Relationships between Reflectance and Water Status in a Greenhouse Rocket (Eruca sativa Mill.) Cultivation

Abstract

Crop water status is an important parameter for plant growth and yield performance in greenhouses, and thus early detection of water stress is essential for efficient crop management. Therefore, the aim of this work was to study the relationship between crop reflectance and common soil and crop water status indicators. Two different irrigation regimes, namely 50 and 100 % of the crop potential evapotranspiration were imposed to rocket plants (Eruca sativa Mill.) grown in pots filled with soil inside a greenhouse. Leaf area index and mid-season crop coefficient, which are essential for irrigation schedulling were estimated. Crop reflectance indices were calculated using the radiation reflected by the crop in 8 narrow wavelength bands (10 nm in width), centred at 460, 510, 560, 610, 660, 710, 760 and 810 nm. Canopy reflection measurements were carried out during July and August 2010 in a greenhouse located in Arta, Greece. The results showed that crop reflectance to radiation ranging from 510 to 710, and at 810 rim, is strongly related to water stress in rocket plants. Crop reflectance has not been extensively studied under greenhouse conditions and seems to be a promising, easy-to-use, non-contact and non-destructive tool for crop water status assessment.