Organic and low-input agriculture needs flexible varieties that can buffer environmental stress and adapt to the needs of farmers. We implemented an experiment to investigate the evolutionary capacities of a sample of spinach (Spinacia oleracea L.) population varieties for a number of phenotypic traits. Three farmers cultivated, selected and multiplied one or several populations over two years on their farms. The third year, the versions of the varieties cultivated and selected by the different farmers were compared to the original seed lots they had been given. After two cycles of cultivation and on-farm mass selection, all the observed varieties showed significant phenotypic changes (differences between the original version and the version cultivated by farmers) for morphological and phenological traits. When the divergence among versions within varieties was studied, the results show that the varieties conserved their identity, except for one variety, which evolved in such a way that it may now be considered two different varieties. The heterogeneity of the population varieties was assessed in comparison with a commercial F1 hybrid used as control, and we found no specific differences in phenotypic diversity between the hybrid and population varieties. The phenotypic changes shown by the population varieties in response to on-farm cultivation and selection could be useful for the development of specific adaptation. These results call into question the current European seed legislation and the requirements of phenotypic stability for conservation varieties.

Organic agriculture is enhancing specific plant breeding activities to meet its requirements for varieties better adapted to the specific organic environment. In the past five years, therefore, attempts have been made to translate the principles of organic farming into rules, regulations and guidelines for organic plant breeding and propagation. These principles are based on the concept of naturalness, which includes three complementary approaches: the non-chemical approach, the agro-ecological approach and the integrity approach. Departing from the concept of naturalness, criteria have been developed to evaluate existing plant breeding and propagation techniques for their compliance to the principles of organic agriculture. Each of the three approaches of the concept of naturalness has major consequences. If these consequences are taken seriously, plant breeding and propagation strategies and techniques for organic farming will greatly differ from breeding and propagation for conventional farming. To better understand the choices to be made and to make them acceptable to the mainstream seed industry, it is necessary to further clarify the underlying framework. This paper provides this clarification by analysing the cognitive, emotive, and normative dimensions of the three approaches. Distinguishing the three different approaches of naturalness in organic agriculture, as well as their three dimensions, and analysing the consequences for the breeding and propagation strategies and techniques can also help to identify and prioritize short-term and long-term steps for the practical development of organic seed production and plant breeding.