干旱区生态环境知识资源中心

Two annuals from the Negev Desert, Plantago coronopus and Anastatica hierochuntica, were grown outdoors under two irrigation regimes and photoperiod treatments of 16, 12 and 8 h, and natural daylength. Measurements included whole plant mass, resource allocation, fitness payoff, maternal effects of daylength and water regimes on seed germination. In both species seed germination percentages were affected by maternal and environmental factors. P. coronopus showed higher plasticity according to the daylength; plants under long days were larger and produced more seeds that germinated to higher percentages. The plasticity shown in A. hierochuntica correlated mainly to water regime and less to daylength. Both species are common in the and environment, but P. coronopus, which has a stronger response to daylength, is more widely distributed. (C) 2003 Elsevier Science Ltd. All rights reserved.