Determination of Nitrogen Fertilizer Requirment in Rice Based on Leaf Color Chart

Synchronizing of nitrogen fertilizer application with the timing when plant needs nitrogen can increase nitrogen fertilizer efficiency and grain yield in rice. This timing can be determined by tools such as Leaf Color Chart (LCC) and Soil Plant Analysis Development (SPAD). This study was conducted to determine the nitrogen fertilizer requirement rates for rice varieties based on color number by LCC tool. This experiment was conducted as split plot arrangements in randomized complete block design with three replications for two years (2008 and 2009) at the Rice Research Institute of Iran (RRII) experimental field, Rasht, Iran. Experimental factors were rice varieties at three levels (Deylam, Khazar and Hashemi) as main plot and five levels of nitrogen (recommended, 20, 30, 40 and 50 KgNha-1) assigned to sub plots. Results showed significant (P<0.01) differences between rice varieties for plant height, no. of unfilled grains and 1000 grain weight. Rice varieties differed significantly (P<0.05) for grain yield, tiller number and number of filled grains. Rice varieties also differed significantly (P<0.05) for nitrogen use rate. Variety × nitrogen interaction was significant on plant height, length of panicl and grain yield. Grain yield of Deylam, Khazar and Hashemi varieties were 6681, 6128 and 4626 Kg ha-1, respectvely. Result also showed that use of 20 Kg ha-1 increased recovery efficiency (72.41%) and agronomic efficiency (36.21 Kg Kg-1). In conclusion, for Deylam and Khazar varieties 30 Kg ha-1 of nitrogen (65 Kg urea ha-1) and for Hashemi variety 20 Kg ha-1 of nitrogen (45 Kg urea ha-1) is recommended.