Diurnal energy and water exchanges in bulrush millet in an area of high solar radiation

Begg, J.E. and Bierhuizen, J.F. and Lemon, E.R. and Misra, D.K. and Slayter, R.O. and Stern, W.R. (1964) Diurnal energy and water exchanges in bulrush millet in an area of high solar radiation. Agricultural Meteorology, 1 (4). pp. 294-312.

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The diurnalenergy and water relationships of a crop of bulrushmillet (Pennisetum typhoides S. et H.) were examined in an area of highsolarradiation at Katherine, N.T., Australia (latitude 14.3°S). The vertical distribution of the components contributing to the net upward water flux was evaluated by a simple heat-budget method from vertical profiles of net radiation, water vapour and temperature, as well as soil heat flux. The physiological response of the plant to diurnal changes in the environment was measured in terms of relative leaf water content, photosynthetic activity and stomatal aperture. The average illumination within the crop was obtained from light readings made with a flat surface and an omnidirectional photometer in vertical profiles during the day. The total dry matter and leaf area in the crop profile were determined from stratified samplings. Soil water relationships were also evaluated. At the time of the study, the soil water content in the surface 150 cm of soil was approaching the −15 bar value. A decrease in transpiration and an increase in sensible-heat loss demonstrated a marked influence on the energy balance by stomatal closure during the middle of the day. During the recovery period in the afternoon, transpiration increased, at a time when net radiation was decreasing, by gaining advected sensible heat from the atmosphere and also from the lower leaf layers. The fraction of net radiation utilized for transpiration generally decreased with depth into the plant canopy. It is postulated that both physiological and meteorological factors contribute to this phenomenon. The maximum proportion of direct evaporation from the soil in relation to the total evaporation appeared to be about 10%.

Item Type: Article
Author Affiliation: Divison of Land Research and Regional Survey, C.S.I.R.O., Canberra Australia.
Subjects: Atmosperic Science > Climatology
Atmosperic Science > Meterology
Plant Production > Croping Systems
Plant Production > Production Practices
Divisions: Millet
Depositing User: Library ICRISAT-InfoSAT
Date Deposited: 23 Mar 2012 09:49
Last Modified: 23 Mar 2012 09:49
Official URL: http://dx.doi.org/10.1016/0002-1571(64)90037-8
URI: http://eprints.icrisat.ac.in/id/eprint/4077

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