By K.S.Jayaraman

Bengaluru, Feb 19 (IANS): Pre-treatment of maize seeds with a small dose of gamma radiation improves crop productivity and yield without using chemical fertilizers, scientists at the Indian Agricultural Research Institute (IARI) in New Delhi have found.

Reporting their findings in the Indian Journal of Experimental Biology, Achchhelal Yadav and co-workers say that their study has shown that exposing the seeds to gamma rays before sowing positively influenced the germination and vegetative growth of maize.

Among the cereals, maize accounts for nine per cent of India's total foodgrain production - but the productivity is low - only 2.5 tonnes per hectare. Thus, the study aimed to assess the effect of gamma rays "on growth, yield and physiological attributes of maize."

Gamma rays are emitted by radioactive nuclei, one such source being Cobalt-60 (Co-60), an isotope of the element Cobalt. For their study, the researchers obtained maize seeds from the National Seed Corporation of India in New Delhi and exposed them to various doses of gamma radiation from the Cobalt-60 source facility available in their institute.

The germination of the irradiated seeds was assessed in an incubator chamber and they were then sown during the kharif (July-October) seasons of 2013 and 2014 at the IARI research farm.

Data obtained from the experiment suggested that exposure to low dose gamma radiation increased the germination rate by 90 per cent, plant height by 17 per cent, and crop yield by 8.3 per cent compared to seeds that were not exposed to the gamma radiation.

According to the researchers, the gamma radiation-induced phenomena in the maize seeds "might be due to change in the ascorbic acid content, higher activation of ribonucleicacid (RNA) or protein synthesis of irradiated seeds".

"Their observation of radio stimulation at low doses of ionizing radiation is not new," P.C.Kesavan, a radiation biologist and Distinguished Fellow at the M.S. Swaminathan Research Foundation in Chennai, told this correspondent. "There are hundreds of papers published on this subject," he added.

The IARI scientists, however, report that exposure of seeds to gamma radiation before sowing and its influence on plant growth and yield assessment was not much studied in field experiments before, adding: "Therefore, the present study was planned and executed at field condition."