Summary Water scarcity due to global warming can increase the water demand for upland rice at critical stages of crop development. However, there is little research on cultivar responses to this scenario and technologies that enhance water use efficiency (WUE). To determine the influence of water stress at and after flowering stages of drip-irrigated upland rice cultivars on physiology, yield, and WUE, a shelter experiment was conducted using a randomized block design with a split-plot arrangement of treatments. Three modern and one traditional cultivar were subjected to five irrigation managements: 100% of the field capacity considered the reference management (RM), 70 and 40% of the RM at the flowering stage, and 70 and 40% of the RM at the grain-filling stage. In general, the modern cultivars tended to maintain higher photosynthetic rate, stomatal conductance, transpiration, leaf water potential, and lower crop water stress index compared to the traditional cultivar under water stress. The WUE decreased for all cultivars under severe stress, averaging 0.55 and 0.62 kg m−3 when stress occurred at flowering and grain-filling, respectively, whereas moderate stress imposed at grain-filling maintained WUE for all cultivars, averaging 1.21 kg m−3. In addition, grain yield (GY) showed a similar variation trend under drought stress as WUE, and its reduction was mainly associated with low filled grain percentage. Among the five irrigation treatments, both GY and WUE were the highest in the RM; the best cultivar recorded 9.3 Mg ha−1 and 1.62 kg m−3, respectively. Findings suggest that attending to the full water demand under precision drip irrigation and appropriate cultivar selection can enhance upland rice production at significant levels.

In recent decades, research on precision irrigation driven by climate change has developed a multitude of strategies, methods and technologies to reduce water consumption in irrigation projects and to adapt to the increasing occurrence of water scarcity, agricultural droughts and competition between agricultural and industrial sectors for the use of water. In this context, the adoption of water-saving and application practices implies a multidisciplinary approach to accurately quantify the water needs of crops under different water availability and management practices. Thus, this review article presented a review of technologies and new trends in the context of precision irrigation, future perspectives and critically analyze notions and means to maintain high levels of land and water productivity, which minimize irrational water consumption at the field level.

Produtividade da área e da água em soja irrigada para diferentes variedades e metodologias de manejo da irrigação / Ana Carolina Ferreira França. --versão revisada de acordo com a Resolução CoPGr 6018 de 2011. --Piracicaba, 2023. 73 p.Dissertação (Mestrado) --USP / Escola Superior de Agricultura "Luiz de Queiroz".1. Produtividade da água 2. Glycine max 3. Agricultura irrigada 4. Eficiência do uso da água L. . I. Título AGRADECIMENTOSÁ Deus, por me abençoar, proteger e permitir chegar até aqui.Aos meus pais, por todo suporte e amor, que sem os quais eu jamais teria finalizado mais essa etapa. Essa conquista é nossa! À minha irmã e toda a minha família, pelo apoio e carinho durante essa jornada.Aos meus amigos, de longa data e recentes, pelos momentos de verdadeira amizade, alegria e respeito, que tornaram meus dias mais leves.Aos meus colegas de departamento e amigos, em especial Alice, Michele, Sarah, Carlos, Júnior e Hugo, por todo apoio e momentos especiais ao longo dessa jornada.Ao meu orientador, Prof. Dr. Rubens Duarte Coelho, pela oportunidade, acolhimento, paciência e conhecimento para a conclusão desta etapa.

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