Vasectomy and photoperiodic regimen modify the protein profile, hormonal content and antioxidant enzymes activity of ram seminal plasma

This work aimed to determine the contribution of the testis and epididymis and the effect of the photoperiodic regimen on ram seminal plasma (SP). Semen was collected from 15 mature rams located in an equatorial (Colombian Creole and Romney Marsh, eight intact and two vasectomized) or a temperate climate (Rasa Aragonesa, three intact and two vasectomized). SP proteins were analyzed by Bradford, SDS-PAGE and difference gel electrophoresis (DIGE). Melatonin and testosterone concentrations were quantified by ELISA, and activity of glutathione peroxidase (GPx), glutathione reductase (GRD), and catalase by enzymatic assays. Vasectomy increased protein concentration and the intensity of high molecular weight bands (p < 0.001), with no differences between breeds. DIGE revealed the absence of six proteins in vasectomized rams: angiotensin-converting enzyme, lactotransferrin, phosphoglycerate kinase, sorbitol dehydrogenase, epididymal secretory glutathione peroxidase and epididymal secretory protein E1. Vasectomy also decreased melatonin concentrations in seasonal rams, and testosterone in all of them (p < 0.001), but did not affect antioxidant enzyme activity. Equatorial rams showed lower melatonin and testosterone concentration (p < 0.01) and catalase, but higher GPx activity (p < 0.05). In conclusion, vasectomy modifies the protein profile and hormonal content of ram seminal plasma, whereas the exposure to a constant photoperiod affects hormonal concentration and antioxidant enzymes activity

Bacteria-inducing legume nodules involved in the improvement of plant growth, health and nutrition

Bacteria-inducing legume nodules are known as rhizobia and belong to the class Alphaproteobacteria and Betaproteobacteria. They promote the growth and nutrition of their respective legume hosts through atmospheric nitrogen fixation which takes place in the nodules induced in their roots or stems. In addition, rhizobia have other plant growth-promoting mechanisms, mainly solubilization of phosphate and production of indoleacetic acid, ACC deaminase and siderophores. Some of these mechanisms have been reported for strains of rhizobia which are also able to promote the growth of several nonlegumes, such as cereals, oilseeds and vegetables. Less studied are the mechanisms that have the rhizobia to promote the plant health; however, these bacteria are able to exert biocontrol of some phytopathogens and to induce the plant resistance. In this chapter, we revised the available data about the ability of the legume nodule-inducing bacteria for improving the plant growth, health and nutrition of both legumes and nonlegumes. These data showed that rhizobia meet all the requirements of sustainable agriculture to be used as bio-inoculants allowing the total or partial replacement of chemicals used for fertilization or protection of crops

Airflow and microclimate patterns in a one-hectare Canary type greenhouse: an experimental and CFD assisted study

This study presents an analysis of air circulation and microclimate distribution during daytime in a 1-hectare Canary type tomato greenhouse in the coastal area of southern Morocco. The investigation of the climate inside the greenhouse is based on a numerical simulation using a finite volumes method to solve the mass, momentum and energy conservation equations. The main novelty of this simulation lies in the realism of the 3D modelling of this very large agricultural structure with (i) a coupling of convective and radiative exchanges at the surface of the plastic roof cover, (ii) simulation of the dynamic influence of the insect screens and tomato crop on airflow movement, using the concept of porous medium, (iii) simulation, in each grid cell of the crop canopy, of the sensible and latent heat exchanges between the greenhouse air and the tomato crop, and (iv) detailed simulation of climate parameters in a 1-hectare real-scale commercial greenhouse. The model simulations were first validated with respect to temperature and relative humidity fields measured inside the experimental greenhouse for fairly steady-state outside conditions marked by a prevailing sea breeze around the solar noon. A good agreement was observed between the measured and simulated values for inside air temperatures and specific humidity. It was next used for exploring the details of the inside air temperature and humidity fields and plant microclimates and transpiration fluxes throughout the greenhouse space. Simulation for a wind direction perpendicular to the side and roof openings shows that the insect screen significantly reduced inside air velocity and increased inside temperature and humidity, especially in the vicinity of the crop canopy. It revealed the details of the flow field within the greenhouse. At the windward end of the greenhouse, the flow field was marked by a strong windwise air current above the tomato canopy which was fed by the wind ward side vent, and a slow air stream flowing within the tomato canopy space. Then, from the first third of the greenhouse to the leeward end, the flow field was marked by the combination of wind and buoyancy forces, with warmer and more humid inside air which was evacuated through the upper roof vents, while colder and dryer air was penetrated through the upper roof vent openings. Based on these simulations, design studies of the greenhouse crop system were performed to improve inside air temperature and humidity conditions by simple modifications of orientation of the crop row

Increasing the height and multiplying the number of spans of greenhouse: how far can we go?

International audienceThis study is principally based on predicting the consequences on the microclimate of changing greenhouse design. Several variations on the greenhouse design have been described and examined, i.e. the number of spans and gutter height. Climate investigations were based on numerical simulations using the CFD model and included the dynamic effect of the crop on the flow as well as the subsequent heat and mass exchanges. The results show: (i) that the structural design elements, such as the height of the greenhouse and the number of spans, have significant consequences on climate performance; (ii) that we cannot indefinitely increase the height and the number of spans of greenhouses; (iii) that increasing the volume of the greenhouse raises heat requirements and thus the economic profitability of this kind of investment is debatable

Computational fluid dynamics modelling of the microclimate within the boundary layer of leaves leading to improved pest control management and low-input greenhouse

