Moisture stress effects on biomass partitioning in two Sonoran Desert annuals.

Seasonal growth rates were modified by water input, and for all water input treatments Schismus barbatus grew more rapidly than Plantago insularis. As the growing season progressed and ambient temperature rose, incremental water input had an inverse effect upon relative root growth of both species. Relative foliar growth rate was not markedly altered by water input. When reproductive structures were present, their growth rates were higher than those of vegetative structures in both species. Schismus responded to water input by significantly increasing the biomass allocated to reproduction, which increased relative reproductive allocation. The computed reproductive allocation of Plantago is not correlated with water input, although the ultimate reproductive biomasses were correlated with the summation of plant moisture stress during reproduction.-from Authors