Sustainable Irrigation Management of Ornamental Cordyline Fruticosa “Red Edge” Plants with Saline Water

The aim of this work was to analyze the influence of the salinity of the nutrient solution on the transpiration and growth of Cordyline fruticosa var. “Red Edge” plants. A specific irrigation management model was calibrated with the experimental data. An experiment was performed with four treatments. These treatments consisted of the application of four nutrient solutions with different electrical conductivity (ECw) levels ranging from 1.5 dS m−1 (control treatment) to 4.5 dS m−1. The results showed that day-time transpiration decreases when salt concentration in the nutrient solution increases. The transpiration of the plant in the control treatment was modelled by applying a combination method while the effect of the salinity of the nutrient solution was modelled by deriving a saline stress coefficient from the experimental data. The results showed that significant reductions in plant transpiration were observed for increasing values of ECw. The crop development and yield were also affected by the increasing salinity of the nutrient solution. A relationship between the ECw and the relative crop yield was derived

THERMAL ENVIRONMENT MODELING AND OPTIMIZATION OF GREENHOUSE IN COLD REGIONS

Thermal simulation models for the time-dependent heating requirement of greenhouses are very important for the evaluation of various energy-saving technologies, and energy-efficient design of greenhouses based on local climates. A quasi-steady state thermal model “GREENHEAT” was developed using the programing language MATLAB for simulation heating requirement in conventional greenhouses. The model could predict the hourly heating requirement based on the input of hourly weather data, indoor environmental parameters, and physical and thermal properties of greenhouse building materials. The model was validated with measured data from a commercial greenhouse located in Saskatoon, Canada, and the monthly average error in prediction was found to be less than 5.0%. This study also reviewed various energy-saving technologies used in greenhouses in cold climate, and the GREENHEAT model allowed selections of commonly used ones in the simulation. The GREENHEAT model was used for evaluating the impact of various geometrical parameters on the heating requirement of the single span and multiple-span conventional greenhouses located in Saskatoon. Results showed that the east-west oriented gable roof greenhouse could be more energy-efficient for the multi-span gutter connected greenhouse whereas quonset shape as a free-standing single span greenhouse. The large span width could be beneficial for the single-span greenhouses, but the impact of increased span width could be negligible on the heating demand of multi-span greenhouses. The model was also used for an economic feasibility analysis of year-round vegetable production (tomato, cucumber, and pepper) in northern Saskatchewan, and tomato was found to be the most economical vegetable as compared to the cucumber and pepper. Another heating simulation model CSGHEAT was developed to estimate of the supplemental heating requirement of mono-slope Chinese-style solar greenhouses (CSGs). This model is also a quasi-steady state thermal model using the programming language MATLAB, and it can simulates the hourly heating requirement of CSGs. The model was validated with experimental data from a CSG located in Winnipeg, Manitoba. The average error for prediction of the hourly heating requirement was found to be less than 8.7%. The model sensitivities to various geometrical and thermal parameters were studied. The results indicated that the thermal properties of cover, thermal blanket, and parameter insulation were the most important design parameters in CSGs. Finally, the heating requirement in CSGs was modeled using TRNSYS simulation tool, and the predictions were compared with that of CSGHEAT. The result indicated that TRNSYS had serious limitations for modeling of greenhouse thermal environment, thereby high uncertainties could occur, thus was not suitable for greenhouse simulation

Ecophysiological and agronomic response of horticultural crops grown under screens in a mediterranean climate

