potatoes of proper quality. The state and potential of vegetable and potato farms, their regional characteristics, formation of vegetable market, and state support for vegetable growing industry at the national level are considered. The issues of regulating cultivation and sale of vegetable products are analyzed, the level of its consumption in the constituent entities of the Republic of Kazakhstan and factors determining it are shown. Monitoring of the areas of potatoes grown in open ground, tools and mechanisms for stimulating their expansion, the share of gross potato harvest for all categories of farms in the republic, the dynamics of prices of agricultural producers and consumer prices was carried out. Taking into account the scientific views and opinions of researchers, analysis of the category “sustainable development” is presented. Conclusions – it is necessary to carry out reclamation measures related to the involvement of agricultural land in circulation for vegetable and potato growing, increase in state support for agricultural producers, as well as funds to reimburse part of costs incurred for production of greenhouse vegetables, and technical re-equipment of production facilities. The implementation of investment projects is important, which will make it possible in the medium term to achieve complete food independence for vegetables and potatoes and ensure an acceptable price environment for their producers and consumers.

Rotary Drum Composting of Organic School Wastes and Compost Valorization

Inappropriate waste disposal imposes significant health risks in densely populated urban environments and schools, necessitating sustainable waste management. Therefore, a study was carried out at Al-Jazaer School, Kuwait, to evaluate rotary drum composting (RDC) of organic school waste comprising used paper, dry leaves, and vegetable food wastes in a 1:4:20 ratio. Feedstock comprising 42% organic school wastes, 42% horse manure, and 16% sawdust produced mature compost with a C:N ratio of 20.55 on the 43rd day of composting. Distinct mesophilic, thermophilic, cooling, and curing phases were observed during composting. Mature compost recorded a moisture content of 54.3%, pH 8.56, EC of 2.71 mS/cm, total nitrogen of 0.77%, total organic carbon of 18.25%, carbon content of 15.86%, and sulfur content of 0.14%. Soilless growing media comprising peat moss, perlite, and rotary drum compost in three proportions (1:1:1, 1:1:2, and 1:1:3), and peat moss, perlite, and commercial organic compost in a 1:1:3 ratio were evaluated for greenhouse vegetable production. The performance of cucumbers (Cucumis sativus cv. Ramos) raised in the lowest proportion of in-house prepared rotary drum compost (1:1:1 ratio) was comparable with that raised in the highest proportion of commercial compost (1:1:3). The study revealed the potential of RDC for decentralized sustainable waste management at the small-community scale and the suitability of compost from school wastes for soilless culture.

Deciphering the microbial functional potential of aeration drip irrigation to enhance soil organic carbon content

Aerated drip irrigation (ADI) is an important practice for promoting soil fertility and crop productivity in greenhouse vegetable production, yet little research has comprehensively investigated the effects on functional traits of carbon (C) cycling microorganisms. In this study, we sought to assess the potential efficacy of the ADI in enhancing soil organic carbon (SOC) content mediated via changes in microbial communities and the expression of genes associated with the carbon cycle. To this end, we adopted a metagenomics approach to compare the effects of ADI treatments with three dissolved oxygen concentrations (10, 15, and 20 mg L-1) during a three-season tomato cultivation experiment in northern China. The results revealed that the 10 mg L-1 treatment led to a significant increase in the abundance of KorA/B genes (associated with the rTCA cycle) in the C fixation pathway, whereas the 15 mg L-1 treatment increased the abundances of cbbL/R and coxL/S genes (associated with the Calvin cycle and carbon monoxide oxidation, respectively). In addition, based on a co-occurrence network analysis, we observed a positive correlation between cbbL and coxS. Interestingly, r-selected microorganisms, such as Proteobacteria and Actinomycetes, characterized by rapid cell multiplication and high biomass production, were identified as the primary contributors to C fixation and were the main predictors of SOC pools. In contrast, the 20 mg L-1 treatment was found to adversely influence C fixation, although enhanced C degradation could be attributed to the breakdown of organic matter by extracellular enzymes secreted by K-selected microorganisms. Collectively, our findings indicate that ADI with dissolved oxygen concentrations ≤15 mg L-1 can promote SOC content by altering the life history strategies of r-selected microorganisms and genes associated with C fixation. These findings will provide valuable insights into agroecosystem irrigation management, specifically in improving soil fertility and promoting sustainable production.

