Dris-based nutrient norms for Nagpur mandarin (Citrus reticulata)*

Abstract

The DRIS norms computed from the data from the set of 57 irrigated commercial 'Nagpur' mandarin (Citrus Jambhiri Lush.) orchards representing 26 locations and 3 basalt derived soil orders (Entisols, Inceptisols and Vertisols) rich in smectite minerals suggested optimum leaf macronutrient concentration (%) as 1.70-2.81N, 0.09-0.15 P, 1.02-2.59K. 1.80-3.25 Ca, and 0.43-0.92 Mg. While optimum level of micronutrients (ppm) was determined as 74.9-1 13.4 Fe, 54.8--84.6 Mn, 9.8- 17.6 Cu, and 13.6-29.6 Zn in relation to fixit yield of 47.7- 117.2 kg/tree. Primary DRIS indices developed on the basis of leaf analysis revealed deficiency of N, P, K, Fe and Za. The nutrient constraints so diagnosed were observed to improve fruit yield in a progressive nutrient response experiment.