CHAPTER FORTY THREE Effects of Hypergravity on the Chlorophyll Content and Growth of Root and Shoot During Development in Rice Plants Pandit Vidyasagar, Sagar Jagtap, Amit Nirhali, Santosh Bhaskaran, and Vishakha Hase Abstract Earlier studies on hypergravity effects showed modification in the metabolism of cell wall components, promotion of metaxylem devel- opment and decrease in extensibility of secondary cell walls in Arabidopsis thaliana (Tamaoki et al. 2006; Nakabayashi et al. 2006). In the present study, the effects of hypergravity on rice seeds which were exposed to hypergravity conditions and grown under normal gravity have been studied. Rice seeds (PRH-10 obtained from National Seeds Corporation, Govt. of India) were suspended in water in a test tube and were exposed to hypergravity ranging from 500–3,000 g for 10 min. Seeds exposed to hypergravity were grown on 0.8% agar under ambient conditions and light intensity of 1,250 Lux for 16 h per day. Seeds unexposed to hypergravity grown under the same conditions acted as control. Length of roots and shoots were measured. Chlorophyll was extracted on the fifth day and absorption and fluorescence spectra were recorded in both control and hypergravity samples. The cross sections of the roots were obtained and studied under the microscope. The results obtained showed that the chlorophyll content was less in the samples exposed to hypergravity. The roots showed changes in the diameter of cells at the core. To the best of our knowledge, such type of study has been reported for the first time. Keywords Hypergravity, rice, absorbance, fluo- rescence, chlorophyll content, root structure Introduction Studies carried out earlier shows that stem elonga- tion in Arabidopsis thaliana inflorescence stems was suppressed while dry weight of the inflores- cence stems increased in hypergravity (Tamaoki et al. 2006; Nakabayashi et al. 2006). Root length and fresh weight of roots and epicotyls of pea decreased as g increased (Waldron and Brett 1990). Similar results have been obtained for azuki bean epicotyls (Koizumi et al. 2007) and wheat coleoptiles (Wakabayashi et al. 2005). Primary and secondary cell wall contents (Tamaoki et al. 2006; Nakabayashi et al. 2006) and shoot diam- eter (Nakabayashi et al. 2006) were increased in hypergravity. However, hypergravity reduced cell J.F. Allen, E. Gantt, J.H. Golbeck, and B. Osmond (eds.), Photosynthesis. Energy from the Sun: 14th International Congress on Photosynthesis, 1599–1602. © 2008 Springer. Biophysics Laboratory, Department of Physics, University of Pune, Pune – 411 007, India