Using SPAD-502 to evaluate the total chlorophyll and nitrogen status in leaves of longkong (Aglaia dookkoo Griff.) and rambutan (Nephelium lappaseum L.)

Total chlorophyll and nitrogen status in leaves of longkong and rambutan were evaluated by using the SPAD-502 meter. Leaves of both species were sampled from 10 year-old trees grown in an experimental plot at Prince of Songkla University, Hat Yai campus. The relationship between SPAD-502 meter reading (SPAD) and total chlorophyll content analyzed in the laboratory was evaluated in longkong and rambutan, and they were y = -2.68+0.21x, R*[2) = 0.77 and y = -1.11+0.18x, r*[2) = 0.77, respectively. The data recorded by SPAD were also linearly related in a positive manner to nitrogen status in longkong (y = 1.27+0.20x, r*[2) = 0.82) and rambutan (y = 1.17+0.02x, r*[2) = 0.79). The results show that using the SPAD-502 meter is convenient and fast for the evaluation of total chlorophyll and nitrogen status in leaves of longkong and rambutan.