The effect of water stress on top and root growthin Medicago minima

Plants of Medicago minima var. minima grown in rootboxes of soil were subjected to water stress treatments in a growth chamber. The soil was returned to field capacity after drying cycles of 7, 14, 21, 28 or 35 days. After a 105-day-study-period water stress significantly decreased (p < 0•05) the rate of leaf production, live and total leaf number, total length of the central leaflet on live leaves per plant, branch and root segment production, and top and root dry weights. However, all plants remained alive, even those exposed repeatedly to −6•0 MPa. M. minima can thus survive under unfavourable environmental conditions and exploit abundant environmental resources when they are available.