Impact of seed exposure to simulated microgravity on growth and development in tomato (Solanum lycopersicum L.)

Abstract

The study titled “Impact of seed exposure to simulated microgravity on growth and development in tomato (Solanum lycopersicum L)” was undertaken with the objective to evaluation of morpho-physiological, anatomical and biochemical changes in growth and development in tomato after exposure of seeds to different simulated microgravity. The experiments were conducted using seeds of the tomato variety 'Anagha,' which were exposed to simulated microgravity conditions. Microgravity is characterized by a reduction in gravitational force, which can create stress in organisms and plants, affecting their metabolism, growth, and development. Simulated microgravity was created using a Random Positioning Machine (RPM), which rotates seeds slowly at speeds of (25-40 rpm), reducing the effect of gravity to around 10-3 g. Seeds were exposed to (4hr, 8hr, 12hr, 24hr and control different durations of simulated microgravity. Two experiments were carried out in a completely randomized design (CRD). In both experiments, the seeds were sown, and the seedlings were transplanted into pots 30 days after sowing. They were maintained under standard cultural practices, including irrigation. The study was conducted across two growing seasons: Summer and Kharif. The results revealed that exposure to simulated microgravity significantly influenced tomato growth. The simulated microgravity treatment (T4) enhanced the germination rate, which reached (95%) in the summer and (97%) in the kharif season by the seventh day. Additionally, treatment (T3) exhibited the highest seedling vigor in the summer (13.75), while treatment T4 showed the highest seedling vigor in the kharif season (15.32). Moreover, treatment T4 also displayed the highest germination speed in both seasons. In the summer, the earliest flowering occurred in treatment T4 (23.5 DAT), while in the kharif season, treatment T3 exhibited early flowering (24.75 DAT). The pollen viability in treatment T4 was enhanced, exceeding (80%) during the kharif season. Furthermore, the study reported an increase in chlorophyll content under simulated microgravity conditions, with treatment T4 reaching (1.785 mg/g) in the kharif season. Various enzymatic activities, such as peroxidase, superoxide dismutase, and catalase, increased, while malondialdehyde (a marker of lipid peroxidation) also increased. These responses suggest that the plants developed better stress tolerance under microgravity conditions. The study found that simulated microgravity significantly influenced various growth and biochemical parameters in tomato plants. In the summer season, treatment T1 showed the highest ascorbic acid content (12.62 mg g-1), plant height (87.175 cm), fresh weight (378.75 g), and root growth. In the kharif season, treatment T3 exhibited the highest ascorbic acid content (20.37 mg/g-1), anthocyanin (0.448 mg/g), and total sugar content (1.305 mg/g), while treatment T4 had the highest lycopene content (3.143 µg/g), plant height (98.4 cm), and yield (842.25 g). Root length, volume, fresh, and dry weight were significantly enhanced under treatment T3 in the kharif season. Overall, seeds exposed to simulated microgravity showed increased growth, improved biochemical composition, and enhanced fruit yield, highlighting the potential of microgravity as a tool for crop improvement in both terrestrial and extraterrestrial agriculture. In conclusion, this study demonstrates that simulated microgravity has a positive impact on the growth, development, and biochemical characteristics of tomato plants. Improved germination rates, enhanced seedling vigor, increased chlorophyll content, and higher yields were observed, suggesting that microgravity could be a useful tool for crop improvement. Furthermore, increased enzymatic activity and better root growth under stress conditions indicate the potential applications of simulated microgravity in agriculture, both on land. This is the first of its kind of study performed on Anagha seeds and such studies on other species developed within KAU can lead to interesting results and important clues on enhancing crop yield and productivity. Future research should focus on long-term exposure to simulated microgravity and its effects on other crop species. This knowledge can help optimize crop production in space missions and challenging terrestrial environments, contributing to sustainable food security on earth and beyond.