The Uptake, Partitioning, and Uses of Nitrogen in Phalaenopsis Sogo Yukidian ‘V3’
Date Issued
2008
Date
2008
Author(s)
Peng, Ying-Chun
Abstract
In order to realize the demand of nitrogen form ratio during the vegetative and reproductive growth stages in Phalaenopsis Sogo Yukidian ‘V3’, five fertilizers with different nitrogen form ratio (NH4+: NO3- = 0:100, 25:75, 50:50, 75:25, 100:0) were applied to 8.5-cm and 10.5-cm pots for two flowering cycles. The days to spiking, visible buds, and anthesis were not affected by nitrogen from ratio during two flowering cycles. However, the number of flowers, the diameter and length of stalk in the second flowering cycle were decreased when plant received more than 50% NH4+-N. The fresh weight, leaf number and area decreased with the increase of NH4+-N ratio. When plants were provided with 50% or higher ratio of NH4+-N, the absorption of cations by roots was inhibited, the concentrations of calcium and magnesium in Phalaenopsis decreased, and the symptom of ammonium toxicity occurred, such as growth retardation, chlorosis leaves, and necrotic roots. It is recommended to provide Phalaenopsis with 75% nitrate and 25% ammonium nitrogen in order to have the highest percentage of spiking, fresh weight, and leaf numbersn order to understand the uptake and partitioning of nitrogen, the roles of organs in sink and source relationship during different stages, and the nitrogen sources of stalks in Phalaenopsis, the isotopic nitrogen (15N) was used as a tracer. Isotopic nitrogen was applied to Phalaenopsis Sogo Yukidian ‘V3’ during the vegetative or reproductive growth stage, in a nutrition deficiency or abundance situation, and different parts of plants. Both leaves and roots were able to utilize nitrogen, and the absorbed nitrogen was distributed to two major sinks: newly grown leaves and newly grown roots. Nitrogen uptake efficiency was highest in new roots, lower in old roots, and lowest in leaves. No difference of nitrogen uptake efficiency was found in the upper or lower epidermis of leaves. The absorption of nitrogen did not differ between the vegetative and reproductive growth stages, and the partitioning of nitrogen depended on the sink strength. During the vegetative growth stage, newly grown leaves were the major sinks. Strength of sink decreased with the increase of leaf age. Stalk was the major sink during the reproductive growth stage. For the nitrogen demand of stalks from spiking to visible buds stage, 29% were provided from the nitrogen previously stored, and 71% from the recent fertilizer applications. Mature leaves and roots were the major sources where nitrogen stored. However, the percentage of nitrogen supply from these two organs depended on the nutrition situation of plants.n summary, mature leaves and roots had the functions of nitrogen store and supply, therefore, a short-term nutrient deficiency did not retard the growth of Phalaenopsis. However, a deficient or improper nutrition level for a long period reduced plant growth and flowering quality. Providing fertilizer with the ratio of 75% nitrate and 25% ammonium nitrogen throughout the vegetative and reproductive growth stages to Phalaenopsis will result in the best product quality.
Subjects
Phaleanopsis
Nitrogen
Isotope
SDGs
Type
thesis
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