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

Abstract

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.

Effect on essential oil components and wedelolactone content of a medicinal plant Eclipta alba due to modifications in the growth and morphology under different exposures of ultraviolet-B

“…Singh et al (2008) also found shorter plants with reduced leaf area in Vigna unguiculata due to eUV-B treatments. Similarly, the retardation was also reported in Heteropogon contortus (Hamid et al 2019); Phaseolus vulgaris (Singh et al 2014), Fagopyrum esculentum (Regvar et al 2012) and Abelmoschus esculentus (Kumari et al 2009b) under UV-B stress. Reduction in plant growth was probably not only due to the destruction of endogenous IAA concentration on the shoot tips by UV-B induced photodegradation but may also be due to alternation in transport of auxin and excessive oxidative stress resulted in a decline in overall plant stature and photosynthesis (Takshak and Agrawal 2018).…”

Effects of plant age on performance of the tropical perennial fodder grass,Cenchrus ciliarisL. subjected to elevated ultraviolet‐B radiation

“…Several studies have assessed the effects of elevated UV‐B on crop plants, but data are limited for non‐crop plants (Sullivan et al , 1992). Hamid et al (2018) are the only group to assess the response of an Indian grass ( Heteropogon sp.) to UV‐B.…”

“…Elevated UV‐B exerts several structural, biochemical and physiological effects on plants (Bancroft et al , 2007). High doses of UV‐B can lead to damaged membranes from accumulation of reactive oxygen species (ROS) ( Choudhary & Agrawal, 2014a,b; Hamid et al , 2018). To alleviate UV‐B stress, plants synthesize secondary metabolites, mainly phenolics, flavonoids and hydroxycinnamate esters, which accumulate in vacuoles of epidermal cells and can attenuate penetration of UV‐B into deeper photosynthetic tissues (Frohnmeyer & Staiger, 2003).…”

“…To alleviate UV‐B stress, plants synthesize secondary metabolites, mainly phenolics, flavonoids and hydroxycinnamate esters, which accumulate in vacuoles of epidermal cells and can attenuate penetration of UV‐B into deeper photosynthetic tissues (Frohnmeyer & Staiger, 2003). Induction of enzymatic and non‐enzymatic antioxidants and proline can help to mitigate the harmful effects of UV‐B‐induced ROS accumulation (Hamid et al , 2018). UV‐B significantly enhances antioxidant enzyme activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as concentrations of H 2 O 2 and malondialdehyde (MDA) in Pill grass (Hamid et al , 2018).…”

“…Induction of enzymatic and non‐enzymatic antioxidants and proline can help to mitigate the harmful effects of UV‐B‐induced ROS accumulation (Hamid et al , 2018). UV‐B significantly enhances antioxidant enzyme activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as concentrations of H 2 O 2 and malondialdehyde (MDA) in Pill grass (Hamid et al , 2018).…”