Nutrient deficiency diagnosis in tectona grandis

Abstract

The foliar nutrient concentration of ten year old Teak plants collected from the Nilambur Teak plantation were analysed to standardize the canopy height, time of sampling, leaf rank and diameter class during the period 1992 – 94. Also, the leaf samples from the standardised position and time interval were analysed for a period of thirteen months starting from August, 1993 to August 1994 to study the variation in the foliar N, P and K concentration with season. Further, leaf samples from four different site qualities viz., site quality 1, 11,111 and 1V were analysed to determine the critical nutrient level. The chemical analysis of the leaf samples were carried out in the College of Forestry, Kerala Agricultural university, Vellanikkara. Since mean nutrient concentration was high and varied little among the samples, leaves taken from the bottom position of the crown during the time interval 9.am. to 11 a.m. were taken as the standard. Similarly, the second leaf rank from the tip and the fourth diameter class which was the largest, (16.75 cm – 20 cm) were found to be ideal for sampling. The foliar nutrient concentration were higher during the period starting from June to September, which received high rainfall and were low during the drier months of January, February, March and April. Equations were developed to predict the yield based on foliar nutrient concentration. A simple linear model of the form Y = B * X + A was used to predict the yield in terms of basal area or volume and the foliar nutrient concentration; where Y = basal area (m2) or volume (m3), X = foliar nutrient concentration and A and B are constants. But a higher predictability was obtained for the relationship between basal area or volume and foliar nitrogen, phosphorus and potassium concentration, when fitted with super geometrical model, Couchy model and parabolic model respectively. The super geometrical model used for the relationship between basal area or volume and foliar nitrogen concentration was of the form