Monitoring water stress responses of Ipomoea Aquatica (Forssk.) by thermal imaging in different soil matierals of Northern Thailand
- Publikations-Art
- Kongressbeitrag
- Autoren
- Schulze, K; Wanwisa, J; Spreeer, W; Ongprasert, S; Wiriya-Alngkorn, W; Müller, J
- Erscheinungsjahr
- 2011
- Tagungsname
- Tropentag 2011
- Tagungsort
- Bonn
- Tagungsdatum
- October 5 - 7, 2011
- Schlagworte
- Wasserstreß
Water morning glory, Ipomoea aquatica (Forssk.), is a widely used leafy vegetable throughout Southeast Asia and China. The fast growing plant produces high biomass with a soft watery tissue. This study focuses on the responses of water morning glory to water deficit under controlled conditions.
Two cemented soil basins (8 m x 1 m x 1 m) under a plastic shelter were filled with soil material representative for Northern Thailand, taking care that the natural layering and bulk density was altered to the least extend possible. The original soil bodies were Regosol (a well-drained loamy sand developed on a middle terrace) from Mae Jo, Sansai District and Vertisol (a brown, clayey alluvial soil deposited on flood plain) from Mae Ai District.
I. aquatica (cv. ‘Reptan’) was planted and three weeks drip irrigated keeping the soil close to field capacity (Weather data were collected on site and matric potential was monitored with tensiometers. Stomatal resistance was determined once a day by a porometer (Decagon SC-1) and thermal images were acquired with an IR-camera (Infratec Variocam) at the same time. Crop water stress index (CWSI) was calculated as (TC - Tbase) / (Tmax - Tbase), where TC is the mean canopy temperature, Tmax is the upper threshold temperature of leaves where transpiration is suppressed by vaseline coating and Tbase is the temperature of water sprayed leaves and therefore the threshold for maximum evaporative cooling. After ten days of drought the plant material was harvested for determining above ground fresh and dry biomass.
CWSI based on thermal imaging showed a higher correlation with matric potential as with stomatal resistance. It was possible to visualize the differences between well-watered and stressed plants by thermal imaging before visible signs of wilting started.