Effects of Biochar-Coated Nitrogen Fertilizer on the Yield and Quality of Bok Choy and on Soil Nutrients

This study was aimed at problems associated with low fertilizer using efficiency, excessive nitrate content of vegetables, and soil degradation in greenhouse vegetable production. A pot experiment was conducted to assess the effects of applying biochar-coated nitrogen fertilizer (BCNF) on the yield, quality, and nitrate content of bok choy (Brassica rapa subsp. Chinensis) as well as on soil nutrients in greenhouses. Four treatments were set up as follows: no nitrogen fertilizer application (BA), chemical nitrogen fertilizer application (CK), biochar-coated nitrogen fertilizer application (BCNF, the amount of nitrogen was equal to that of chemical fertilizer), and reduced biochar-coated nitrogen fertilizer application (D-BCNF, the amount of fertilizer was 80% of BCNF). Compared with the other treatments, BCNF treatment increased chlorophyll content, plant height, maximum leaf length, maximum leaf width, and other biological characters of bok choy. Compared with CK treatment, BCNF treatment increased the fresh weight of bok choy by 14.02%, while reducing the root–shoot ratio and nitrate content by 19.1% and 46%, respectively. It was further found that the application of BCNF could effectively increase the content of soil organic matter; reduce the leaching loss of nitrate nitrogen, exchangeable calcium and magnesium; and effectively improve nitrogen use efficiency. Therefore, the application of BCNF can not only reduce the loss of fertilizer nutrients, promote plant growth, and improve fertilizer utilization, but it can also improve soil nutrients, fix carbon, and reduce emissions. It is a new type of environmental protection fertilizer with application prospects.

Temperature Matters More than Fertilization for Straw Decomposition in the Soil of Greenhouse Vegetable Field

As the largest organic carbon input to agroecosystems, crop straw can solve the problem of soil quality degradation in greenhouse vegetable fields, harmonize the balance between soil nutrients and energy, and improve soil quality to maintain the sustainable production of greenhouse vegetables. However, the microbial mechanism of the straw decomposition process under different temperatures and fertilization treatments in greenhouse vegetable soils has not been clarified. Soil samples were used to investigate the biology of straw decomposition in the soil at three incubation temperatures (15, 25, and 35 °C) through a soil incubation experiment (60 d) under different fertilization treatments. Fertilization treatments for this long-term field experiment included chemical fertilizer (CF), substitution of half of the chemical N fertilizer with manure (CM), straw (CS), or combined manure and straw (CMS). The results showed that soil hydrolase activities tended to decrease with increasing temperature during straw decomposition. Compared with the CF, organic substitutions (CM, CMS, and CS) increased soil β-glucosidase, β-cellobiosidase, N-acetyl-glucosaminidase, and β-xylosidase activities during straw decomposition. Soil CO2 emission rates were the highest at each incubation temperature on the first day, rapidly declining at 25 °C and 35 °C and slowly declining at 15 °C. The soil CO2 cumulative emissions tended to increase with increasing temperature under different fertilization treatments. PCA showed that the responses of soil enzyme activities to temperature at 7, 15, and 30 d of straw decomposition were stronger than those of fertilization. In summary, both fertilization treatment and incubation temperature could influence soil CO2 emissions by affecting soil physicochemical properties and enzyme activities during straw decomposition, whereas incubation temperature had a stronger effect on straw decomposition than fertilization, as indicated by PLS-PM and three-way ANOVA. Considering the influence for fertilization on the straw decomposition process at different incubation temperatures, the straw applications (CMS and CS) were more suitable to temperature changes.

