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Climate change greatly influences coffee production, especially in areas infested with plant‐parasitic nematodes. In this study, coffee genotypes showed differences in their morphological and physiological characteristics when subjected to a water deficit and parasitism by Meloidogyne paranaensis. The cultivar IPR 100 had the largest superficial and volumetric root system area, even when parasitized. The two progenies (MG 0179‐1 and MG 0179‐3) and the cultivar Catuaí IAC 62 had a similar surface area (p < .05) when parasitized. However, the root surface area and volume of MG 0179‐3 increased by 96% and 400%, respectively, when parasitized by M. paranaensis. On the other hand, Catuaí IAC 62 had a 31% reduction in root surface area. Catuai 62 and IPR 100 showed higher sensitivity to drought when parasitized because of the increased photochemical sensitivity and reduction in photochemical quenching. In MG 0179‐1 and MG 0179‐3, an increase in non‐photochemical quenching occurred in response to stress, indicating that these progenies use a photochemical response to protect photosystem II. In this work, MG 0179‐3, which is resistant to M. paranaensis, was remarkable because, interestingly, the infestation caused an increase in its root surface area. In addition, MG 0179‐3 had relatively good photochemical performance under water deficit and M. paranaensis parasitism.

Traditionally, water conditions of coffee areas are monitored by measuring the leaf water potential (Ψ W) throughout a pressure pump. However, there is a demand for the development of technologies that can estimate large areas or regions. In this context, the objective of this study was to estimate the Ψ W by surface reflectance values and vegetation indices obtained from the Landsat-8/OLI sensor in Minas Gerais-Brazil Several algorithms using OLI bands and vegetation indexes were evaluated and from the correlation analysis, a quadratic algorithm that uses the Normalized Difference Vegetation Index (NDVI) performed better, with a correlation coefficient (R 2) of 0.82. Leave-One-Out Cross-Validation (LOOCV) was performed to validate the models and the best results were for NDVI quadratic algorithm, presenting a Mean Absolute Percentage Error (MAPE) of 27.09% and an R 2 of 0.85. Subsequently, the NDVI quadratic algorithm was applied to Landsat-8 images, aiming to spatialize the Ψ W estimated in a representative area of regional coffee planting between September 2014 to July 2015. From the proposed algorithm, it was possible to estimate Ψ W from Landsat-8/OLI imagery, contributing to drought monitoring in the coffee area leading to cost reduction to the producers.

The aim of the present study was to find out the effect of calcium on flooded maize seedlings by anatomical and ultra‐structural analyses and by measuring the enzyme activity and gene expression of polygalacturonase (PG) and superoxide dismutase (SOD). For this, maize seeds were placed to germinate in germination paper saturated with CaCl2 0.75 %. Then, 4‐day‐old seedlings were subjected to flooding in the presence or absence of CaCl2. Mesocotyl sections were sampled daily for the anatomical and ultra‐structural analyses, RT‐qPCR and activity of SOD and PG. The results showed that the presence of calcium in the flooding buffer increases the tolerance of maize seedlings by 1 day when compared to seedlings flooded in the absence of this element. The reason for this longer survival is that calcium maintains the integrity of the cell wall and attenuates the effects of oxidative stress. Owing to this fact, the seedlings remained alive and firm for up to 7 days.

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