Abstract:
Sand culture studies were conducted in College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur with an objective of inducing the symptoms of deficiency of various nutrient elements in seedlings of teak (Tectona grandis Linn.f.) grown in sand culture. The effects of nutrients viz., N,P,K, Mg,S,Zn and Mo on the growth, chlorophyll content and nutrient concentration of seedlings in the nursery were also studied. The results were finally confirmed by recovery studies by supplying the seedlings showing the symptoms of deficiency of various elements with complete nutrient solution. For the study, two months old seedlings of uniform growth were planted in containers filled with pure quartz sand and supplied with Hoagland No. 2 (1948) nutrient solution. The treatment solution was prepared by eliminating the desired nutrient from the complete Hoagland nutrient solution.
The characteristic deficiency symptoms produced by seedlings due to the deficiency of various nutrient elements include leaf discolouration, necrosis, scorching, defoliation and growth stunting. The seedlings showing visual deficiency symptoms were also photographed. Seedlings that received complete nutrient solution were healthy with dark green foliage. Vegetative growth of the seedlings was also found to be affected due to the nutrient stress. All the fractions of chlorophyll ie; chlorophyll – A, chlorophyll – B total chlorophyll of the treatment seedlings particularly N deficient seedlings declined considerably during the study period. Visual deficiency symptoms of the nutrient elements also coincided with a corresponding reduction in foliar levels of the cocernrt element. There was remarkable improvement in the growth and recovery of the visual symptoms when the deficient element was again supplied to the seedlings through complete nutrient solution. The foliar nutrient content of these seedlings was also found to be improved significantly on application of complete nutrient solution.
