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Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean region. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd.) tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed). The chlorophyll a fluorescence transients were analyzed by the JIP-test to translate stressinduced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (φP0 = Fv/Fm), and the quantum yield of electron transport (φE0). The amount of active Photosystem II (PSII) reaction centers (RC) per excited cross section (RC/CS) also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC) increased and the effective dissipation per active reaction centers (DIo/RC) increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI), was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.

Given the current water shortage in North Africa, improving water management to produce more crop per drop is vital. In addition, the introduction of drought-tolerant, less water-consuming crops such as quinoa is of great interest. To understand the response of quinoa to water stress in terms of biomass and grain yield under various irrigation management strategies, the SALTMED model was employed using field measurements during the cropping seasons of 2011 and 2012 at a site in the Marrakech region, south Morocco. Quinoa showed its ability to grow in the south of Morocco and give a good yield under full irrigation. However, the experimental and modelling results showed that under rainfed and deficit irrigation, the grain yield was lower than under the full irrigation treatment and was dependent on water deficit level. The study revealed that a reasonable grain yield of quinoa can only be obtained if it was subjected to moderate water stress conditions. The results indicated that the SALTMED model is able to simulate the quinoa biomass and grain yield under various water deficit levels and that the model can be used in the evaluation of different irrigation strategies. Copyright © 2015 John Wiley & Sons, Ltd. RÉSUMÉVu le déficit hydrique que connait l'Afrique du Nord, l'amélioration de la gestion de l'eau pour augmenter l'efficience de son utilisation est devenue vitale pour l'agriculture. En plus l'introduction de cultures tolérantes au déficit hydrique et moins consommatrices d'eau est d'un grand intérêt pour la région. Pour comprendre la réponse du quinoa aux différents niveaux de stress hydrique en ce qui concerne le rendement en grains et la biomasse, le logiciel de modélisation SALTMED a été utilisé en y introduisant les valeurs des mesures prises au champ, durant les deux compagnes agricoles 2011 et 2012, dans un site dans la région de Marrakech au sud du Maroc. Le quinoa a montré une grande aptitude à croitre et à donner de bons rendements sous le traitement 100% ETc. Cependant, les résultats expérimentaux et ceux de SALTMED montrent que les rendements en grains sous régime non irrigué et sous déficit hydrique sont inférieurs à celui obtenu sous 100% ETc, et qu'ils sont proportionnels à l'intensité du déficit hydrique. L'étude a révélé que l'on peut obtenir un rendement raisonnable sous déficit hydrique modéré. Les résultats ont montré que le logiciel de modélisation SALTMED est capable de simuler le rendement en grain et biomasse sous différents niveaux de déficit hydrique, et que celui-ci peut être utilisé pour l'évaluation de différentes stratégies d'irrigations.

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