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Este trabajo atañe a la investigación de los efectos de mallas de protección, como mallas de sombreo o mallas anti-insectos, sobre el microclima y la respuesta fisiológica y agronómica de cultivos hortícolas. Un conocimiento más detallado de estos efectos debería conducir a un diseño óptimo de las estructuras de protección y a la mejora de las técnicas de cultivos en los sistemas de producción utilizando estas estructuras. En este trabajo, ensayos comparativos de diferentes tipos de mallas han sido llevados a cabo para evaluar sus efectos en el microclima y la respuesta de dos especies (pepino y pimiento). Los resultados más relevantes son los siguientes: - Un sombreado moderado durante el periodo estival es benéfico para los cultivos. (Publicación 1). Un sombreo interno ha producido efectos positivos en el microclima bajo invernadero y en el comportamiento fisiológico de cultivos de pepino. Las severas condiciones de estrés encontradas en el invernadero sin sombreo fueron sustancialmente reducidas bajo el invernadero sombreado, como demostrado por el incremento de la conductancia estomática de las plantas cultivadas bajo sombreo. - Las estructuras de malla mejoran la eficiencia de uso de la luz (Publicación 2). Se ha demostrado que, dentro del intervalo de reducción de transmisión correspondiendo a diferentes tipos de malla (de 20 a 40 %), la magnitud y la tendencia temporal de la asimilación neta de CO2 de plantas de pimiento fueron poco afectadas con respecto a las plantas cultivadas en el exterior, conduciendo a un aumento substancial de la eficiencia de uso de la luz. - Las estructuras de mallas incrementan la productividad de los cultivos de pimiento (Publicación 3). Nuestros resultados sugieren que la naturaleza más difusa de la radiación bajo estructuras de malla es probablemente la causa del rendimiento superior de las plantas cultivadas bajo estas estructuras. - Un modelo para predecir los requerimientos de agua de cultivos bajo malla (Publicación 4). Un método original para la estimación de la evapotranspiración de referencia de cultivos bajo malla ha sido desarrollado y validado. Este estudio aporta argumentos científicos y técnicos a la conclusión que las estructuras de malla con un diseño optimizado y con transmisión y porosidad adecuada constituyen uno de los medios más económicos y sostenibles de incrementar la productividad de los cultivos hortícolas en regiones Mediterráneas.[ENG] This doctoral dissertation has been presented in the form of thesis by publication. The general scope of this work was to investigate the effect of crop covering-nets, like shade-nets or insect-proof screens, on the microclimate and crop response in protected cultivation. Knowledge and modelling of the effects of screens on microclimate should lead to a better design of the screens and adapted crop techniques, in order to ultimately increase growers¿ profitability with minimum impact on the environment. In this study, comparative experiments with shading materials differing in shading intensity and porosity were carried out to assess their effects on microclimate and crop (cucumber and sweet pepper) behaviour. The most relevant findings can be summarised as follows: - Moderate shading is beneficial to crops during the warm season (Publication 1). Shading by internal screen has a beneficial effect on both the greenhouse microclimate and crop behaviour under Mediterranean summer conditions. The strong stress conditions experienced by a cucumber crop under no shading were reduced under shading as demonstrated by the enhanced crop stomatal conductance. - Screenhouses improve light use efficiency (Publication 2). It was demonstrated that, within the relatively large range of shade provided by the tested screenhouses (ca. from 20 to 40 %), the magnitude and temporal trend of net CO2 assimilation were only slightly affected with respect to natural light conditions, therefore leading to a substantial increase in leaf light-use efficiency of sweet pepper plants. - Screenhouses increase yield with respect to outside crops (Publication 3). The results suggested that the more diffuse radiation regime prevailing under screenhouse is likely to be at the root of the higher sweet pepper crop performances observed under the screenhouses. - A model to predict screenhouse-crops water requirements (Publication 4). An original method to estimating the reference evapotranspiration of screenhouse-grown crops has been developed and validated. This work provides scientifically and technically-based arguments to support the conclusion that a well-designed screenhouse, having the appropriate optical properties and porosity, is one of the most environmentally and economically-sustainable structures for increasing the productivity of horticultural crops in Mediterranean regions.Las referencias de las publicaciones son las siguientes: Publication 1: Kitta, E., Katsoulas, N., Savvas, D., 2012. Shading effects on greenhouse microclimate and crop transpiration in a cucumber crop grown under Mediterranean conditions. Applied Engineering in Agriculture, 28(1):129-140. Publication 2: Kitta, E. Katsoulas, N. Kandila, A. González-Real M.M., Baille Α., 2014. Photosynthetic acclimation of sweet pepper plants to screenhouse conditions. HortScience, 49(2): 166-172. Publication 3: Kitta, E., Baille, A., Katsoulas, N., Rigakis, N., González-Real, M.M., 2014. Effects of cover optical properties on screenhouse radiative environment and sweet pepper productivity. Biosystems Engineering, 122: 115-126. Publication 4: Kitta, E., Baille, A., Katsoulas, N., Rigakis, N. 2014. Predicting reference evapotranspiration for screenhouse-grown crops. Agricultural Water Management. 143 : 122–13.Universidad Politécnica de CartagenaPrograma de doctorado Técnicas Avanzadas en Investigación y Desarrollo Agrario y Alimentario (TAIDA

Advances in irrigation management in greenhouse cultivation

The advantages of greenhouse include the ability to secure better conditions than outdoor environment for crop growth and development, increased off-season production and autonomy from external weather conditions. This chapter provides an up-to-date critical overview of scientific advances in irrigation management for greenhouse vegetables and ornamentals. The chapter presents a technical design of a typical greenhouse irrigation system, before covering water balance and crop evapotranspiration techniques as well as the use of high-tech moisture sensors for irrigation scheduling. In the context of enhancing the water use efficiency of greenhouse crops, the chapter also discusses innovative management practices such as biostimulants and grafting. Finally, the chapter concludes by looking ahead to future prospects and research breakthroughs

