Photosynthesis of flag leaves and ears of field grown barley during drought
1994
Mogensen, V.O. | Mortensen, G. | Jensen, C.R.
A barley crop (Hordeum distichum L., cv. Corgi) was grown in sandy loam soil in lysimeters. The lysimeter installation was placed in the field and automatically protected from rain by a mobile glass roof. During the grain filling period, the plants were exposed to different levels of water stress expressed as the number of stress days (SD) calculated from the evapotranspiration of the water stressed and the fully irrigated crop. During this period, net photosynthesis of flag leaves and ears was measured between 1000 h and 1500 h. When the crop had utilized 2/3 of the available soil water content net photosynthesis began to decrease. With further decrease in soil water content, the relationship between photosynthesis of fully irrigated plants (Pr) and water stressed plants (Pa) decreased by 3 per cent for a decrease of 1 per cent in relative soil water content. When SD exceeded 1.8, Pa/Pr decreased by 7.1 per cent per SD. Relative grain dry matter and relative total dry matter yield decreased by 2.2 and 1.9 per cent per SD, respectively.
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