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A domestication assessment of the big five plant families

Hammer, Karl, Khoshbakht, Korous
Genetic resources and crop evolution 2015 v.62 no.5 pp. 665-689
Asteraceae, Fabaceae, Orchidaceae, Poaceae, Rhizobium, Rubiaceae, adverse effects, air, bacteria, coevolution, domestication, geographical distribution, horticultural crops, nitrogen, oils, ornamental plants, rodents, seed quality, species diversity, starch, storage quality
To assess domestication levels in the five big families of higher plants (Compositae, Leguminosae, Orchidaceae, Rubiaceae, Gramineae) we propose an index that categorizes taxa according to the strength of domestication. The selection of species followed the Mansfeld approach, i.e. all plants cultivated by man with the exception of ornamentals have been included. The basis for our studies was Mansfeld’s Encyclopedia (Hanelt and IPK in Mansfeld’s encyclopedia of agricultural and horticultural crops, vol 1. Springer, Berlin, p 6, 2001). Information about additional cultivated species has been collected in the past years. Altogether 2,166 cultivated species have been analyzed—1.013 Leguminosae (5.2 %), 735 Gramineae (7.6 %), 293 Compositae (1.2 %), 84 Rubiaceae (0.7 %) and 41 Orchidaceae (0.2 %) (in brackets the percentages of cultivated species within the respective families). The domestication assessment confirmed the importance for man of the families with relative high numbers of highly domesticated (H), domesticated (D) and semi-domesticated (S) species for Gramineae and Leguminosae, followed by Compositae, and relative low levels for Rubiaceae and Orchidaceae. The assessment data of Compositae, Leguminosae and Gramineae are mainly shown for H (because of the great number of species), for Rubiaceae and Orchidaceae they are provided in total, including all assessment categories. Selected species from the different families are discussed within their commodity groups. The reasons for the differences between the families are analyzed. Factors causing high levels of domestication assessment are high species diversity, global geographic distribution, good seed storability, good seed quality characters (starch and oil) and the earlier co-evolution of plants and animals (rodents) towards seed/fruit sizes and qualities. Leguminosae can make use of the nitrogen from the air with the help of Rhizobium bacteria. Gramineae can effectively use the available nitrogen. This has led to combined suitabilities for domestication and agricultural developments. The paucity of domesticated species is dependent on high specialisation, a high level of secondary defense compounds and the lack of carbohydrates digestible for man. Diverse cultural and genetic factors can have positive or negative effects on use preferences by man.