This work aims at using the Computational Fluid Dynamic (CFD) approach to study the distributed microclimate in the leaf boundary layer of greenhouse crops. Understanding the interactions in this microclimate of this natural habitat of plant pests (i.e., boundary layer of leaves), is a prerequisite for their control through targeted climate management for sustainable greenhouse production. The temperature and humidity simulations, inside the greenhouse, were performed using CFD code which has been adapted to simulate the plant activity within each mesh in the crop canopy. The air temperature and air humidity profiles within the boundary layer of leaves were deduced from the local surrounding climate parameters, based on an analytical approach, encapsulated in a Used Defined Function (UDF), and dynamically linked to the CFD solver, a work that forms an innovative and original task. Thus, this model represents a new approach to investigate the microclimate in the boundary layer of leaves under greenhouses, which resolves the issue of the inaccessibility of this area by the conventionnel measurement tools. The findings clearly showed that (i) contrarily to what might be expected, the microclimate parameters within the boundary layer of leaves are different from the surrounding climate in the greenhouse. This is particularly visible during photoperiods when the plant’s transpiration activity is at its maximum and that (ii) the climatic parameters in the leaf boundary layer are more coupled with leaf surfaces than with those of greenhouse air. These results can help developing localized intervention strategies on the microclimate within boundary layer of plant leaves, leading to improved and sustainable pest control management. The developed climatic strategies will make it possible to optimize resources use efficiency. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Computational study of thermal performance of an unheated canarian-type greenhouse: influence of the opening configurations on airflow and climate patterns at the crop level

International audienceThe increasing cost of electricity often drives the famers of the countries of the southern shore of the Mediterranean, to adopt the natural ventilation in order to provide greenhouse aeration. The roof and sidewall vents are opened to allow the excess heat to escape and cooler outside air to enter during daytime. During night time, these openings are used mainly to regulate the excess humidity in greenhouse which causes damage on plants due to the development of Botrytis cinerea. This paper presents a computational fluid dynamic (CFD) comparative study of the effect of these roof and sidewall ventilation openings on airflow circulation and diurnal and nocturnal greenhouse climate distribution to assess their effect. The investigation was conducted in a one hectare canarian-type greenhouse, the most widely used in Morocco, with a mature tomato crop. The simulations were performed with the CFD model based on solving partial differential equations, which represent conservation laws for the mass, momentum, and energy, using CFD finite volume method (FVM). This CFD model takes into account the virtual crop as a porous medium using the Darcy-Forchheimer model restricted to its inertial terms. Simulation results show that opening configurations strongly affects the airflow circulation under the studied greenhouse, which can generate a heterogeneous climate at the canopy level, especially during daytime. Results have illustrated also that there is a reverse flow from the leeward end to windward end part of the greenhouse at the crop level. Closing the north-south sidewall ventilation openings contributes significantly to the inside air velocity increase which can decrease the diurnal air temperature at the crop level. Conversely, during night-time, climate distribution at the crop level is homogeneous on the whole greenhouse

Computational fluid dynamics modelling of the microclimate within the boundary layer of leaves leading to improved pest control management and low-input greenhouse

This work aims at using the Computational Fluid Dynamic (CFD) approach to study the distributed microclimate in the leaf boundary layer of greenhouse crops. Understanding the interactions in this microclimate of this natural habitat of plant pests (i.e., boundary layer of leaves), is a prerequisite for their control through targeted climate management for sustainable greenhouse production. The temperature and humidity simulations, inside the greenhouse, were performed using CFD code which has been adapted to simulate the plant activity within each mesh in the crop canopy. The air temperature and air humidity profiles within the boundary layer of leaves were deduced from the local surrounding climate parameters, based on an analytical approach, encapsulated in a Used Defined Function (UDF), and dynamically linked to the CFD solver, a work that forms an innovative and original task. Thus, this model represents a new approach to investigate the microclimate in the boundary layer of leaves under greenhouses, which resolves the issue of the inaccessibility of this area by the conventionnel measurement tools. The findings clearly showed that (i) contrarily to what might be expected, the microclimate parameters within the boundary layer of leaves are different from the surrounding climate in the greenhouse. This is particularly visible during photoperiods when the plant’s transpiration activity is at its maximum and that (ii) the climatic parameters in the leaf boundary layer are more coupled with leaf surfaces than with those of greenhouse air. These results can help developing localized intervention strategies on the microclimate within boundary layer of plant leaves, leading to improved and sustainable pest control management. The developed climatic strategies will make it possible to optimize resources use efficiency. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Assessment and comparison of the solar radiation distribution inside the main commercial photovoltaic greenhouse types in Europe

The application of the photovoltaic (PV) energy to the European greenhouse industry has led to installations designed to maximise the energy production but detrimental for the greenhouse crops, due to the effect of shading of the PV panels on the roof. To assess these issues, the first step is to characterize the PV greenhouse microclimate, especially in terms of solar radiation at canopy level. After a comprehensive review of the current state-of-art of the PV greenhouse sector, four representative commercial PV greenhouse types are compared, with a percentage of the area covered with PV panels (PV cover ratio) ranging from 25% to 100%. The aim is to define the general relations between the main design parameters (PV cover ratio, greenhouse height and orientation, checkerboard pattern) and the available solar radiation, to provide original information on the design of next-generation PV greenhouses with improved agronomic sustainability. The yearly global radiation decreased averagely by 0.8% for each additional 1.0% PV cover ratio and increased by 3.8% for each further meter of gutter height. The N-S orientation increased the average cumulated global radiation on the greenhouse area by 24%, compared to the E-W orientation. Both the checkerboard pattern and the N-S orientation improved the uniformity of light distribution. All PV greenhouse types are provided with light distribution maps to evaluate the light variability on the greenhouse area. The light distribution is crucial to support adequate agronomic plans for both preexisting and new PV greenhouses, aiming to sustainable mixed systems for both energy and crop production