Numerous studies show that nitrogen deficiency is a major constraint to increasing yield in rice plants. Therefore, maintaining nitrogen levels is essential for guaranteeing yield when growing rice. Nitrogen deficiency is indicated by changes in the intensity of the green of the leaves, from intense green to yellowish hues indicative of severe deficiency. The colour comparison table shows hues from yellowish-green to dark green, for matching the range of colours found in rice leaves.
The aim is to keep the leaves within the critical range shown in the table in order to obtain optimum growth. Deviation from the optimum colour is corrected by nitrogen application until the optimum colour is restored. It should be taken into account that the colour of rice leaves with more or less nitrogen will depend to a large extent on the variety, climate, crop density, etc. Therefore colour comparison tables are being developed that take all these variables into account and adjust the colours according to the characteristics of each area.
More than 250,000 4-panel colour comparison tables have been distributed since the start of the programme in 2003 to rice growers in rice-producing countries such as Bangladesh, India, Indonesia, the Philippines, Thailand and Vietnam.
For more information on this technique, a PDF is attached giving further information about the colour comparison table: “Tabla de comparación de colores para el manejo efectivo del nitrógeno del arroz”.- C.Witt, J.M.C.A Pasuquin, R.Mutters and R.J. Buresh. (Colour comparison table for effective nitrogen management in rice).
Useful links for rice growing:
GUIDE FOR IDENTIFYING LIMITATIONS IN THE FIELD FOR RICE PRODUCTION (http://www.fao.org/docrep/006/y2778s/y2778s00.HTM)
INTERNATIONAL RICE RESEARCH INSTITUTE
IPNI INTERNATIONAL PLANT NUTRITION INSTITUTE
“Arroz: desórdenes nutricionales y manejo de nutrientes” (Rice: nutritional disorders and nutrient management).