Interesting , how are the plants are affected by sun radiation..These are : Chromosomal aberrations, defined as visually observable changes in chromosome structure; DNA damage, defined as any damage to DNA molecules, including DNA sequence "inversion" (TCAG now GACT) as well as sections of sequences being "deleted"; Growth reduction, defined as a reduction in the rate of growth of organisms; Reproduction effects, including sterility, reduction in reproduction rate, and occurrence of developmental abnormalities or reduction in viability of offspring;Reduced seed germination; mortality, including both acute lethality and long-term reduction in life span and  direct burn damage to exposed tissue. Based on discussion on  Effects of Radiation on Plants by  Reed Miller on  March 17, 2015

Please have a look at another very interesting work..

The effects of solar ultraviolet (UV)-B and UV-A radiation on the potential efficiency of photosystem II (PSII) in leaves of tropical plants were investigated in Panama (9°N). Shade-grown tree seedlings or detached sun leaves from the outer crown of mature trees were exposed for short periods (up to 75 min) to direct sunlight filtered through plastic or glass filters that absorbed either UV-B or UV-A1B radiation, or transmitted the complete solar spectrum. Persistent changes in potential PSII efficiency were monitored by means of the dark-adapted ratio of variable to maximum chlorophyll a fluorescence. In leaves of shade-grown tree seedlings, exposure to the complete solar spectrum resulted in a strong decrease in potential PSII efficiency, probably involving protein damage. A substantially smaller decline in the dark-adapted ratio of variable to maximum chlorophyll a fluorescence was observed when UV-B irradiation was excluded. The loss in PSII efficiency was further reduced by excluding both UV-B and UV-A light. The photoinactivation of PSII was reversible under shade conditions, but restoration of nearly full activity required at least 10 d. Repeated exposure to direct sunlight induced an increase in the pool size of xanthophyll cycle pigments and in the content of UV-absorbing vacuolar compounds. In sun leaves of mature trees, which contained high levels of UV-absorbing compounds, effects of UV-B on PSII efficiency were observed in several cases and varied with developmental age and acclimation state of the leaves. The results show that natural UV-B and UV-A radiation in the tropics may significantly contribute to photoinhibition of PSII during sun exposure in situ, particularly in shade leaves exposed to full sunlight.. Source ; Plant Physiology, December 1999, Vol. 121, pp. 1349–1358