Orchid in vitro growth as affected by nitrogen levels in the culture medium

Abstract

In vitro cultivation is the main propagation method for the family Orchidaceae, whereas nitrogen is the most important nutrient in the culture media. This work was carried out to study the influence of different nitrogen concentrations on the in vitro growth of the orchid Phalaenopsis amabilis. Nitrogen concentrations varied by altering the ionic balance of the Murashige & Skoog (MS) culture medium. Plants, 360 days old, were cultivated in liquid MS, modified with 7.5, 15, 30, 45, and 60 mM N. After 180 days, we assessed plant and root length, number of leaves and roots, and fresh and dry weight of leaves, roots and plants. Treatments were assigned to completely randomized plots, with four replications. Plots consisted of five three-plant flasks. The lowest nitrogen level (7.5 mM) in the medium induced root development in length, number, and fresh and dry weight. The concentration 30 mM N stimulated both emission and dry weight accumulation of leaves. The original nitrogen concentration in the MS medium (60 mM) was excessive for the in vitro growth of P. amabilis.

Effect of <i>In Vitro</i> Nitrogen Nutrition to <i>Phalaenopsis deliciosa</i> Seedling Growth

“…In addition, we observed maximum seedling yield at 1× macronutrient level, or 14.2 mM or 200 ppm of N. This result was contradicting with work on P. amabilis and Phalaenopsis hybrid, where maximum yield was observed at 7.5 mM (Tavares et al, 2012) or 100 ppm (Poole and Seeley, 1978) of N respectively. This could be due to the higher amount of phosphorus in the media used in this study, which was 5.9 mM or 180 ppm compared to 1.25 mM (Tavares et al, 2012) and 20 ppm (Poole and Seeley, 1978) in other studies.…”

“…In contrast, theoretically, increase of N will increase yield until it reaches asymptote where further increase of N will not increase yield anymore (Lawlor, 2002). Similarly to Tavares et al (2012), our results did not exactly fit the N response curve probably because of another factor at work, the genetic factor, since all the plants used for the study were of different genotypes raised from different seeds.…”

“…This was different with the approach used by other authors (Tavares et al, 2012;Poole and Seeley, 1978) where only nitrogen was altered but other macronutrients were not. This experiment was done with the assumption that nutrient balance could be another factor contributing to the differences observed, especially for important nutrient such as N. For example, fertilizers are normally applied in N:P:K ratio.…”

“…The effect of macronutrient level to orchid development was similar to response of P. amabilis to N, a species in the same subgenus as P. deliciosa (Christenson, 2001), where R/S ratio was found to reduce with N concentration (Tavares et al, 2012). In addition, we observed maximum seedling yield at 1× macronutrient level, or 14.2 mM or 200 ppm of N. This result was contradicting with work on P. amabilis and Phalaenopsis hybrid, where maximum yield was observed at 7.5 mM (Tavares et al, 2012) or 100 ppm (Poole and Seeley, 1978) of N respectively. This could be due to the higher amount of phosphorus in the media used in this study, which was 5.9 mM or 180 ppm compared to 1.25 mM (Tavares et al, 2012) and 20 ppm (Poole and Seeley, 1978) in other studies.…”

Initial in vitro Establishment of the Native Cerrado Orchid Miltonia Flavescens

“…The nitrate concentration in relation to the ammonium is higher in these media, which in turn benefited the rooting. The harmful effect of ammonium on root formation was also reported by Tavares et al (2012) in Phalaenopsis amabilis plants cultivated for one year in different nitrate and ammonium concentrations.…”