Abstract:
Sand culture experiments were carried out under controlled conditions inside a glasshouse attached to College of Horticulture, Kerala Agricultural University main campus, Vellanikkara, during the period 1991-93 for inducing deficiency symptoms of various nutrient elements in the seedlings of Ailanthus (Ailanthus triphysa (Dennst.) Alston). The effects of major nutrients viz., N, P, K Mg and S on the growth, chlorophyll content and nutrient concentration of seedlings in the nursery were also studied. The results were also 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 i.e., chlorophyll – A, chlorophyll – B and total chlorophyll of the treatment seedlings declined during the study period compared to control. Visual deficiency symptoms of the nutrient elements also coincided with a corresponding reduction in foliar levels of the concerned element. There was remarkable improvement in the growth and recovery of visual symptoms when the deficient element concerned was again supplied to the seedlings through complete nutrient solution.
