Crop Water Stress Index for a medicinal plant ( Spreng.) Baccharis crispa under variable irrigation levels

Abstract

There are different techniques for water stress detection in plants and the use of new technologies becomes an essential tool for the development of precision agriculture. One of these technologies is the use of indicators derived from non-contact sensors as infrared thermography. In this study, the (CWSI) was evaluated for a medicinal plant 'carqueja' Crop Water Stress Index ( Spreng.), using canopy temperature data obtained with a hand-held infrared thermometer (IRT). The study was Baccharis crispa carried out under greenhouse conditions at the ESALQ/USP, in Piracicaba, São Paulo State, Brazil. Plants were grown in 11 L pots in a soil classified as Typic Hapludox. The experimental design was completely randomized with 6 blocks and 6 treatments of irrigation levels: 25, 50, 75, 100, 125 and 150% of the reference vapotranspiration (ETo) applied for 180 days. CWSI was calculated with data of leaf temperature and air temperature. The analysis of means was performed by Tukey test at 0.05 probability. It was concluded that treatments under 25 and 50% ETo showed higher leaf temperature and, consequently, higher CWSI, so infrared thermometry can be used as an alternative for the fast and reliable management of irrigation in medicinal plant 'carqueja'.