Effect of acute gamma radiation on the first generation of wheat grains: Effect of acute gamma radiation on the first generation of wheat grains: Comparison with space varieties

In this thesis the effect of radiation on the nutritional values of wheat seed (Triticum aestivum L., cv. Servus 40 ) is investigated and compared with wheat varieties specifically selected for growing in space conditions: Apogee and Perigee wheat. Bringing wheat seeds to Mars has multiple advantages. Due to limited storage in a rocket that will take humans to Mars, only a limited supply of food can be brought along and resupply missions will not be possible. This is a problem because a journey to Mars can only be made every 2 years. Astronaut food has a high amount of nutrients and a long shelf life but is not very tasty. Therefore, certain seeds, such as wheat seeds are being looked at to bring along on the journey to Mars to enable cultivation of fresh food. These seeds can be grown in a closed environment and can be used to make bread and other products. In bringing along these seeds, astronauts can have more variation in the food they eat, the astronauts can take care of the plants when they are growing and prepare their own food with them which is good for their psychological wellbeing. One of the factors that could influence the quality of the seeds on a journey to Mars are the increasing amounts of radiation they will be exposed to. In this study, gamma radiation is used to irradiate the seeds. This type of radiation is chosen as an alternative to cosmic radiation. Different dose rates are tested: 43,4 mGy/h, 106 mGy/h, 173 mGy/h, 427 mGy/h and 4320 mGy/h. In this study from the irradiated seeds plants are cultivated and, the seeds that this first generation of plants produce are being analysed. The goal is to understand the effect of radiation during storage of wheat seeds and how it differs in multiple varieties. The main focus was on the nutritional quality of the seeds obtained in the first generation as this will be the end product the astronauts will produce on Mars. Within this study a number of parameters that determine wheat nutritional value were analysed. As such, the amount of proteins were determined using the Kjeldahl procedure. Ammonium content was measured using the continuous flow analyser (Skalar). Total nitrogen and carbon content were measured by use of the elemental analyser (Flash). Starch damage and alpha-amylase were measured by use of a Megazyme kit. Starch was measured by use of anthrone reagent and antioxidant capacity was determined by using the Ferric Reducing Antioxidative Power (FRAP) assay. Using different radiation doses resulted in significant differences between irradiated seeds with values often being lower than the control and levels between each other varying per dose rate received. Seeds coming from plants from the lowest tested radiation level (43,4 mGy/h) often showed an increase in the tested nutritional value in comparison to the control whereas higher radiation doses resulted in progeny of seeds of lesser quality compared to control seeds. Both Perigee, Apogee and Servus have advantages and disadvantages. For example Servus a greater yield of edible biomass even from the seeds that were irradiated with the highest dose (427 mGy/h) but the amount of protein in the control is to low to make good quality bread. Apogee has a higher protein amount but less starch and Perigee having a higher starch level but needing more time to grow to maturity than the other seeds. It is not clear from the results which of the two is the most suitable candidate for the mission to Mars. Thus, further studies are needed to conclude which of the two varieties is a better candidate crop for human-crewed space missions.