Luís Fernando Stone

Understanding how climate variability influences crop yield is essential for improving rice production, particularly in a country like Brazil with diverse agroclimatic zones. This study aimed to identify the key climatic drivers affecting lowland rice ( Oryza sativa L.) yields and to delineate optimal production areas using nonlinear modeling. We integrated 21,749 records from multiple‐environment trials conducted between 1982 and 2018 with large‐scale climate data spanning five Brazilian regions. To capture the nonlinear relationships between yield and environmental variables, generalized additive models (GAMs) were fitted separately for each region. As a novel contribution, we identified region‐specific climatic drivers, such as growing degree days, precipitation, temperature, humidity, and altitude, and applied the potential of mean increment (PMI) metric to pinpoint zones where yields are most likely to benefit from favorable climatic conditions. Results showed that temperature consistently influenced yield across all regions, though specific thresholds varied. For instances, in the South, high grain‐filling temperatures reduced yield, while in the North, higher minimum temperatures at flowering improved outcomes. Optimal areas were identified where both high PMI and observed yields coincided, offering spatially explicit targets for breeding and management. These findings highlight the utility of GAMs in capturing complex genotype–environment interactions and guiding climate‐smart agricultural practices. The approach informs regionalized strategies for crop calendar adjustment and ideotype development, enhancing climate resilience in rice production systems. By uncovering “environmental rules” for yield optimization, this framework contributes valuable insights for breeders, agronomists, and policymakers seeking sustainable intensification under climate uncertainty.

Addressing the intertwined challenges of food security and climate vulnerability requires robust and regionally tailored strategies for staple crops such as common beans. Although adjusting sowing dates is a key adaptive practice, spatio-temporal climate variability complicates the identification of optimal planting windows. This study integrates crop modeling with Functional Data Analysis (FDA) to quantify sowing-date-dependent yield losses for rainfed common beans across Central-Southern Brazil. The CSM-CROPGRO-Dry Bean model, driven by long-term climate data (1980–2016), soil properties, and management practices, was used to simulate yields for the BRS Estilo cultivar. FDA was subsequently applied to cluster yield-loss curves across municipalities and growing seasons, generating representative regional risk profiles. The results reveal clear spatial patterns. During the wet season, earlier sowing minimizes losses in Goiás, Minas Gerais, and western Paraná, whereas later sowing is beneficial in São Paulo, Santa Catarina, and eastern Paraná. In the dry season, earlier sowing consistently reduces losses across most regions. These patterns are primarily driven by water deficits and suboptimal temperatures during critical phenological phases. The resulting spatio-temporal sowing calendar provides an evidence-based decision-support tool to help farmers mitigate climatic risks. Moreover, it offers a scientific foundation for policymakers to refine sustainable management practices, improve crop insurance design, and enhance agricultural resilience and productivity under increasing climate uncertainty.

Chitosan-based biostimulants offer potential to improve crop performance under water deficit, yet their physiological modes of action in field-grown soybean remain poorly defined. Here, we evaluated FF-BR (patent number US 9,868,677 B2), a foliar formulation combining chitosan and pyroligneous acid, across two growing seasons and soybean cultivars under contrasting rainfall regimes in southern Brazil. In 2023/2024, treatments consisted of two FF-BR applications at an interval of 17 days at R1-R2 (beginning-full bloom) phase at doses of 0, 0.75, 1.0, and 1.25% (v/v). In 2024/2025, they were three and four applications of FF-BR at an interval of 18 days in the same phase. In 2023/2024, FF-BR applications in the mid-maturity cultivar Soytech ST 641 I2X increased linearly intrinsic water use efficiency (iWUE) through partial stomatal closure, maintaining carbon assimilation under terminal drought. These responses, likely mediated by abscisic acid (ABA) signaling and H₂O₂ accumulation, enhanced reproductive performance and increased yield by up to 481 kg ha⁻¹ (18.5% over control). In 2024/2025, early-maturing Neogen 610 was exposed to a moderate prolonged water deficit. Repeated FF-BR applications reduced carbon isotope discrimination (Δ¹³C), indicating sustained improvements in iWUE. Grain yield increased by 335 to 682 kg ha⁻¹ (7.3 to 15% over control), driven primarily by enhanced grain number. Heat map analysis of pod development revealed increased locule filling from node two upward, reflecting maintained assimilate allocation under stress. These results suggest that FF-BR application should target periods when stomatal regulation begins to limit carbon assimilation but precedes irreversible reproductive loss. This timing aligns with recent findings that priming, rather than boosting, is the core mechanism of effective biostimulants under abiotic stress. Overall, FF-BR represents a climate-adaptive, field-validated strategy to enhance drought resilience and stabilize soybean yields under irregular rainfall conditions.

