Diagnosis of nutrient imbalance in mango by DRIS and PCA approaches.
Raghupathi H. B., Reddy Y. T. N., Reju M. K., Bhargava B. S.
Author Affiliation: Indian Institute of Horticultural Research, Hessaraghatta, Bangalore, India.
Journal of Plant Nutrition 27 : 1131-1148
Abstract : The effect on the nutrient concentration in Totapuri cultivar of mango leaf of varying levels of nitrogen (N at 0, 10, 25, 50, 100, 150, 200 and 400 g/plant per year), phosphorus (P at 0, 5, 10, 20, 50 and 100 g/plant per year), or potassium (K at 0, 10, 20, 30, 100 and 200 g/plant per year) was monitored in three field experiments for a period of nine years (1991-99) in Bangalore, Karnataka, India. A data bank of nutrient concentration vs. fruit yield was established based on the mean nutrient concentration determined for the different treatments. The data was further sub-divided into low and high yielding population based on yield performance. The Diagnosis and Recommendation Integrated System (DRIS) ratio norms were developed from high yielding population, while the diagnosis of nutrient imbalance was made in low yielding plants. Forty-five nutrient expressions were chosen as diagnostic norms. Fruit yield was low in four to five cropping seasons. DRIS indices showed no signs of improvement nor was there a trend with the application of N, P, or K at different levels. Some measures of total imbalance of nutrients in plant were reflected through sum of DRIS indices irrespective of the sign. The high imbalance of nutrients resulted in lower fruit yield. Principal Component Analysis (PCA) was applied to extract the correlation structure among the nutrient in low and high yielding plants and for DRIS indices. The first PC derived by PCA performed both on absolute nutrient concentration and DRIS indices was designated as (N - P + Mg - S + Fe + Cu +). Involvement of several nutrients in a single PC indicated that it was not possible to diagnose nutrient imbalance of any particular nutrient in isolation in fruit crops like mango. The nutrient concentration variation in mango leaf appears to be an overall orchard phenomenon rather than individual tree phenomenon.