Natural Ultra Violet Radialtion on Field Grown Rice (Oryza sativa L.) Plants Confer Protection against Oxidative Stress in Seed during Storage under Subtropical Ambience

Abstract

While heat and humidity are known for causing oxidative macromolecular cell damage related seed deterioration during storage under subtropical conditions, information on effect of UV radiation that is also known to cause bio-molecular as well as direct hit damage in plants is largely lacking. A study involving measurements of UV irradiance in seed storage and also over open fields during seed maturation reveals an inverse correlation between genetically conferred (varietally expressed) content of non-enzymatic antioxidant viz flavonoids (functioning also as successors) and seed deterioration during post harvest storage. The data shows that extent of cell damage and thus seed viability is related to the varietal difference in flavonoids accumulation in mature rice seed. Low storer/viable varieties show lower content of flavonoids and higher oxidative damage in stored seed.

The effect of natural long-term packaging methods on antioxidant components and malondialdehyde content and seed viability Moringa oleifera oilseed

“…As the level of ROS increases, antioxidants degradation exceeds its synthesis and the levels decrease and consequently ROS might continue to accumulate above the critical threshold (Munneé-Bosch. 2005;Shahidi et al, 2006) An increase in MDA during seed storage was reported in many studies (Rao et al 2006;Choudhury and Mandi, 2012) and was indicated to increase gradually with the loss of seed viability. Similarly to the present study, De Oleiveira (2017) found that lipase activity of Moringa seed stored 4°C and 27°C did not change until 12 months of storage but observed a degradation of storage lipids at 18 months of storage.…”

“…Based on fatty acid composition of oil (77% m11onounsaturated, 2% polyunsaturated and 22% saturated) extracted from M. oleifera seed (Lalas and Tsaknis, 2002), it is clear that the seed contains less polyunsaturated fatty acids which are prone to lipid peroxidation. This might be the reason behind the slow increase of MDA in stored Moringa seed compared to other species such as cotton (Goel and Sheoran, 2003) and Oryza sativa L. (Choudhury and Mandi, 2012) where an increase of more than two fold (compared to initial level) was recorded within 24 months or less of storage.…”

“…A closer look at different treatments revealed that seed stored in paper bags at 20 and 30°C had the lowest moisture content, the lowest flavonoids content and the highest germination % at 24 months of storage. Flavonoids have been suggested to prevent seed deterioration by removing reactive oxygen species (ROS) and thereby preventing ROS from damaging cellular bio-molecules (Choudhury et al, 2012). Although there is no clear explanation behind this relationship, it is possible that the low moisture content lead to low water activity, restraining the accumulation of ROS and the synthesis of flavonoid in seed.…”

“…Studies (Tommasi et al, 2006;Puckaka and Ratajckak, 2005;Choudhury and Mandi, 2012) have related the decline of seed viability, associated with ageing, to the decrease in antioxidant defence mechanisms as well as the decrease in some secondary metabolic compounds that have antioxidative properties. Malondialdehyde (MDA) produced during reactive oxygen species reaction, is an indicator of oxidative damage (Bailly et al 1996).…”