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Report, 1992

Dygnsvariation i bladvattenpotential hos raps och senap: mätningar och simuleringar

Burujeny; Mohammad, B


During the summer 1991 a project about Brassica sortes was carried out. The experiment was conducted under a shelter under field conditions at the Swedish University of Agricultural Sciences, Uppsala. The aim was to see differences in behavior between different species regarding the influence of drought conditions. The leaf water potential and leaf-air temperature difference are indications of plant reaction. Measurements were made during one day (l august 1991) of leaf water potential and soil water potential. Also a minor investigation of leaf-air temperature differences was made. The leaf water potential was also simulated with a transpiration model (SPAC) which describes the pathway of water from the soil to the atmosphere. There are different resistances (soil-root resistance, plant resistance, stomata resistance and acrodynam1c resistance). To enable movement of water, a potential difference is needed. It is based on the same principles as Ohm's law. The rate of now is the ratio between the potential difference and the resistance. The resistances are depending on climate factors (global radiation, air relative humidity, air temperature, wind speed and precipitation). Soil-root resistance depends also on soil conditions and the plant resistance is controlled by the morphological and physiological condition of the plant. The results obtained from simulation with the SPAC - model, based on climatic data, were compared with the measurements of the leaf water potential. The results from the model corresponded with the measurements done on the irrigated plots when the plant resistance was low (5MPa s m2 g-l). The water potential measured on the stressed plot became lower. We noticed that the soil water potential was lower and concluded that the soil-root resistance remained at about the same low level as for the irrigated plots. It was also shown that the SPAC-model simulation was not able to give good agreement with the measured leaf water potential and the measured leaf air temperature difference simultaneously. From the point of view of the theory represented by the model at least one of the I11casurments must have been wrong. Il should bc possible in the future to improve and/or replace manual measurement techniques with the SPAC - model


Brassica; vattenbrist; avkastning; bladvattenpotential; simulering; försök

Published in

Avdelningsmeddelande / Sveriges lantbruksuniversitet, Institutionen för markvetenskap, Avdelningen för lantbrukets hydroteknik
1992, number: 92:3
Publisher: Institutionen för markvetenskap, avdelningen för lantbrukets hydroteknik, Sveriges lantbruksuniversitet

UKÄ Subject classification

Fish and Aquacultural Science
Agricultural Science

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