Abstract
ABSTRACT Sorghum is of significant economic importance for Northeastern Brazil, since it exhibits high growth rates in regions with irregular rainfall distribution and high temperatures, and is an alternative to corn, which has greater water requirements. Despite being a traditional crop in the region, there are few studies on irrigation management in the Apodi plateau. The aim of this study was to determine the evapotranspiration of the crop and the crop coefficient (Kc) for the different stages of sorghum growth in two cycles, and establish the relationship between the Kc and the normalized difference vegetation index (NDVI) obtained by radiometry. Two weighing lysimeters were used to estimate crop evapotranspiration (ETc). Reference evapotranspiration (ETo) was estimated by the Penman-Monteith method (FAO) and the crop coefficient determined using two methodologies: simple Kc and dual Kc. Total crop evapotranspiration in the two cycles was 452 and 557 mm. The ETc value was 23% higher in the second cycle compared to the first. The maximum Kc values for the first and second cycles were 1.21 and 1.35, respectively, using the dual Kc methodology. The linear relationship found between the Kc values and the NDVI allows monitoring and estimating the water requirements of the crop.
Highlights
Sorghum (Sorghum bicolor (L.) Moench) is grown for its climate resilience and versatility in the production of grains and forage for animal feed, as well as the production of bioenergy in different regions of the world
The aims of this study were to determine the water requirements of irrigated sorghum using a weighing lysimeter, and its respective simple and dual Kc for the soil and climatic conditions of the Apodi Plateau in order to establish the relation between Kc and the normalized difference vegetation index (NDVI) obtained by radiometry
High water requirement was observed for the sorghum crop, totaling 452 and 557 mm in the first and second cycles, respectively
Summary
Sorghum (Sorghum bicolor (L.) Moench) is grown for its climate resilience and versatility in the production of grains and forage for animal feed, as well as the production of bioenergy in different regions of the world. Sorghum is considered the fifth most produced cereal in the world, after wheat, rice, corn and barley (FAOSTAT, 2018). The total planted area of sorghum was 42 million hectares in 2018, producing 59 million metric tons of grain (FAOSTAT, 2018). According to Dias & Blanco (2010), sorghum is the most indicated cereal in the semiarid of Northeastern Brazil since it adapts well to the abiotic stresses in this region. Sorghum is grown by producers in Rio Grande do Norte state, Brazil, during the rainy season and under irrigation in the dry period. Despite being a traditional crop in the region, there are few studies on irrigation management in the Apodi Plateau
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