Effects of Short-term Hypergravity Exposure on Germination, Growth and Photosynthesis of Triticum aestivum L.

Numerous studies have been carried out to investigate the hypergravity effect on plants, where seedlings (4-5 days old) were continuously exposed and grown under hypergravity condition. Here, we have used a novel 'shortterm hypergravity exposure experimental method' where imbibed caryopses (instead of seedlings) were exposed to higher hypergravity values ranging from 500 g to 2500 g for a short interval time of 10 minutes and post short-term hypergravity treated caryopses were grown under 1 g conditions for five days. Changing patterns in caryopsis germination and growth, along with various photosynthetic and biochemical parameters were studied. Results revealed the significant inhibition of caryopsis germination and growth in short-term hypergravity treated seeds over control. Photosynthesis parameters such as chlorophyll content, rate of photosynthesis (P-N), transpiration rate (Evap) and stomatal conductance (Gs), along with intracellular CO2 concentration (C-int) were found to be affected significantly in 5 days old seedlings exposed to short-term hypergravity treatment. In order to investigate the cause of observed inhibition, we examined the alpha-amylase activity and antioxidative enzyme activities. alpha-amylase activity was found to be inhibited, along with the reduction of sugars necessary for germination and earlier growth in short-term hypergravity treated caryopses. The activities of antioxidant enzymes such as catalase and guaiacol peroxidase were increased in short-term hypergravity treated caryopses, suggesting that caryopses might have experienced oxidative stress upon short-term hypergravity exposure.