Nitrogen Uptake and Translocation in Vanda Orchid after Roots and Leaves Application of Different Forms 15N Tracer

Vanda is an economically important orchid that widely produced in Thailand. Usually, growers apply large amounts of fertilizer throughout the plant, covering leaves and roots to ensure good quality products. Nitrogen fertilizer, terms ammonium (NH4+) nitrate (NO3−), generally used as N source. In addition, nitrogen organic (glutamine) increasingly being promote rapid growth some plants. However, absorption efficiency compared with inorganic form (NH4+ NO3−) via or has not been evaluated. Therefore, this research aimed compare fate (in glutamine form) using a 15N tracer. ‘Patchara Delight’ was grown plastic greenhouse under 50% shading net at average temperature 25 °C 80% relative humidity (RH). The plants were sprayed weekly 100 mL solution, 2.5 mM 15NO3− + NH4+ (N1), NO3− 15NH4+ (N2), (15N2)(N3) for 4 weeks. then sampled separated into roots, abundance analyzed elemental analyzer coupled isotope-ratio mass spectrometer IRMS. received only showed highest use (15NUE) about 28.19% 30 days after first feeding (DAF), whereas resulted lowest 15NUE among sources. Regardless application site, supplied lower labeled concentration content stems than those fed combination sole 15N-glutamine. largest concentrations stems, found roots. At DAF, solution either combined solitary 15N-glutamine did affect leaves. supplying can provide 4–7% higher NUE N, especially when