Stress conditions in soybean areas based on measurements of soil-plant-atmosphere system and UAV images

Abstract

The identification of stress conditions in soybean crops is, in most cases, inaccurate, since they may not be noticeable to their full extent if only walking observations are carried out in the crop fields. This study aimed to identify the stress conditions in soybean crops, in three growing environments, in the Minas Gerais state, Brazil, using image processing techniques obtained by UAV, leaf and soil sensors, and climate data. The surveys encompassed two growth stages [beginning of blooming (R1) and beginning of seed enlargement (R5)] and consisted on UAV flights; mapping of chlorophyll content, soil moisture and soil pH; in addition to climate data. The HSV and yCbCr color models applied to RGB images showed the best Kappa accuracy index for the identification of crop features. The soil pH and moisture (water availability), solar radiation and temperature affected the crop growth and development in the study regions, in the R1 and R5 reproductive stages. However, the soil pH had less influence than the climatic variables. The R5 stage showed a greater vulnerability to stress caused by soil moisture and temperature.

Remote Detection of Water and Nutritional Status of Soybeans Using Uav-Based Images

“…The effect of droughts on soybean yields depends on the severity, duration, and timing of stress regarding the crop growth stage (Brar et al, 1990). Soybean is most susceptible to drought stress during its reproductive stage (Wijewardana et al, 2018(Wijewardana et al, , 2019b; however, when under long-term severe water stress during vegetative growth, substantial yield losses can be caused (Machado et al, 2020).…”