I first became interested (INRAE Colmar 1984-1987) in the below and above ground coordinated development of corn in relation with field conditions. Then, I related the capacity of a root to emit ramification with its vascularization (1986, Tokyo University, Japan) and cell organisation. In Avignon (1988 - today) my research has been focused on fruit trees (peach and apple) and more recently (2017 - onwards) on vine. I first showed that N (nitrogen) uptake by fruit trees (peach and apple) depended on current C (carbon) assimilation and transport toward the roots, meaning that the plants’ internal C reserves could not be considered as a simple buffer between plant intake and plant needs. That raised the question on how plants regulate the functional balance between their development (organ emergence and organisation within the plant structure), their growth (size increase of the existing organs), and their composition (organ concentration in defence and storage compounds namely). For perennial plants, growing conditions and life background affect each of these aspects differently, with possible antagonistic effects on plant condition. Plant susceptibility to biotic and abiotic stresses is thus determined by developmental and trophic aspects, which could be manipulated by cultural practices, such as irrigation and fertilisation. This is the topic of my current research, focused on peach and vine dieback on one hand, and on peach and apple susceptibility to aphids, on the other hand. My final aim is to redefine the culture conditions so as to limit the water, N and pesticides inputs, but maintain plant health, productivity and longevity.

Seminal publications:

Jordan M.O. Hucbourg B. Drevet A. (2021) How to shift from research to commercial orchards? A case study on aphid-peach tree interactions as affected by nitrogen and water supplies. Insects: Special Issue "Biology and management of sap sucking insects" 12(11), 1003. DOI 10.3390/insects12111003

Jordan M.O. (2015). C depletion and tree dieback in young peach trees: a possible consequence of N shortage? Annals of Forest Science, 72 (5), 529-537. DOI: 10.1007/s13595-015-0466-9

Jordan M. O. Vercambre G. Gomez L. Pagès L. (2014) The early spring N uptake of young peach trees (Prunus persica) is affected by past and current fertilizations and levels of C and N stores. Tree Physiology (Oxford Academic), 34 (1), 61-72. DOI: 10.1093/treephys/tpt109

Jordan MO, Wendler R. Millard P. (2009) The effect of autumn N supply on the architecture on young peach (Prunus persica L.). Trees 23: 235-245. DOI 10.1007/s00468-008-0271-2

Jordan M.O. Habib R. (1996) Mobilizable carbon reserves in young peach trees as evidenced by trunk girdling experiments. Journal of Experimental Botany, 47 (294), 79-87. DOI: 10.1093/jxb/47.1.79

Jordan M.O. Harada J. Bruchou C. Yamazaki K. (1993) Maize nodal root ramification: absence of dormant primordia, root classification using histological parameters and consequences on sap conduction. Plant and Soil 153, 125-143. DOI: 10.1007/BF00010551

Pagès L. Jordan M.O. Picard D. (1989) A simulation model of the three-dimensional architecture of the maize root system. Plant and Soil 119, 147-154. DOI:10.1007/BF02370279

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