A determinação do acúmulo de biomassa seca total da planta e de suas partes ao longo do ciclo pode ser utilizada para verificar o potencial produtivo de genótipos de feijoeiro. O objetivo do trabalho foi determinar a influência do acúmulo de biomassa da parte aérea na produtividade de cultivares de feijoeiro. Foram avaliadas, sob irrigação, sete cultivares, BRS FC414, BRS FC415, BRS FC423, BRS FC402, BRS FC416, BRSMG Amuleto e BRSMG Uai, no delineamento de blocos casualizados com quatro repetições, na safra de inverno de 2022, em Santo Antônio de Goiás, GO. Conduziu-se análise de crescimento ao longo do ciclo e quantificou-se a produtividade de grãos e o índice de colheita. As cultivares foram agrupadas em quadrantes, por meio de diagrama de dispersão, de acordo com a produtividade de grãos e a biomassa da parte aérea, e classificadas como mais ou menos produtivas. As cultivares mais produtivas acumularam maior biomassa na parte aérea e desenvolveram maior área foliar durante todo o ciclo do feijoeiro. Considerando-se a relação produtividade de grão e índice de colheita, as cultivares BRS FC416 e BRSMG Amuleto foram as mais eficientes na alocação de fotossintatos nos grãos e as cultivares BRS FC414 e BRSMG Uai foram as menos eficientes. Conclui-se que o acúmulo de biomassa da parte aérea e a manutenção de área foliar elevada ao longo do ciclo são fatores determinantes para maior produtividade de grãos e podem ser utilizados como critério auxiliar na seleção de cultivares de feijoeiro com maior potencial produtivo.

In Brazil, rice production is predominantly concentrated in the South region, employing a continuous flood irrigation system throughout the crop cycle. However, this irrigation management strategy in the tropical region contributes to low water‐use efficiency owing to adverse climatic conditions. Furthermore, with climate change projections indicating reduced water availability, the study aims to investigate the impact of alternative irrigation management strategies on the phenological development, gas exchange, biomass accumulation, and productivity of tropical irrigated rice. Three alternative irrigation management approaches—intermittent flood irrigation with aeration (IFA), intermittent flood irrigation throughout the growth cycle (IFC), and intermittent flooding up to the flowering stage (IFF)—were compared with the traditional continuous flood irrigation throughout the growth cycle. Phenological data, gas exchange, growth, and productivity dynamics were subject to analysis, providing overarching insights into management practices. Notably, irrigation management exhibited no influence on the vegetative phase of the crop. The implementation of intermittent flood irrigation facilitated a reduction in water supply without compromising the physiological performance of tropical irrigated rice. Strategies promoting judicious water utilization, such as IFA and IFC, can be readily integrated into the cultivation of tropical irrigated rice without detriment to grain yield or harvest index.

This study aimed to analyze the influence of climatic and geographic variables on the flowering process of flood-irrigated rice in the Midwest and North regions of Brazil. Agronomic data from the breeding program were related to the following variables: air temperature, relative humidity, global solar radiation, rainfall, degree days, latitude, longitude, and altitude. The analysis was performed using Multiple Linear Regression (MLR) and Generalized Additive (GAM) models. Cross-validation determined the most suitable model. The GAM model showed the best performance for both regions. In the Midwest and North of Brazil, flowering was strongly influenced by climate variables related to temperature. The rise in minimum temperatures tends to advance flowering. Higher minimum accumulated temperatures tend to delay flowering.