Main Article Content
Estimation of chlorophyll and nitrogen levels in aromatic coconut leaves by chlorophyll meter (Minolta SPAD-502), extracting nitrogen concentrate in leaves, and the absorption range of chlorophyll obtained from UV-VIS spectrophotometer were performed in this research. A relationship between the amount of chlorophyll in the leaves, green leaf value, and the concentration of nitrogen in the leaves was established. The experiment was conducted at a farmer field in Ko-Taeo subdistrict, Mueang district, Songkhla province, by randomized complete block design with 5 replications. There are 4 treatments providing different Long Ashton nutrient solution nutrients with different nitrogen levels. It was found that the dynamic values of the leaf greenness index measured from the SPAD chlorophyll meter reading (SCMR), the concentration of leaf nitrogen and the absorption range of chlorophyll, are associated with the development of the leaf phase. It shows that the ages and the location of the leaves are related to the greenness and nitrogen content. In addition, it was found that the leaf greenness values increased significantly in accordance with the rate of nutrient solution with increased nitrogen. The results showed a linear relationship between leaf greenness index, nitrogen concentration and chlorophyll content. The results indicated that leaf greenness could be used as an indicator for evaluating the concentration of nitrogen and chlorophyll in the leaves. Therefore, this research can guide farmers to manage the suitable nutrient solution in aromatic coconuts.
 Krisnaphuk, K., 2014, Thai Coconuts Attractive New Alternative, Thailand Research Fund, Bangkok, 28 p. (in Thai)
 Saradhuldhat, P., Choorueng, M., Abdullakasim, S. and Phavaphutanon. L. 2014, Macro-nutrient content in aromatic coconut produced, Khon Kaen Agric. J. 42(3): 192-197. (in Thai)
 Department of Agricultural Extension, 2012, Report of the Crop Production Situation Year 2012, Available Source: http://production.doae.go.th/report/report_main2.php?report_type=2, March 9, 2019. (in Thai)
 Jayasekara, K.S., Jayasekara, C. and Periya thamby, S., 1991, Report of the Soils and Plant Nutrient Division, Annual Report of Coconut Research Institute, Lunuwila.
 Hewitt, E.J., 1966, Sand and Water Culture Methods Used in the Study of Plant Nutrition, 2nd Ed., Commonwealth Agricul tural Bureau, Farnham Royal, Bucks.
 SAS Institute, Inc., 1989, SAS/STAT User’s Guide, 4th Ed., Cary, NC.
 Li, Y.C., Alva, A.K., Calvert, D.W. and Zhang, M., 1998, A rapid nondestructive technique to predict leaf nitrogen status of grapefruit tree with various nitrogen fertilization practices, HortTechnology, 8: 81-86.
 Kaewkong, P. and Sdoodee, S., 2005, Evaluation of nitrogen status and total chlorophyll in longkong (Aglaia dookkoo Griff.) leaves under water stress using a chlorophyll meter, Songklanakarin J. Sci. Technol. 27(4): 731-741. (in Thai)
 Chanaweerawan, S. and Sdoodee, S., 2002, Using SPAD-502 to evaluate the total chlorophyll and nitrogen status in leaves of longkong (Aglaia dookkoo Griff.) and rambutan (Nephelium lappaseum L.), Songklanakarin J. Sci. Technol. 24(1): 9-14. (in Thai)
 Sritontip, C., Khaosumain, Y. and Changjeraja, S., 2011, Influence of various nitrogen on chlorophyll content and leaf nitrogen in Longan, J. Agric. Res. Extension 28(2): 19-24. (in Thai)
 Chiarawipa, R. and Sirikantayakul, C., 2015, Phenotypic plasticity in Robusta coffee trees in a mixed orchard system, Agric. Sci. J. 46(3)(Suppl.): 433-436. (in Thai)
 Yang, H., Li, J., Yang, J., Wang, H., Zou, J. and He, H., 2014, Effects of nitrogen application rate and leaf age on the distribution pattern of leaf SPAD readings in the rice canopy, PLoS ONE 9(2): e88421.
 Peng, S., Garcia, F.C., Laza, R.C. and Cassman, K.G. 1993. Adjustment for specific leaf weight improves chlorophyll meter’s estimation of rice leaf nitrogen concentration. Agron J. 85: 987-990.
 Shukla, A.K., Ladha, J.K., Singh, V.K., Dwivedi, B.S., Balasubramanian, V. and Gupta, R.K., 2004, Calibrating the leaf color chart for nitrogen management in different genotypes of rice and wheat in a systems perspective, Agron J. 96: 1606-1621.
 Lemaire, G., Jeuffroy, M.H. and Gastal, F., 2008, Diagnosis tool for plant and crop N status in vegetative stage: Theory and practices for crop N management, Eur. J. Agron. 28: 14-624.
 Prost, L. and Jeuffroy, M.H., 2007, Replacing the nitrogen nutrition index by the chlorophyll meter to assess wheat N status, Agron. Sustain. Dev. 27: 321-330.
 Giletto, C.M. and Echeverría, H.E., 2013, Chlorophyll meter for the evaluation of potato N status, Am. J. Potato Res. 90: 313-323.
 Kawakami, E.M., Oosterhuis, D.M., Snider, J.L. and FitzSimons, T.R., 2013, High temperature and the ethylene antagonist 1-methylcyclopropene alter ethylene evolution patterns, antioxidant responses, and boll growth in Gossypium hirsutum, Am. J. Plant Sci. 4: 1400-1408.
 Vongsubun, S., Krisanapook, K. and Phava phutanon, L., 2012, Estimation of chlorophyll and nitrogen levels in Pummelo leaves by chlorophyll meter, J. Sci. Technol. 1(2): 40-50. (in Thai)