Enhancing Soil Aggregation and Organic Carbon Retention in Greenhouse Vegetable Production through Reductive Soil Disinfestation with Straw and Fertiliser: A Comprehensive Study

In greenhouse vegetable production, reductive soil disinfestation (RSD) effectively mitigates soil-borne diseases, yet its impact on the dynamics of soil organic carbon (SOC) has not been adequately examined. This study investigated the distribution of soil aggregates and the organic carbon retention mechanism following intensive RSD treatment. Greenhouse experiments, including control (CK), wheat straw (RSD), and wheat straw with chemical fertilizer (RSD + NP) treatments, indicated augmentation in the formation of macro-aggregates (>2 mm and 0.25–2 mm) under RSD, particularly in the RSD + NP treatment. Silty clay particles transform into macro- and micro-aggregates. Fourier infrared spectroscopy highlighted the augmentation of carbon-containing functional groups in SOC, with aliphatic carbon accumulating in macro-aggregates and aromatic carbon in silt clay. Laboratory culture experiments employing different C/N ratios (RSD1 with wheat straw, RSD2 with kiwifruit branches) underscored the beneficial impact of low C/N ratio organic matter on coarse and fine macro-aggregate content, mean weight diameter, geometric mean diameter, and reduced silt clay. Low C/N ratios enhance SOC retention in large aggregates, while high ratios stabilise micro-aggregate carbon. This research underscores the severe degradation in continuous greenhouse cropping systems and emphasises RSD’s dual benefits—disease prevention and improved SOC retention. Implementing RSD requires careful consideration of organic material choices, specifically their C/N ratios, as a pivotal factor influencing SOC dynamics.

Religious Attitudes Towards Ethical Problems in the Greenhouse Vegetable Cultivation in Türkiye

The main purpose of this study is to determine the level of influence of religious sensitivity regarding the ethical problems of greenhouse vegetable cultivation and to investigate the possibility of religious contribution to the solution of ethical problems arising on the ground of greenhouse cultivation. Religious sensitivities of greenhouse vegetable growers, where physical conditions are controlled and industrial production is dominant, were analyzed through main categories such as daily life and religion, pesticides and health, genetics and nature. The study aims to provide a background reading of specific moral issues in the context of religious sensitivity analysis.
 The data were collected by means of questionnaires arranged in accordance with the purpose, by interviewing 430 producers growing vegetables in greenhouses within the borders of Antalya province located in the Mediterranean Region of Turkey. An index was created to analyze the religious mentality of greenhouse vegetable growers and to show their religious sensitivity levels in solving ethical problems. The characteristics of the producers, their attitudes and behaviors in the production process are known as the factors that affect the religious sensitivity towards the ethical problems of greenhouse vegetable cultivation. These factors were tested with a multiple linear regression model whose dependent variable was the religious sensitivity index.
 Producers who think that they are praying while doing their work in the greenhouse vegetable production process and quit their job to perform the Friday Prayer have been found to be more religiously sensitive to ethical issues than other producers. Religion was found to be important in the daily lives of the producers and it was stated that religion affected behaviors on the basis of mentality. The level of religious sensitivity was determined to be quite high, that a mistake they made in greenhouse vegetable growing activities would be punished not only in the hereafter but also in this world. This situation shows that in order to overcome the ethical problems in greenhouse vegetable cultivation, the strategies to be followed should be considered within the religious framework. In the linear regression model, it can be said that the producers with high school and undergraduate education levels have higher religious sensitivity to the ethical problems of greenhouse vegetable cultivation compared to the producers with primary education level. Certain experiences of greenhouse vegetable growers may be linked to their general religious attitudes. In this respect, it can be said that the religious sensitivity of the producers, who have been doing greenhouse cultivation for a long time, towards ethical problems is more important than the less experienced ones.
 The religious sensitivity index for greenhouse vegetable cultivation is the first in the literature. The religious sensitivity index, whose relationships are analyzed in the form of daily life and religious perception, genetics and nature, greenhouse vegetable production and the hereafter, chemical spraying and health, non-compliance with the spraying time and seeing the return in life, moral consistency and market conditions, seems to have the potential to guide further studies.

