Effects of Protected Environments on Plant Biometrics Parameters

Edilson Costa1, Paulo Ademar Martins Leal2 and Carolina de Arruda Queiroz3

1Professor Ph. D., Agricultural Engineer, State University of Mato Grosso do Sul-UEMS, Unit of Aquidauana 2Professor Ph. D., Agricultural Engineer, University of Campinas,

College of Agricultural Engineering 3MSc in progress, Agronomist, Graduate Program in Agronomy,

Crop Area, UEMS / Aquidauana-MS

Brasil

1. Introduction

There is a high correlation between the type of greenhouse used for crop production with the system used for its production, especially with the type of container and substrate used. The same protected environment may present different responses in plant biometric parameters depending on the container volume and also the chemical and physical characteristics of a particular substrate. This relationship is expressed in greater or lesser accumulation of plant biomass.

Besides of the substrate and container type, other studies seek to improve the crop yield potentials and cropping systems associated with environmental control techniques, such as cooling and/or heating systems, use of CO2 for atmospheric enrichment, color screens systems and automated control of the atmospheric parameters.

Protected environments for crop production are generally constructed of low density polyethylene film (greenhouses), and shading screens, such as monofilament screens and aluminized thermal reflective screens (are widely used. In these types of environments growing in containers is preferred because it allows for better management of both water and nutrients (Grassi Filho & Santos 2004).

Changes in the microclimate inside the greenhouses caused by the use of polyethylene result in modification of the influence of air temperature, relative humidity and solar radiation on plant growth and development, and these are dependent on the intensity, duration and quality of solar radiation (Beckmann et al., 2006; Scaranari et al., 2008). These changes affect the plants physiology (Chavarria et al., 2009), and minimize the incidence of fungal diseases and therefore application of pesticides (Chavarria et al., 2007). In vineyards, where only the rows were covered with polyethylene film, Cardoso et al. (2008) found a reduction in evaporative demand.

According to Sganzerla (1987), the advantages that the greenhouses can provide to the protected plants are numerous, as long as these facilities are correctly used. Among these

advantages some can be highlighted including harvesting crops of the season, higher product quality, early crop maturity, seedling production, better control of diseases and pests, conservation of raw materials and water, planting of selected varieties and considerable increase in production.

Despite the numerous advantages, greenhouses present poor thermal behavior since during the day elevated temperatures are observed and are difficultly avoided by natural ventilation, and at night temperatures often fall below the critical temperatures for the crops (Da Silva et al., 2000). For circumvent problems with high temperatures in greenhouses many producers use evaporative cooling systems, forcing air through a porous medium with a fan (pad-fan) or intermittent misting systems. These applications improve the thermal conditions and relative humidity during the hottest periods of the day.

Important aspects should be taken into consideration in the use of protected environments, such as knowing the different protection structures and their configurations and orientations, knowing the physiological responses of the crop to be cultivated within of the environment and knowing the energy and mass balance for the crop and its environment. This set of knowledge can aid in proper crop and environment management and obtain answers of the appropriate technology to be applied to the cropping system (Costa, 2004). The parameters of leaf growth, area and mass characterize the plant biomass, so that it can be used to determine changes in carbohydrate assimilation by the plant during a season of the year (Butler et al., 2002), where the leaf area measures the plant biomass accumulation potential and leaf dry mass allows for determination of the capacity of the plant to increase its dry weight through photosynthesis.

Microclimate environmental modifications of the greenhouse and screen, i. e., the plastic covers for vegetative production, has promoted a positive impact on crops, increasing fruit yield, leaf area and quality of products produced (Buriol et al. 1997, Segovia et al., 1997).

The microclimatic effects of the protected environment influence the emergence, initial growth and development of fruit trees, vegetables, ornamental plants and forests. The objective of this study was to perform a literature review of authors who have researched comparisons between different environmental conditions and their correlation with plant performance.

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