Leaf colour chart for nitrogen management in rice – A review
Abstract
Leaf Colour Chart (LCC) has substituted chlorophyll meter (SPAD) to estimate the leaf nitrogen (N) status of rice (Oryza sativa L.) and for timely N fertilizer application. It is an inexpensive, simple and easy to use tool with six shades of greenness from light yellow to dark green. LCC readings are taken once in a week, starting from 14 days after transplanting for transplanted rice and 21 days after seeding for wet seeded rice. Readings aretaken once every 7 – 20 days until the first flowering. The critical value is 3 for varieties with light green foliage and 4 for all other varieties and hybrids. If the critical value of the leaf falls below the threshold value, 35 kg N/ha during kar/kuruvai/navarai and 30 kg N/ha during samba/thaladi/pishanam season need to be applied. As nitrogen supply matches with the crop demand, there is considerable yield increase under LCC - N management and because of the optimum N supply, there is saving of nitrogenous fertilizers to the tune of 20 – 40 kg/ha.