High soil nitrous oxide emissions from a greenhouse vegetable production system in Shouguang, Northern China

In China, the area of greenhouse vegetable production (GVP) has exceeded 4 million ha, accounting for >80% of global GVP systems. Excessive nitrogen (N) fertilization and frequent irrigation have created GVP hotspots of nitrous oxide (N2O) emissions. There are several studies on soil N2O emissions from GVP systems, but all with low-frequency manual sampling, which may have resulted in large uncertainties regarding quantifying N2O emissions. Herein, we utilized an automatic chamber system equipped with 16 channels to measure N2O emissions under common farm practice from a GVP system in Shouguang, Northern China. We measured emissions from both furrows and ridges for 1 year from July 2020 to July 2021. Our continuous monitoring showed that the annual soil N2O emission was 102 kg N ha−1, accounting for 7.6% of the applied N (1338 kg N ha−1). The annual N2O emission from furrows (176 kg N ha−1) was significantly higher than that from ridges (28 kg N ha−1). Large spatial variations in the N2O emissions were observed, ranging from 102 to 273 kg N ha−1 yr−1 for furrows (n = 8) and from 19 to 45 kg N ha−1 yr−1 for ridges (n = 7). In addition, we found that irrigation caused N2O flux pulses from furrows, increasing by 12–396% compared with the level before irrigation. High-frequency measurements using our automatic chamber system provided detailed information on the diurnal and seasonal dynamics of N2O emissions, which could be useful for building more accurate models and developing more effective policies to reduce N2O emissions from global GVP systems.

Suppression mechanism of soilborne diseases by biochar: Immobilization and deactivation of pathogenic enzymes and toxic metabolites

Greenhouse vegetable production aggravates soilborne diseases. Biochar has been recently considered as soil amendment to effectively prevent soilborne diseases. This study evaluates the immobilization and deactivation of pathogen-produced cell wall degrading enzymes (CWDEs) and toxic metabolites (TMs) by biochar to understand the mechanism involved in tomato Fusarium wilt, with activated carbon as the control. The results reveal that cellulase takes shorter time to reach the adsorption equilibrium than pectinase does. The adsorption isotherm of pectinase follows the Langmuir model, and the adsorption isotherm of cellulase follows the Freundlich model. The adsorption capacity of pectinase is greater than that of cellulase on biochar (on activated carbon). The adsorbed enzymes are completely immobilized and observably deactivated. The activity of immobilized pectinase decreases as 43.01 % of the original activity on biochar and 44.91 % on activated carbon. But the activity of immobilized cellulase decreases only as 1.88 % on biochar and 3.89 % on activated carbon. The tomato seedling bioassay analysis demonstrates that the adsorption of CWDEs and TMs is conducive to the reduction of disease severity. However, these established models (or laboratory simulation) cannot explain the enzyme adsorption process of biochar in the real soil, which requires the further exploration in the future.

Leaching and fractionation of phosphorus in intensive greenhouse vegetable production soils.

Greenhouse vegetable production systems use excessive phosphorus (P) fertilizer. This study is set out to look into the P fractionation, mobility, and risk of P leaching in ten greenhouse soils. The mean P concentrations in leachates varied from 0.4 to 1.6 mg l-1 (mean of 30 days of soil leaching). Between 5.7 and 31.0 mg kg-1 of P was leached from soils during 30 days of column leaching. Organic matter (OM) and Olsen-extractable P (Olsen P) correlated strongly with cumulative P leached after 5, 10, 15, 20, 25, and 30 days of leaching. The high correlation between OM and Olsen P with cumulative P leached at 5 days of leaching suggests that in future leaching experiments, the leaching period should be extended to 5 days of leaching. The first two P fractions correlated significantly with the total P leached in the primary days of leaching. The pH had little effect on P leaching but had a significant impact on soluble and exchangeable P fraction, suggesting that P mobility would increase in these calcareous greenhouse vegetable soils as pH rose. The calculated change point (194 mg kg-1) was high, indicating that a high percentage (40%) of the studied greenhouse soils had exceeded the change point. In conclusion, due to the high degree of P saturation and change point in greenhouse vegetable soils, P mobilization is a significant risk, and the findings can be used to provide future direction for fertilizing greenhouse vegetable soils.

