Organic plant breeding: a challenge for practice and science

This paper gives a short overview of the current practical and scientific challenges of plant breeding programmes for organic agriculture in Europe. Research is challenged to prove that organic plant breeding is more than just conventional plant breeding for another market, and to develop appro-priate concepts and strategies for improving varieties adapted to the principles and needs of organic farm-ing systems. Emphasis is on defining crop ideotypes and selection criteria, and on developing selection strategies, and on socio-economic and legal obstacles

Using numerical plant models and phenotypic correlation space to design achievable ideotypes

Numerical plant models can predict the outcome of plant traits modifications resulting from genetic variations, on plant performance, by simulating physiological processes and their interaction with the environment. Optimization methods complement those models to design ideotypes, i.e. ideal values of a set of plant traits resulting in optimal adaptation for given combinations of environment and management, mainly through the maximization of a performance criteria (e.g. yield, light interception). As use of simulation models gains momentum in plant breeding, numerical experiments must be carefully engineered to provide accurate and attainable results, rooting them in biological reality. Here, we propose a multi-objective optimization formulation that includes a metric of performance, returned by the numerical model, and a metric of feasibility, accounting for correlations between traits based on field observations. We applied this approach to two contrasting models: a process-based crop model of sunflower and a functional-structural plant model of apple trees. In both cases, the method successfully characterized key plant traits and identified a continuum of optimal solutions, ranging from the most feasible to the most efficient. The present study thus provides successful proof of concept for this enhanced modeling approach, which identified paths for desirable trait modification, including direction and intensity.Comment: 25 pages, 5 figures, 2017, Plant, Cell and Environmen

Towards a Law of Invariance in Human Concept Learning

Invariance principles underlie many key theories in modern science. They provide the explanatory and predictive framework necessary for the rigorous study of natural phenomena ranging from the structure of crystals, to magnetism, to relativistic mechanics. Vigo (2008, 2009)introduced a new general notion and principle of invariance from which two parameter-free (ratio and exponential) models were derived to account for human conceptual behavior. Here we introduce a new parameterized \ud exponential “law” based on the same invariance principle. The law accurately predicts the subjective degree of difficulty that humans experience when learning different types of concepts. In addition, it precisely fits the data from a large-scale experiment which examined a total of 84 category structures across 10 category families (R-Squared =.97, p < .0001; r= .98, p < .0001). Moreover, it overcomes seven key challenges that had, hitherto, been grave obstacles for theories of concept learning

The GIST of Concepts

A unified general theory of human concept learning based on the idea that humans detect invariance patterns in categorical stimuli as a necessary precursor to concept formation is proposed and tested. In GIST (generalized invariance structure theory) invariants are detected via a perturbation mechanism of dimension suppression referred to as dimensional binding. Structural information acquired by this process is stored as a compound memory trace termed an ideotype. Ideotypes inform the subsystems that are responsible for learnability judgments, rule formation, and other types of concept representations. We show that GIST is more general (e.g., it works on continuous, semi-continuous, and binary stimuli) and makes much more accurate predictions than the leading models of concept learning difficulty,such as those based on a complexity reduction principle (e.g., number of mental models,structural invariance, algebraic complexity, and minimal description length) and those based on selective attention and similarity (GCM, ALCOVE, and SUSTAIN). GIST unifies these two key aspects of concept learning and categorization. Empirical evidence from three\ud experiments corroborates the predictions made by the theory and its core model which we propose as a candidate law of human conceptual behavior

Participatory Plant Breeding Methods for Organic Cereals

Formal breeding methods were not always suitable to address the very large diversity of both environmental conditions and end-user needs. Both were frequently encountered either in marginal areas of developing countries or in organic farms of EEC. Participatory plant breeding (PPB) methods represent alternatives aimed to improve local adaptation breeding, to promote genetic diversity, to empower farmers and rural communities. The term PPB refers to a set of breeding methods usually distinguished by the objectives (functional or process approach), institutional context (farmer-led or formal-led), forms of interaction between farmers and breeders (consultative, collaborative or collegial), location of breeding (centralized or decentralized), stage of farmers participation in the breeding scheme (participatory varietal selection or participatory plant breeding)… Among all these methods, the best strategies for organic breeding and their impacts on breeding techniques are discussed. A PPB program actually conducted at INRA – Montpellier (F), involves the whole organic durum wheat interprofessional organization, from farmers to consumers. It is used to assess the interest of a multidisciplinary approach and to discuss the role of each participant in such program. Must participation be seen as a means towards an end or an end in itself

WECOF: A new project developing enhanced weed control through improved crop and plant architecture

A primary objective of the EU-funded WECOF project is to optimise the natural competitiveness of winter wheat in reducing weed growth, and thus reduce the need for direct weed control interventions. Crops are characterised by ranking the relative importance of key plant and crop factors in shading weed growth. A series of core trials have been established in Germany, Scotland, Poland and Spain comparing plant structure by the use of different varieties and crop architectural factors by the use of different sowing row widths and direction. Variety trials have also been established in Scotland with constant row width and sowing direction to give more detailed varietal comparisons. Results from the first set of trials in Scotland are described. There are clear varietal differences in weed suppression; row-width has a bigger effect than sowing direction. Results will be used to develop models to assist breeders in producing improved crop ideotypes for organic production, and in production of a decision support system to assist farmers and advisers in variety selection and management for improved weed suppression. WECOF also includes work on allelopathy and photocontrol, and on the related economic factors

The Critical Point of Conventionally Bred Soft Wheat Varieties in Organic Farming Systems

Nowdays, wheat is the most important crop for organic farming system. However, the varieties breeded and tested in the conditions of organic farming system are still missing. It gives rise to very low level of yield in the Czech Republic (less than 50% of level of convention one in the same conditions). One of the reasons is that the ideotype of organic breeded variety is different from conventional one. The varieties suitable for organic farming system differ in many respects from those adopted in conventional farming. The first difference is obvious from the conventional tests of use value of the varieties, taking just some direct indicators influencing the main parameter (yield) into account. Generally speaking, the features to be tested can be divided into 4 groups: the morphological, the biological, the economic and quality parameters. The conventional varieties are bred in conditions characterised by an abundance of soluble nutrients, and therefore, their root systems are not adapted to an insufficiency of nutrients or weaker bonding of nutrients. The competitiveness to weeds has also been ignored. Any conventional variety, which has never confronted any strong weeds during the breeding process, cannot be assumed to be competitive enough in the conditions of an organic agroecosystem. Resistance to diseases and pests can be similarly characterised. The variety is protected by pesticides throughout the conventional breeding process. Because of the seasonal fluctuations in weather, we need a plastic and flexible variety. They are also different from the point of view of their qualitative parameters