Identifying N sources that afect N uptake and assimilation in Vanda hybrid using 15N tracers
2018
Kanokwan Panjama, Chiang Mai University, Chiang Mai, Thailand | Takuji Ohyama, Niigata University, Niigata, Japan | Norikuni Ohtake, Niigata University, Niigata, Japan | Takashi Sato, Akita Prefectural University, Akita, Japan | Nuttha Potapohn, Chiang Mai University, Chiang Mai, Thailand | Kuni Sueyoshi, Niigata University, Niigata, Japan | Soraya Ruamrungsri, Chiang Mai University, Chiang Mai, Thailand
Vanda is an aerial tropical orchid native to Thailand and nitrogen (N) fertilizer is mainly used to promote its growth and quality. However, little is known about the characteristics of N absorption and assimilation in Vanda. The objective of this study was to determine the appropriate source of N for Vanda cultivation. In this experiment, shoots and roots of Vanda 'Ratchaburi Fuchs-Katsura' were sprayed weekly with 100 ml of 15N tracer solution (1) 10 mM of 15NO3 −, (2) 5 mM of 15NO3 − plus 5 mM of NH4 +, (3) 5 mM of NO3 − plus 5 mM of 15NH4 + and (4) 10 mM of 15NH4 +. The results indicated that plants fed with a combined N fertilizer gave the highest of 15N use efciency (15NUE) of about 21.8%, 30 days after the frst feeding (DAF), compared with those fed sole sources of 15NO3 − (21.0%) and 15NH4 + (16.6%). However, a sole nitrate fertilizer or combination fertilizer did not signifcantly afect the total N and labelled N content. Alanine was a major amino acid found in leaves and roots at 7 DAF, whereas glutamine was mainly found in stems. At 30 DAF, tyrosine and alanine became major components in the leaves, and glutamine decreased in stems when plants were fed with a single 15NH4 +source.
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