Fog Water Collection for Local Greenhouse Vegetable Production in the Atacama Desert

Agricultural production in the Atacama Desert is restricted by extreme aridity and poor soil quality. Between 18° S and 30° S, low stratocumulus clouds regularly cover the southeastern Pacific Ocean reaching the Coastal Cordillera. Thus, marine fog is constantly present in the coastal areas of the desert. Fog can be harvested using fog collectors. However, limited information is available with regards to the variability of fog presence throughout the year and along the coast of the desert. Combining fog water harvest with hydroponic production under greenhouse facilities presents an alternative for sustainable and local fresh food production. In this article, we analyze the potential of fog water collection in two sites (Alto Patache and Falda Verde) distant by about 1000 km within the Atacama Desert. Additionally, in both locations, the environmental conditions within greenhouse structures, the potential energy requirement for environmental conditioning (including the energy production from photovoltaic panels) and the water requirements of vegetable crops under greenhouse conditions were modeled. The annual average of fog water collection registered was 2.9 and 3.3 L per day per m2 in Alto Patache and Falda Verde, respectively. During the most demanding season for crop evapotranspiration, 2.13 m2 of fog collectors can supply the water required for 1 m2 of greenhouse crops. The energy required for water and air pumps in the hydroponic systems can be supplied with photovoltaic systems including eight PV modules and a battery storage capacity of 9.4 kWh. In conclusion, the present study sheds light on the possibilities of massive water collection from fog to be used in local and sustainable food production in the Atacama Desert.

Responses of yield, fruit quality and water relations of sweet pepper in Mediterranean greenhouses to increasing salinity

Increasing salinization of groundwater used for irrigation is a current and growing problem for vegetable production in greenhouses in the Mediterranean Basin. Vegetable growers in this system require clear information of crop response to salinity, particularly of threshold values. For sweet pepper in Mediterranean greenhouses, this work (i) evaluated the effect of increasing salinity on various parameters of crop yield, fruit quality and plant water relations, and (ii) determined threshold and slope values for the Maas and Hoffman (M&H) model. Sweet pepper was grown with nutrient solutions (ns) with electrical conductivities (EC) of 2.5 (T1), 3.5 (T2), 4.5 (T3), 5.5 (T4), 6.5 (T5) and 7.5 (T6) dS m−1. There were substantial and statistically significant reductions in total and marketable yield, dry matter production (DMP) and average fruit weight, with increasing salinity. In treatment T4 (ns of 5.5 dS m−1), the respective reductions for these parameters, compared to T1 (ns of 2.5 dS m−1), were 37%, 37%, 47%, 52% and 30%. Applying the M&H model, soil solution EC threshold (ECsst) values for total and marketable yield were 4.8 and 5.0 dS m−1. The respective slope values were − 8.0 and − 12.0%/dS m−1. The more rapid decline in marketable yield was influenced by a large increase in the incidence of blossom end rot (BER) with increasing salinity. In treatment T1, 25% of discarded fruit had BER which increased to 70% in T6. Average fruit size was affected by salinity, but fruit number was not. Most fruit quality parameters were unaffected by increasing salinity. However, fruits were more red and more yellow. Leaf water potential (ΨW), leaf osmotic potential (ΨO), stomatal conductance (gS) and leaf turgor potential (ΨP) followed the Maas and Hoffman model, with ΨW, ΨO and gS declining and ΨP increasing after the EC threshold value. The ECsst value for ΨW was 5.0 dS m−1, and for ΨO, gS and ΨP was 5.6–5.8 dS m−1. Considering all data, an ECsst value of 5.0 dS m−1 is suggested for sweet pepper grown in Mediterranean greenhouses.

The environmental and socioeconomic benefits of optimized fertilization for greenhouse vegetables

China produces more than half of global vegetables with greenhouse farms contributes approximately 35 % to the country's overall vegetable supply. The average nitrogen (N) application rate of greenhouse vegetable production exceeds 2000 kg N ha−1 yr−1, considerably contributing to global agricultural GHG emissions and reactive N (Nr) losses. Optimizing the N fertilizer utilization in greenhouse vegetable production is essential for mitigating environmental pollution and promoting sustainable development nationally and globally. In this study, we estimated the N footprint (NF), social costs (SC, which includes ecosystem and human health damage costs caused by Nr losses to the environment) and net ecosystem economic income (NEEI, which balances between the fertilizers input cost, yield profit, and social costs) of different greenhouse vegetables (tomato, pakchoi, lettuce, cabbage) under farmers' practice (FP) and reduced fertilization treatment (R). Results showed that compared with FP, the NF of tomato, pakchoi, lettuce and cabbage in the R treatment decreased by 61 %, 29 %, 46 % and 36 %, respectively, and the social costs were decreased by 60 %, 48 %, 57 % and 50 %, respectively. On the regional scale, the reduction in N fertilizer use for greenhouse vegetables in Beijing only could save the fertilizer input cost by 1–5 million USD, and avoided SC would increase by 1–14 million USD. As a result, this increased the NEEI by 2–19million USD. This study has demonstrated that adopting reduced fertilization practices represents a cost-effective measure that not only ensures yields but also decrease social costs, NF, and improve the benefits to help achieve sustainable development of greenhouse vegetable production.

