The estimate of the actual surface evapotranspiration (ET) contributes to quantifying the water needs of crops. An alternative to the use of lysimeter for an accurate estimation of water needs, which has proved to be of great value in recent years, is the use of remote sensing combined with models based on surface energy balance. There is wide variety of models that can be classified into two types: one-source models, such as the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) algorithm, or two-source models, such as the Simplified Two-Source Energy Balance (STSEB). The objective of this study was to analyze how METRIC and STSEB can be used to estimate ET, in comparison with the lysimeter data, for the different stages of development of the sorghum crop in Apodi, RN, Brazil. The accuracy of both models in the daily ET estimation for the semi-arid conditions of the experiment, with RMSE values of 0.8 and of 0.7 mm d-1 through METRIC and STSEB, respectively, is considered acceptable for irrigation management purposes. The errors obtained with METRIC at an instantaneous scale were 60, 50, 130 and 5 W m-2 for Rn, LE, H and G, respectively, on the other hand, using STSEB these errors were of 40, 70, 120 and 21 W m-2 for Rn, LE, H and G, respectively. The METRIC and STSEB models are very similar when it comes to providing information on water needs of the sorghum.

Nutritional management can be an efficient strategy to mitigate the effects of salinity on fruit production and quality. This study aimed to evaluate the production and quality of fruits of mini watermelon crop, Sugar Baby cultivar, grown in a protected environment, under salt stress and K+/Ca2+ ratios. The study was carried out in a greenhouse, using a randomized block design, 1 + 5 scheme, resulting in six treatments and four replications. Six nutrient solutions were employed, one using low-salinity water, with NaCl (0.5 dS m-1) and standard nutrient solution (S1, control treatment), and the others using salinized water at 5.0 dS m-1 (S2) and extra addition of K (S3 = 50% and S4 = 100%) and Ca (S5 = 50% and S6 = 100%). The production (fruit production, longitudinal and transverse diameter of fruit, rind thickness, pulp firmness) and postharvest quality (soluble solids, vitamin C, titratable acidity, and maturation index), in addition to the variables related to the color of the pulp (lightness, chroma index, and Hue angle) were evaluated. The addition of NaCl reduced fruit production, longitudinal, and transverse diameter of fruit, rind thickness, and vitamin C content. Among saline nutrient solutions, extra addition of 50% K (S3) attenuates the deleterious effects of salt stress on the production variables and vitamin C content. Under salt stress, extra addition of 50% K (S3) and 100% Ca (S6) intensifies the red color of the pulp.

RESUMO: Objetivou-se avaliar o desempenho de cultivares de manjericão fertigadas com soluções nutritivas salinizadas em cultivo semi-hidropônico. O experimento foi conduzido em casa de vegetação, seguindo o delineamento experimental de blocos casualizados, em esquema fatorial 5 x 3, sendo cinco cultivares de manjericão (Grecco a Palla, Alfavaca Basilicão, Alfavaca Verde, Lemoncino e Roxo) e três salinidades da solução nutritiva (2,0; 3,5 e 5,0 dS m-1), com três repetições, sendo a parcela experimental representada por três vasos contendo 3,0 dm3 de fibra de coco e uma planta em cada. Aos 60 dias após o transplantio as plantas foram avaliadas quanto à altura de plantas, número de folhas, número de hastes e de inflorescência, comprimento de inflorescências, diâmetro do caule, massa seca (folhas, hastes, inflorescências e total), área foliar, área foliar especifica, razão de área foliar, suculência foliar e o índice de tolerância a salinidade. De forma geral, houveram diferentes respostas entre as cultivares com relação a salinidade. A fertirrigação usando água de alta salinidade promove alterações no crescimento das cultivares sensíveis de manjericão. As cultivares Alfavaca Basilicão, Alfavaca Verde e Roxo foram tolerantes a todos níveis salinos testados (2,0; 3,5 e 5,0 dS m-1), enquanto as cultivares Grecco a Palla e Lemoncino foram tolerantes até a salinidade de 3,5 dS m-1.