Fertigation Scheduling in Hydroponics System for Cucumber (Cucumis Sativus L.) Using Artificial Neural Network and Genetic Algorithms

A computer program for fertigation scheduling in a hydroponics system has been developed using Artificial Neural Network (ANN) and Genetic Algorithms (GA). The ANN model was used to establish the relationship between the environmental factors and outflow volume of fertigation in a hydroponics system for cucumber. The result showed that the predicted outflow volume agreed well with those of the measured values. The correlation coefficients (R2) between the predicted and measured values were 0.9673, 0.9432, and 0.8248 for vegetative, flowering and maturation stages, respectively. Optimum schedules for vegetative, flowering, and maturation stages were in a good coincidence at R2 of 0.8808 with the amount of fertigation required by the plants as calculated using the empirical method

Modelling transpiration of greenhouse gerbera (Gerbera jamesonii H. Bolus) grown in substrate with saline water in a Mediterranean climate

Gerbera plants were grown in semi-closed rockwool culture under greenhouse conditions in different seasons in a Mediterranean climate. The plants were irrigated using either fresh (FW; 1.0 mol m−3NaCl)or moderately saline (SW; 9.0 mol m−3NaCl) water. In autumn, NaCl concentration did not influence significantly plant growth, flower production and transpiration (E), which instead were reduced in springin the plants irrigated with SW. In both seasons, water salinity did not affect leaf stomatal resistance (rl),which was determined by the inversion of the Penman–Monteith (PM) equation or measured with a diffusion porometer. The PM formula and two regression equations were calibrated and validated for estimating the hourly rate of daytime transpiration (Ed); a regression model was also fit to nocturnal transpiration (En). Regression models predicted Edas a function of vapour pressure deficit (VPD) and/or the radiation intercepted by the canopy. Leaf area index (LAI), which is required by all the equations, was modelled as function of crop thermal time (i.e. growing degree days). The PM model predicted Ed using a constant value of rl. Model calibration and validation were performed using independent data sets. The irrigation with FW or SW did not require a different calibration of transpiration models. Both PM formula and regression equations provided accurate estimates of Ed; fitted equations explained between 80% and96% of the variance in measured Ed. A linear regression of En against (LAI·VPD) accounted for 92% of measured En

Effect of irrigation regime and application of kaolin on yield, quality and water use efficiency of tomato

Modern agriculture is faced with two tasks: (1) to produce enough food for a growing global population, and (2) to ensure satisfactory crop quality while using water resources efficiently. A study of the effect of kaolin on the yield, quality and water use efficiency of tomato (Lycopersicon esculentum Mill.), grown under different irrigation regimes, is reported in the paper. The research was conducted in an open field with carbonate chernozem soil, at Stara Pazova (40 km north of Belgrade, Serbia). It lasted for three years (2011, 2012, and 2013). The experimental setup was a two-factorial, completely random block system, with three replications. The first factor was the irrigation regime and the second the application of kaolin. Two irrigation treatments were studied: (a) full irrigation (F), covering 100% of ETc (crop evapotranspiration), and (b) deficit irrigation (D) at 50% of ETc. The kaolin treatments were: (a) control treatment, without kaolin (C) and treatment with a 5% suspension of kaolin (K). On average, the highest fresh tomato fruit yields were achieved under full irrigation, with kaolin (FK) (21.0 kg m(-2)). The FK treatment also resulted in the greatest dry weight of the fruits (1.1 kg m(-2)). The average fruit weight was rather uniform and ranged from 71.7 g with DC to 75.4 g with DK. The average sugar and lycopene content was quite uniform over the study period, while the irrigation regime had a significant effect on the average organic acid content and total antioxidant activity. Deficit irrigation treatments resulted in a higher organic acid content and higher total antioxidant activity than full irrigation. The application of kaolin had a greater effect of the water use efficiency of tomato than the irrigation treatment.This is the peer-reviewed version of Djurović, N., Ćosić, M., Stričević, R., Savić, S.,& Domazet, M.. (2016). Effect of irrigation regime and application of kaolin on yield, quality and water use efficiency of tomato. in Scientia Horticulturae Elsevier, Amsterdam., 201, 271-278. [https://doi.org/10.1016/j.scienta.2016.02.017 conv_5711