Nitrogen fertilizer rate based on Leaf Color Chart (LCC)for some rice varieties

Plant based tools for real time nitrogen management in rice through use of Leaf Color Chart (LCC) is becoming increasingly popular with South and south East Asian rice farming. A study was conducted to determine the effect of 4 levels each of nitrogen fertilizer and a control without N fertilizer on three plant types i.e. Hybrid (Deilam); improved variety: 'Khazar' (dark green leaf); traditional landrace: 'Hashemi' (light green leaf) in 2008 and 2009 at the Rice Research institute of Iran (RRII) farm, Rasht in a split plot based on RCB design with three replications. Grain yield (t/ha), plant height (cm), tiller number, days to maturity, no. of filled grains and 1000 grain weight (g) were recorded. Total N uptake (kg N/ha), recovery efficiency (RE) (%) and agronomic efficiency (AE) (kg grain/kg N applied) were derived at the end of the experiment. ANOVA results clearly showed significant differences between treatments in both the years. As expected the three plant types differed significantly (at P=0.01) for all the traits studied. Analysis for revealed the N management treatments were significantly different for grain yield, plant height, tiller number, days to maturity, no. of filled grains and total N uptake (at P=0.01) while significant (at P=0.05) for recovery efficiency (RE). Two way interaction between the plant types and N management treatments were highly significant (at P=0.01) for grain yield, total N uptake, recovery efficiency and agronomic efficiency. Compaision means for yield showed that recorded 6681, 6128 and 4626 kg/ha for Hybrid, Khazar and Hashemi varieties respectively. Nitrogen Use Efficiency (NUE) table showed that 2th treatment (20 kgN/ha) in all of characters was above than other treatments, such as RE (72.4%), AE (36.21 kgG/kgN) and PE (32.54%) with used 70 kgN/ha. At presently, all naturally light green traditional varieties like Hashemi the critical shade of LCC was determined as 3 while for dark green improved varieties like Khazar and hybrid (Deilam) as 4. If you find five leaves or more out of 10 randomized leaf samples for LCC reading were less than the critical shade number then a top dressing of 20 kg N/ha (i.e.45kg of Urea) for tall traditional varieties (like Hashemi) and 30 kg N/ha (65kg of Urea) for improved (Khazar) and hybrid (Deilam) rice varieties respectively.