Heteropogon contortus BL-1 (Pilli Grass) and Elevated UV-B Radiation: The Role of Growth, Physiological, and Biochemical Traits in Determining Forage Productivity and Quality

Exposure to elevated UV-B (eUV-B) is well known for its phytotoxicity, although studies made with UV-B exposure and its impact on grasses are limited especially from tropical countries including India. In this study, responses of a valuable grass species, Heteropogon contortus BL-1, were assessed under eUV-B (over ambient UV-B) at different growth stages. Damage caused by eUV-B was observed in the form of membrane damage and loss of pigments at early stages of growth, whereas tannin, phenol, and protein contents showed their increments at all the growth stages, to overcome the imposed stress. Reducing sugar showed its decline at all the growth stages, whereas starch and sucrose contents were higher mostly at later ages of plant growth. eUV-B caused a marked variations in anatomical structures with increase of mesophyll and spongy parenchymatous cells in leaves to reduce severity of irradiation, to maintain the growth and productivity. The study also highlights the significant negative influence of eUV-B on the growth of H. contortus BL-1 and its adaptive strategy to minimize the negative impacts. With the progression of age, plants although adopted to UV-B stress with maintenance of productivity, but palatability of forage was affected due to increment of tannin content.