
%0 Journal Article
%A Singh, DhananJay K. 
%A Sale, Peter W. G. 
%A McKenzie, Blair M. 
%T Water relations of white clover (<emph type="2">Trifolium repens</emph> L.) in a drying soil, as a function of phosphorus supply and defoliation frequency
%J Australian Journal of Agricultural Research
%D 1997/06/04
%V 48
%N 5
%P 675-682
%K leaf water potential, soil matric potential, water stress symptoms, evapotranspiration.
%R https://doi.org/10.1071/A96156
%U https://www.publish.csiro.au/paper/A96156 
%X A glasshouse pot experiment was carried out to determine how white clover plants responded to repeated drying cycles, under conditions of varying P supply and defoliation frequency. Measurements included leaf water potential (&#936;leaf), evapotranspiration rate, soil matric potential (&#936;soil), an assessment of visual water stress symptoms, and the rate of plant recovery on rewatering. The rate of decline in &#936;leaf per unit decline in &#936;soil was greater in frequently defoliated plants. High-P plants extracted more water per unit time, were able to maintain a higher &#936;leaf in dry soil than low-P plants, displayed minimal water stress symptoms, and recovered completely on rewatering. High-P, frequently defoliated clover plants displayed minimal water stress symptoms in dry soil, whereas frequently defoliated low-P plants showed extreme symptoms; these plants were unable to recover from severe water stress and most plants died during the final drying cycle. Infrequently defoliated, low-P plants partially recovered from the water stress condition, but the recovery was slower than that for infrequently defoliated high-P plants. The findings suggest that the combination of dry soil, low P supply, and frequent defoliation that would result from heavy grazing would threaten the survival of white clover plants in the field. 
