~ 318 ~ The Pharma Innovation Journal 2018; 7(6): 318-323 ISSN (E): 2277- 7695 ISSN (P): 2349-8242 NAAS Rating: 5.03 TPI 2018; 7(6): 318-323 © 2018 TPI www.thepharmajournal.com Received: 19-04-2018 Accepted: 20-05-2018 R Samundeswari Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India D Durga Devi Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India P Jayakumar Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India N Jeyapandiyan Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India Correspondence R Samundeswari Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India Assessment of biochemical basis of yield variation in small millets under rainfed condition R Samundeswari, D Durga Devi, P Jayakumar and N Jeyapandiyan Abstract Small millets are important climate-smart nutritious crops. Biochemical constituents play an important role in crop growth and development. Understanding the biochemical changes in crops plants at different stages helps to understand their adaptations to extreme climate changes and crop characteristics, their influence on grain yield. In this study, we assessed the biochemical constituents such as soluble protein, proline, nitrate reductase, catalase activity and peroxidase activity at five different growth stages (vegetative, flowering, grain development, grain maturity and harvest) and five small millets (foxtail millet, proso millet, kodo millet, little millet and barnyard millet). The proline accumulation was highest at grain development stage in all the small millets (1.43 to 2.02 mg/g) and was the maximum in barnyard millet. Soluble protein and nitrate reductase activity were the maximum in foxtail millet; both increased from flowering to grain development stages and decreased in later stages. Barnyard millet had the highest catalase activity in all five growth stages, followed by foxtail millet, and the lowest catalase activity was found in little millet across growth stages. Within each crop, a cultivar having high soluble protein, nitrate reductase, proline, and peroxidase activity had higher grain yield, while cultivar with high catalase activity had comparatively low yield, except little millet. Keywords: Proline, Soluble protein, nitrate reductase, catalase activity, peroxidase activity, small millets Introduction Small millets, such asfinger millet, foxtail millet, proso millet, kodo millet, little millet and barnyard millets are considered as important nutri-rich climate-smart crops (Vetriventhan and Upadhyaya 2015) [14] . The small millets are adapted to varied agro-climatic regions, and their use as food, feed and fodder make them important for food security (Upadhyaya et al. 2008) [13] . Small millets are suited to conditions of low and moderate rainfall area due to early maturity and their adaptation to water stress conditions. Besides India, small millets are also grown in China, Russia, Japan., USA and other African and East Asian countries. In India, the cultivation of small millets is confined to Andhra Pradesh, Karnataka, and Tamil Nadu.In India, small millets are cultivated in limited area of 2.32 m ha and occupy about 9.7 lakhs ha with a production of 4.67 lakhs tons, with a productivity of 480 kg/ha (averaged between 2006-2010). Potential yields of up to 3 tons in small millets were reported (http://www.aicrpsm.res.in/Reports.html), indicating a large yield gaps, and great opportunity to enhance productivity following improved crop management practices and cultivation high yielding cultivars. Various biochemical constituents play important role in crop growth and development, and their concentration varies at different growth stages and growing conditions (stress and non- stress). Comparative investigation on small millets, with respect biochemical traits and grain yields were meager. Assessing the change in biochemical constituents in small millets, and at different growth stages and the relationship with yield would help in understanding the basis of crop and varietal differences in terms of productivity. This study aims to assess the biochemical constituents such as soluble protein, nitrate reductase, proline, catalase and peroxidaseat five different growth stages and their influence on grain yields. Materials and Methods The experiment was conducted at Eastern Block Farm of Tamil Nadu Agricultural University, Coimbatore situated at 11Nº and 77Eº longitude with at an altitude of 426.7 m above mean sea level. This study included two cultivars each of barnyard millet (Co 1 and Co 2) and kodo millet (Co 3 and APK), three cultivars each of proso millet (Co 3, Co 4, and Co 5), little millet (Co2, Co 3 and Co4) and foxtail millet (Co 5, Co 6 and Co 7). Together, 13 cultivars of five small millets were planted