Jumpen Onthong, Piruth Tirapat, and Sasikarn Sukmee

pp. 287 - 296

Abstract

The standard concentration values are important for evaluation of plant nutrient status, classified into low, sufficient and high, which leads to the optimum nutrient management. However, the standard concentration values of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu) and boron (B) in longkong leaf (Aglaia dookkoo Griff.) have not been reported even though micronutrient deficiency symptom in some orchards was found. The objective of this research was to establish standard concentration values of Fe, Mn, Zn, Cu and B in longkong leaf. The leaf sampling was collected from middle leaflet of the 2^nd compound leaf (5-month-old leaf) at the post harvest stage during 2003-2005 from 7 orchards in Songkhla province and 3 orchards in Narathiwat province, 10 trees per orchard. Yield of individual tree was recorded and used for establishment of nutrient standard concentration values by the high-yield-tree method (>70 kg tree^-1) and the boundary-line method. The results revealed that the sufficient ranges of Fe, Mn, Zn, Cu and B established by high-yield-tree method were 74-88, 81-107, 16-19, 7-9 and 32-38 mg kg^-1, respectively and the sufficient ranges of Fe, Mn, Zn, Cu and B estimated by boundary-line method were 61-66, 49-58, 18-20, 7-8 and 27-30 mg kg^-1, respectively. The standard concentration values by the high-yield-tree method were higher than those of the boundary-line method. However, the values estimated by the boundary-line method, which was calculated from the linear regression of yield and individual nutrient, did not include nutrient luxury
consumption, and the values from this method can classify nutrients into deficient, low, sufficient and excess ranges. Therefore, the nutrient standard concentration values estimated by the boundary-line method should be used as the standard values for evaluation of Fe, Mn, Zn, Cu and B in longkong leaf.