Standardization of Leaf Color Chart (LCC) on rice varieties and hybrids for efficient N use.

Plant based tools for real time nitrogen management in rice through use of chlorophyll meter or Soil Plant Analysis Development (SPAD) meter and 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 two levels each of LCC and SPAD meter as compared with recommended dose of nitrogen (80 kg N) and a control without any N fertilizer on three different plant types i.e. hybrid: IRH1improved variety: 'Khazar' (dark green leaf)traditional landrace: 'Hashemi' (light green leaf) at the Rice Research institute of Iran (RRII) farm, Rasht over two years (2005-2006) in a split plot based on RCB design with three replications. The three different plant types were taken as main plots while the different N tools and levels i.e. LCC3, LCC4, SPAD 35 and SPAD 38 with recommended fertilizer and control (without any fertilizer) treatments as subplots. Twenty day old seedlings were transplanted in experimental plots that received basal application of 60kg/ha P and 60kg/ha K fertilizer uniformly. 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. Combined analysis for both years 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. LCC4 had RE of 59 % that was significantly higher as compared with recommended N practice with RE of 42 %. LCC3 and LCC4 readings reflected the SPAD 35 and SPAD 38 respectively as expected over the three plant types especially for grain yield and total N uptake. Hybrid rice 'IRH1' and improved variety 'Khazar' showed LCC4 and SPAD 38 are the best N management practices based on grain yield with relative yield advantage of 27 % over recommended N practice respectively. However, for tall and light green colored leaf cultivar such as 'Hashemi' a LCC 3 and SPAD 35 reading gave no grain yield advantage over recommended N practice but saved on nitrogen fertilizer. The widely grown 'Hashemi' landrace had less incidence of blast and reduced plant height under LCC3 as compared to LCC4 or recommended N practice. At presently, we are promoting the wide scale adoption of LCC as N management tool by training the farmers and freely distributing them Persian translated LCC tool and pamphlets.