Cellular processes, signaled by UV radiation, contribute to the behavior of plants under various and different stresses in the environment. The importance of the free radical, nitric oxide (NO) was identified as a key early signal in this process. Stress-induced NO can be protective, produce physiological disorders, DNA damage, and programmed cell death (apoptosis). This volume is divided into three parts; Instrumentation and Ecological Aspects; which evaluates case histories, and introduces new instruments for the non-invasive sensing and imaging of UV-stress-related damage in vegetation; Effects of UV Radiation, Nitric oxide and Plant stress; this identifies the cell biological hazards of UV radiation coupled to other environmental stresses, and Plant Stress and Programmed Cell Death; Examining how UV light may relate to the production of NO by plants in terms of DNA damage, error-prone repair cell cycles, and the multiple mechanisms of programmed cell death. The main aim in this publication is to introduce new theoretical developments and instrumentation for cell biology, to update our understanding of the effects of UV radiation, and to evaluate how plants use UV signals to protect against damage and enhance their productivity.