Variation in total polyamine content in some native rice cultivars of North Kerala, India in response to salinity stress

Phytohormone like low molecular weightaliphatic polycationic compounds known as polyamines have an essential role inplant growth and development and they respond to various environmental stress factors. Maintaining crop yields under adverse environmental stresses is a major challenge facing modern agriculture where polyamines play an important role. The total polyamine content in some native rice cultivars of North Kerala under salinity stress has been analysed presently and the results show that the total polyamine content in all the cultivars got increased in relation to the increase in the salt concentration applied. The highest total polyamine content was noted in the cultivar Orkazhama followed by Kuttusan and Kuthiru which were collected from a traditional saline rice tract of North Kerala. The highest percentage of increase in total polyamines was noted in the cultivar Kunhutty followed by Kuttusan and Veliyan.Kunhutty and Veliyan are cultivars collected from a non saline rice tract. In all the cultivars the total polyamine content got increased starting from the 10mM NaCl treatment itself. Among the cultivars studied, Orthadian showed the lowest amount of total polyamine content and Kuthiru showed the lowest percentage of increase in relation to increase in salinity. This result shows that salinity induces the accumulation of polyamines in rice plants and this may be a mechanism to contribute tolerance and resistance to salt stress. The rate of variation is cultivar specific. Identification of suitable genotypes and their improvement can be used as a potential method to evolve salinity resistant rice genotypesfor different geographical zones.