Variations in Achene Traits, Germination and Seedling Growth of Pluchea dioscoridis (L.) DC. As affected by Maternal Climatic Aridity

Abstract

The collection and germination of seeds for conspecific population distributed along climatic gradients can elucidate maternal environmental effects on achene traits, germination and seedling establishment and fitness. The current study explores this approach for the natural populations of Pluchea dioscoridis (L.) DC. (Asteraceae) which grows over a wide range of climatic regions in Egypt (Mediterranean, semiarid, and arid). The arid region showed the smallest achene size and pappus length, while the achenes size of Mediterranean region was > 36% and >27% larger than those of arid and semiarid regions, respectively. Generally, seed viability decreased with aridity and ranged from 41.96% at semiarid to 9.32% arid regions. Achenes from the three maternal climatic regions began germinating at approximately the same time, but germination rate proceeded differently. The achene germination percentage ranged from 10% to 33.54% for arid and semiarid regions, respectively. The study showed a significant effect of maternal climatic aridity on achene traits, germination rate and final germinating percentage of P. dioscoridis. However, survival rate of the three climatic regions was constant after 130 days of sowing. The results demonstrated how such widespread species acquire multiple maternal traits and mechanisms to optimize their adaptation, regeneration, and conservation of populations in stressful environments. However, further studies are required to demonstrate the phenotypic plasticity, reproductive efforts, and mechanism of dormancy loss of P. dioscoridis under different natural climatic conditions.