Une expérience réalisée à Coruche (Portugal) sur une culture de tomate a permis de tester plusieurs critères de contrainte hydrique relatifs à la plante et à son microclimat. Le potentiel hydrique de base et la conductance stomatique sont des critères très sensibles à un arrêt de l'irrigation. Les critères microclimatiques (température et flux de surface) peuvent être intéressants, si certaines précautions relatives à la dimension de la parcelle étudiée sont prises. Le critère le plus sensible et le plus simple à déterminer est cependant le potentiel de base. On suggère par conséquent, de l'utiliser pour diagnostiquer les périodes de contrainte hydrique chez les plantes cultivées dans des conditions expérimentales voisines de celles étudiées ici.Mots clés additionnels : Potentiel hydrique foliaire, température radiative, résistance stomatique, rapport du flux de chaleur sensible au rayonnement net, tomate, irrigation. SUMMARY A study of several indicators of the water status of a tomato crop in a semi-arid region.An experiment conducted on a tomato crop at Coruche (Portugal) enabled the authors to test several water stress indicators for the plant and its microclimate. Predawn leaf water potential and stomatal conductance were very sensitive indicators of water stress. Microclimatic criteria (crop radiative temperature and parameters referring to fluxes above the canopy) could be useful provided certain precautions on the dimensions of the plot are taken. The most sensitive and easily determined of the indicators was, however, predawn leaf water potential. We therefore suggest its use as an appropriate diagnostic measure for water stress in cultivated plants grown under experimental conditions close to those studied here.Additional key words : Leaf water potential, radiative temperature, stomatal conductance, ratio of'sensible heat to net radiation, tomato crop, irrigation.

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The fluctuations in yield and consequently in production occurred due to climatic adversities in the main producing states of Brazil. Farming has changed over time, and past scenarios have shown high exploitation of natural resources focusing on soil tillage and conventional seeding methods. This study aimed to determine the yield performance of soybean grown under 10 consolidated crop succession systems. The experiment was conducted during the 2018/2019 crop season, before the research project entitled “Sustainable production systems with better use of biological and natural resources, with treatments arranged in a randomized block design and four replications”. The treatments consisted of the following predecessor crops: Avena sativa, Avena strigosa, Triticum aestivum, Secale cereale, Brassica napus, Raphanus sativus, Avena strigosa + Raphanus sativus + Vicia sativa, Fallow, Avena strigosa + Lolium multiflorum, and Triticum aestivum – Fodder. Soybean was subsequently sown across winter crops. The succession that showed superior yield was Avena strigosa + Lolium multiflorum. This attribute was established by associating taller plants with the maximization of the number of grains per pod, hundred-grain mass, grain mass, and plant dry mass; in contrast, there was a lower emphasis on plant residue. The determining attributes for soybean yield were plant stand, plant height, the number of pods per plant, and total grain mass, with contrasts among groups composed of the succession of Avena sativa, Avena strigosa, Triticum aestivum, Secale cereale, and Brassica napus, distanced from Raphanus sativus, Avena strigosa + Raphanus sativus + Vicia sativa, Fallow, Avena strigosa + Lolium multiflorum, and Triticum aestivum - Fodder.