Effects of enhanced UV-B on growth and yield of two Syrian crops wheat (Triticum durum var. Horani) and broad beans (Vicia faba) under field conditions

The effects of enhanced W-B (280-320 nm) on the different phenological stages of a drought-resistant cultivar of wheat (Triticum durum var. Horani) and a drought-sensitive cultivar of broad beans (Vicia faba) under field conditions were investigated. Both species were exposed to a daily W-B dose 20% above the ambient UV-B simulating a 10% ozone reduction from germination to harvest. This dose ranged between 1.34 J/cm(2) at the beginning of the study and 6.33 J/cm(2) at the end of it. Plant height, tiller number, dry mass and leaf area in both species showed significant positive responses to UV-B treatment during the vegetative growth stages. At harvest, the seed mass of broad beans was nearly equal in exposed and unexposed plants, whereas in wheat, the grain mass and number of spikes increased significantly. This may support our hypothesis that a drought-resistant species (wheat) may exhibit greater protection against UV-B damaging effects compared to a drought-sensitive species (broad beans). (C) 1998 Elsevier Science B.V. All rights reserved.