Microbial mechanism of biochar addition to reduce N2O emissions from soilless substrate systems

The soilless peat-based substrate partially solves the global soil problem in greenhouse vegetable production. However, it still produces serious N2O emissions due to the application of nutrient solutions. The pyrolysis biochar is regarded as an effective measure to reduce soil N2O emissions. However, the effect and mechanism of biochar on N2O emissions from the soilless substrate remain unknown. Therefore, this study set up six treatments by adjusting the ratio of biochar addition of peat-based substrate: 0% (0BC), 2% (2BC), 4% (4BC), 6% (6BC), 8% (8BC) and 10% (10BC) (v/v). The results showed that compared to the control treatment, N2O emissions reduced by 81%, 71%, 51%, 61%, and 75% in the 2BC, 4BC, 6BC, 8BC and 10BC treatments, respectively. In addition, lettuce yield increased by 10% and 7% in the 2BC and 4BC treatments and decreased by 0.5%, 4% and 6% in the 6BC, 8BC and 10BC treatments, respectively. Combining stable isotope technology, qPCR analysis and high-throughput sequencing, five microbial pathways of N2O production, including bacterial and archaea nitrification (BN and AN), denitrification performed by fungi, denitrifier bacteria and nitrifier bacteria (FD, DD and ND), were roughly distinguished. In addition, the extent of N2O reduction was obtained by δ18O vs.δ15NSP map. For all treatments, overall, the DD process (over 50%) was the main process of N2O production and reduction, while ND and AN processes were almost negligible (less 5%). In detail, the decrease of N2O emissions was caused by decreasing the contribution of FD in the 6BC, 8BC and 10BC treatments and reducing the contribution of BN in the 0BC and 2BC treatments. In addition, biochar addition increased the extent of N2O reduction to N2. In summary, the 2% biochar addition presented the greatest extent of N2O reduction to N2 (83%) and the lowest N2O emissions as well as the highest lettuce yields and nitrogen utilization efficiency. Therefore, 2% biochar is deemed the most optimal addition to the peat-based substrate.

Prescriptive-Corrective Irrigation and Macronutrient Management in Greenhouse Soil-Grown Tomato Using the VegSyst-DSS v2 Decision Support Tool

This work relates to greenhouse vegetable production in soil in Almeria, Spain. The prescriptive–corrective management (PCM) of irrigation and fertilization (N, P, K, Ca, and Mg) was evaluated. PCM combined recommendations (prescriptive management) for irrigation and nutrients made with the VegSyst-DSS v2, a decision support system, with monitoring (corrective management) using tensiometers (for irrigation) and petiole sap analysis (for nutrients). PCM was compared with conventional farmer management (CONV). The VegSyst-DSS v2 recommends applied nutrient concentrations considering simulated crop uptake, available soil nutrient supply, and evapotranspiration (ETc). This study was conducted with soil-grown tomato in a plastic greenhouse. Nutrients were applied in nutrient solution via drip fertigation. Compared to CONV management, PCM reduced irrigation by 25%, N, K, and Mg application by 40%, Ca by 58%, and P by 85%. There were no significant differences between treatments in fruit production and quality, despite appreciable reductions in irrigation and nutrient application. An economic analysis indicated that in this 7-month tomato crop, PCM compared to CONV management was associated with a financial saving of 1611 € ha−1. These results showed that by using prescriptive–corrective fertigation management, based on the VegSyst-DSS v2, considerable savings can be achieved in water and nutrient (N, P, K, Ca, and Mg) inputs to greenhouse tomato without compromising production. This can reduce farmer costs and the environmental impact associated with these greenhouse production systems.