Eric Jallas

Leaf orientation and sunlit leaf area distribution in cotton

The diurnal leaf orientation behaviour of row-planted cotton plants (Gossypium hirsutum L. cv. ‘DES 119’) and its relationship to sunlit leaf area distribution at three stages of development were studied in the field. Electromagnetic digitizing was used for plant geometrical structure measurement for three periods of 2 h during the day. Cotton leaves showed a diaheliotropic response throughout the day. This heliotropic behaviour varied according to growth stage. In addition to changes in orientation, leaves also moved in space. The distance moved by a leaf between two observation times increased with stage of development, in agreement with petiole and blade lengths. Sunlit leaf area distribution varied according to stage of development. Analysis of interception showed that probability of light interception was greater in the morning and in the afternoon than at noon. Without a diurnal change in canopy structure, cotton plants would intercept less direct radiation in the morning and in the afternoon. Leaf dispersion was regular during the first and last stage of development, but it was clumped during the intermediate stage. Leaf dispersion was more regular in the morning and the afternoon than at noon.. Leaf dispersion, however, changed primarily with sun direction and not with canopy structure. This would indicate that small changes in leaf location do not significantly affect light interception. Finally, the ecological significance of diaheliotropism and the implications for modelling light interception in cotton plants are discussed.

Modeling: A Central Activity for Flexible Information Systems Development in Agriculture and Environment

Enterprise information systems in agriculture and environment are becoming more complex and difficult to design and implement. This paper aims to show our vision on using model-based approaches to design complex and flexible agricultural and environmental information systems. At the center of this modeling approach is the Unified Modeling Language that facilitates expressing visually concepts of a problem domain and their relationships. UML has a core of notations that are generic and that can be used to model problems in any domain but can be extended to create profiles in order to take into consideration modeling concerns in a particular problem domain. UML profiles are created to use UML in designing spatial systems, ontologies, model driven architecture-based systems and Web-based systems and a recent profile makes it possible to use UML for business modeling purposes. UML is used to present design patterns; their use is crucial in designing complex and flexible information systems. Recently, UML is enriched with Object Constraint Language that is used to express constraints on modeling artifacts. The paper presents the state of the art in modeling agricultural and environmental systems and provides discussions for future directions.

The Model Driven Architecture Approach: A Framework for Developing Complex Agricultural Systems

Development and application of crop models is increasingly constrained by the difficulty of implementing scientific information into an efficient simulation environment. Traditionally, researchers wrote their own models and tools, but as software has become much more complex, few researchers have the means to continue using this approach. New modeling paradigms provided by the software engineering industry can be successfully used to facilitate the process of software development for crop simulation systems.

Design of a Model-Driven Web Decision Support System in Agriculture: From Scientific Models to the Final Software

This chapter aims at introducing a new type of design of decision support systems (DSSs). The DSS presented here is a software based on client–server technology that enables great accessibility by the Web. Its conception flow has been established to be generic and not explicitly problem-oriented. In this way, once the first DSS is built, the creation of other DSSs will be easy and time-saving. The creation of the DSS requires the collaboration of different experts such as agronomists, computer specialists, and interface experts. Their communication is improved by the use of the formal language Unified Modeling Language (UML) throughout the process of software design. The relevance of the DSS comes from its use of scientific mechanistic models adapted to the users’ needs and from a flexible architecture that allows easy software maintenance. The chapter is structured as follows: after the introduction, the second section will explain in detail the methods used to build the scientific models that describe the biological system. The third section describes the methods for the validation and implementation of those models, and the fourth section deals with the transcription of the models into software components processable in the DSS. Finally, the last section of this chapter describes the architecture of the client–server application.

Precision Farming, Myth or Reality: Selected Case Studies from Mississippi Cotton Fields

There is a lot of interest in the concept of precision farming, also called precision agriculture or site-specific management. Although the total acreage managed by these concepts is increasing worldwide each year, there are several limitations and constraints that must be resolved to sustain this increase. These include (1) collecting and managing the large amounts of information necessary to accomplish this micromanagement, (2) building and delivering geo-referenced fine-scale (i.e., change every few meters or less) prescriptions in a timely manner, (3) finding or developing agricultural machines capable of quickly and simultaneously altering the rates of one or more agri-chemicals applied to the crop according to a geo-referenced prescription, (4) the need to have personnel stay “current” with advancements in developing technologies and adapting them to agriculture, (5) refining existing and/or creating new analytical theories useful in agriculture within a multidisciplinary, multi-institutional, and multibusiness environment of cooperation, and (6) modification of agricultural practices that enhances environmental conservation and/or stewardship while complying with governmental regulations and facing difficult economic constraints to remain profitable. There are many myths that overshadow the realities and obscure the true possibilities of precision agriculture. Considerations to establish productive linkages between the diverse sources of information and equipment necessary to apply site-specific practices and geographically monitor yield are daunting. It is anticipated that simulation models and other decision support systems will play key roles in integrating tasks involved with precision agriculture. Discovering how to connect models or other software systems to the hardware technologies of precision agriculture, while demonstrating their reliability and managing the flows of information among components, is a major challenge. The close cooperation of the extension, industrial, production, and research sectors of agriculture will be required to resolve this constraint.

A model-driven decision support system for vineyard water status management: a time-dependent sensitivity analysis

The global sensitivity analysis of a dynamic soil water balance model embedded in a Decision Support System for vineyard water management is achieved via the Sobol variance-based method. The sensitivity analysis is applied sequentially at each simulation step so that the variation of parameter influence over time can be followed. Results allow identification of four soil-related parameters having the highest influence at the vine plot scale, and for various climate scenarios. This provides fundamental information for the operational use of the model, i.e. when few input data are available to the end-user.