Guttation fluid as a physiological marker for selection of nitrogen efficient rice (Oryza sativa L.) genotypes

A field experiment was conducted during the rainy season of 2008 and 2009 to use guttation fluid as a physiological marker for the screening of more nitrogen efficient rice genotypes on the basis of relationship between Guttation Fluid (GF) oozed by leaf tip and nitrogen use efficiency (NUE), grain yield (GY) and biological yield (BY) amongst five rice (KRH-2- hybrid, Kasturi- aromatic, Krishna Hamsa, Tulsi and Vasumati- high yielding) genotypes grown at four nitrogen levels (0, 50, 100 and 200 kg ha-1) in alluvial soil of Pantnagar (Uttarakhand), India. The nitrogen fertilizer (urea) was sprouted in the field. For this experiment, the field was made to keep with 5 cm standing water throughout active tillering and reproductive stage. Guttation fluid (GF) was collected during flowering stage whilst other traits after harvesting of the crops. The utmost and lowest GF was achieved by genotype KRH-2 and Kasturi respectably. All the rice genotypes showed the positive correlation between GF and NUE, GY, BY at different nitrogen levels vice-versa. The KRH-2 illustrated better response to secretion of guttation fluid and other traits. The experiment concluded that the amount of GF is directly associated with application of fertilizer as well as NUE, GY and BY. Further studies are good opportunities for rice researcher to improve rice yield through this way and mapping the genes controlling this trait and creating rice plant with increase guttation fluid at different nitrogen levels for selection of high nitrogen efficient rice genotypes.   Key words: Biological yield, guttation fluid, nitrogen use efficiency, grain yield, rice genotypes.