ARTICLE Effects on rice plant morphology and physiology of water and associated management practices of the system of rice intensification and their implications for crop performance Amod K. Thakur • Sreelata Rath • D. U. Patil • Ashwani Kumar Received: 17 August 2010 / Revised: 1 November 2010 / Accepted: 1 November 2010 / Published online: 17 November 2010 Ó Springer-Verlag 2010 Abstract Field experiments were conducted in Bhu- baneswar, Orissa, India, during the dry season (January– May) in 2008 and 2009 to investigate whether practices of the System of Rice Intensification (SRI), including alter- nate wetting and drying (AWD) during the vegetative stage of plant growth, could improve rice plants’ morphology and physiology and what would be their impact on resulting crop performance, compared with currently rec- ommended scientific management practices (SMP), including continuous flooding (CF) of paddies. With SRI practices, grain yield was increased by 48% in these trials at the same time, there was an average water saving of 22% compared with inundated SMP rice. Water productivity with AWD-SRI management practices was almost doubled (0.68 g l -1 ) compared to CF-SMP (0.36 g l -1 ). Significant improvements were observed in the morphology of SRI plants in terms of root growth, plant/culm height, tiller number per hill, tiller perimeter, leaf size and number, leaf area index (LAI), specific leaf weight (SLW), and open canopy structure. These phenotypic improvements of the AWD-SRI crop were accompanied by physiological changes: greater xylem exudation rate, crop growth rate, mean leaf elongation rate (LER), and higher light inter- ception by the canopy compared to rice plants grown under CF-SMP. SRI plants showed delayed leaf senescence and greater light utilization, and they maintained higher pho- tosynthetic rates during reproductive and grain-filling stages. This was responsible for improvement in yield- contributing characteristics and higher grain yield than from flooded rice with SMP. We conclude that SRI prac- tices with AWD improve rice plants’ morphology, and this benefits physiological processes that result in higher grain yield and water productivity. Keywords System of rice intensification (SRI)  Phenotype  Management practices  Water productivity  Physiology Introduction Agriculture faces two major challenges. First, it needs to enhance food production sustainably to feed a growing world population; at the same time, this increase needs to be accomplished under conditions of increasing scarcity of water resources (Bouman 2007). Rice (Oryza sativa L.) is the foremost staple food for more than 50% of the world’s population. It is estimated that by the year 2025, the world’s farmers should be producing about 60% more rice than at present to meet the food demands of the expected world population at that time (Fageria 2007). Irrigated rice production is the largest consumer of water in the agri- cultural sector, and its sustainability is threatened by increasing water shortages. Such water scarcity necessi- tates the development of alternative-irrigated rice systems that require less water than traditional-flooded rice (Bou- man et al. 2005). Researchers have been developing various water-saving technologies, such as alternate wetting and drying (Bou- man and Tuong 2001; Belder et al. 2004, 2007; Zhang et al. A. K. Thakur (&)  S. Rath  D. U. Patil  A. Kumar Directorate of Water Management, Bhubaneswar, Orissa, India e-mail: amod_wtcer@yahoo.com S. Rath e-mail: sreelata.rath@gmail.com D. U. Patil e-mail: patildu_wtcer@yahoo.com A. Kumar e-mail: ashwani_wtcer@yahoo.com 123 Paddy Water Environ (2011) 9:13–24 DOI 10.1007/s10333-010-0236-0