Physiological response of rice (Oryza sativaL.) genotypes to elevated nitrogen applied under field conditions

Abstract

Field experiment was conducted at G.B.P.U.A.T. Pantnagar, Uttarakhand, India in rainy season of 2008 and 2009 to study the impacts of increased nitrogen doses on growth dynamics, biomass partitioning, chaffy grain and nitrogen use efficiency in 4 rice genotypes viz., Vasumati, Tulsi, Kasturi and Krishna Hamsa. Four doses (N(0), N(50), N(100) and N(200) kg N ha(-1)) of nitrogen in the form of urea were applied in 3 split. Increased trend in growth dynamics during active tillering and flowering stage, and biomass partitioning at the time of active tillering and flowering stage was observed with respect to nitrogen doses. Chaffy grain number and chaffy grain weight per 5 panicles was significantly increased with enhancing nitrogen doses and was highest for Vasumati. Nitrogen use efficiency (NUE) was increased up to N(100) kg N ha(-1) and it was declined with rising nitrogen doses (N(200) kg N ha(-1)). The highest values for NUE was achieved by rice genotype Krishna Hamsa whereas lowest by Vasumati. In addition to this, a significant correlation between nitrogen doses and growth dynamics, biomass partitioning and chaffy grain was observed. These findings suggest that growth dynamics, biomass partitioning, chaffy grain could be enhanced by the input of high rate of nitrogen fertilizer but not nitrogen use efficiency. Therefore, this study is useful to screen most N efficient genotypes which can be strongly suggested to rice growers to enhance crop yield irrespective of use of high dose of N fertilizers.

Morpho-physiological and Biochemical Characterization of Rice (Oryza sativa L.) Genotypes under Ammonical and Nitrate form of Nitrogen

“…During wet season 2015, under irrigated condition average phenotypic value recorded in NH 4 + treatment for grain yield (g/m 2 ), biological yield (g/m 2 ), harvest index (%), Days to 50% flowering (days), plant height (cm), effective tiller/plant, total tiller/ plant was 284, 849, 34, 76.4, 106, 6.9 2 ), harvest index (%), Days to 50% flowering (days), plant height (cm), effective tiller/plant, total tiller/ plant was 89, 327, 27.9, 81, 89, 7.8 and 7.2, respectively. These findings collaborates with the study of Singh et al (2014) who evaluated the genotypic variation among 5 rice genotypes at 4 nitrogen availability in relations to grain yield, biological yield, panicle weight, primary and secondary branch, and recorded significant correlation between nitrogen doses and above discussed traits. Also, Rahman et al, (2004) on their paper, "response of photosensitive rice to nitrogen levels in boro season" reported variation in plant height for rice variety at variable N doses.…”

Diazotrophic Endophytes of Poplar and Willow for Growth Promotion of Rice Plants in Nitrogen‐Limited Conditions

“…Many improved and hybrid rice varieties require comparatively large amounts of N to achieve maximum grain yield. In many rice-growing countries, more than 100 kg N ha −1 is applied to rice cultivation (Huang et al, 2008;Wang et al, 2012;Roberts et al, 2013;Singh et al, 2014). However, only a small proportion of the applied N is actually utilized by the crop plants, with a significant portion lost to the environment through denitrification, leaching, and ammonia volatilization (Cassman et al, 2002;Choudhury and Kennedy, 2005).…”

Influence of 34-years of fertilization on bacterial communities in an intensively cultivated black soil in northeast China

“…Li et al, 2014). Over the past 100 years, extensive agricultural intensification has been implemented by high inputs of chemical fertilizers which, in turn, are resulting in serious degradation of soil physicochemical properties (Singh et al, 2014). The nutrient-based alteration and associated microbiota were not surprisingly reflected in significant shifts in nitrogen-fixing bacteria (Berthrong et al, 2014), ammonia-oxidizing bacteria (Ai et al, 2013), methanotrophs (Dai et al, 2013) and denitrifiers (Tang et al, 2010).…”