Effect of nitrogen on whole plant carbon gain and nitrogen use efficiency in Cedrus deodara and Cupressus torrulosa Masoodi N. A., Masoodi T. H., Gangoo S. A., Islam A. Department of Forestry, Faculty of Agriculture, S.K. University of Agricultural Sciences and Technology of Kashmir, Wadoora, Sopore, (J&K)-193 201 Abstract Carbon gain, relative growth rate, biomass allocation, nitrogen uptake efficiency and nitrogen use efficiency were determined in Cedrus deodara and Cupressus torrulosa seedlings after 24 weeks growth in nursery under varying levels of nitrogen additions in Forest nursery at FOA, Wadoora, following pretreatment with ingested complete nutrient solution for 4 weeks in mist chamber. Seedlings were fertilized twice in a week with 2, 3, 4, 5, 6, 7, 8 and 9 mg of nitrogen seedling−1 after pretreatment. Both the species recorded more than 55% increase in height, and 25–36% in root collar diameter at highest N addition rate as compared to the control. Total biomass increased by 40 and 43% in C. deodara and Cupressus, respectively, against the control at 9 mg addition. Cedrus deodara seedlings grew fast at 8 mg nitrogen addition rate but RGR was higher in C. torrulosa at lower N rates. Nitrogen uptake efficiency increased in both species with increase in N addition but with significant decrease in nitrogen use efficiency. C. deodara was more efficient than Cupressus in N uptake and succeeded in taking up 61.8% N at highest addition rate. Cupressus was also effective in N uptake could capture only 50.3% of the N added at this rate. Biomass allocation and N concentration in different parts of seedlings varied significantly with treatments in both the species. Low N resulted in smaller seedling size but relatively more biomass was allocated to roots than under high N conditions in C. deodara. Allocation to roots increased at higher addition rates. Nitrogen stress generally favoured biomass allocation to roots at the expense of needles and stem. The seedling N concentration generally declined with time especially at lower addition rates. Top Key words Cedrus, Cupressus, relative growth rate, nitrogen use efficiency, nitrogen uptake efficiency. Top |