THE EFFECT OF COCONUT FIBRE ON THE ROOTING OF BORDER PELARGONIUM (PELARGONIUM HORTORUM L. H. BAILEY) CUTTINGS

Małgorzata Zalewska, Anita Woźny

ABSTRACT

The studies estimated the effect of coconut fibre on the rooting of Pelargonium hortorum L.H. Bailey cuttings, ‘Präludium’ cultivar, at two dates – from 11 January to 8 February and from 14 February to 14 March, 2003. The cuttings were rooted in the medium consisting of high peat and perlite (4:1, v/v) and 15, 30 and 50% coconut substrate, respectively. The medium containing 30% of coconut fibre favoured the earlier formation of roots, at the same time increasing the mass of the root system, especially at the early date of rooting.

Key words: medium, coconut fibre, rooting of cuttings, Pelargonium hortorum..

INTRODUCTION

The greatest production and sale of pelargonium is observed on the German market, where more than 130 million plants were sold in 2000. According to the estimated data, the sale of pelargonium in Europe reaches 500 million, which shows a significant role of this species in flower production. In Poland, an intensive growth of pelargonium production began in the middle of the 1990’s, and it is increasing very fast [1].

The appearance of flowering plants, including pelargonium, is largely determined by a good quality of the cuttings, which is related for example to the nursery from where they are taken as well as to the conditions during the rooting period. Light, temperature, water, the type of the medium and its reaction as well as the gas composition of the atmosphere belong to those environmental factors that exert a significant influence on the process of forming adventitious roots in cuttings. They also determine a more or less positive effect of the growth substances applied during the rooting process [2]. Lack of any of these conditions makes the rooting process fail. The time of the rooting of cuttings is also important from the economic point of view.

The purpose of the present studies was to determine the usefulness of coconut fibre as an element of the medium for the rooting of border pelargonium cuttings (Pelargonium hortorum L. H. Bailey), ‘Präludium’ cultivar.

MATERIALS AND METHODS

The experiment was conducted at two dates: from 11 January to 8 February and from 14 February to 14 March, 2003. The study material consisted of border pelargonium (Pelargonium hortorum L. H. Bailey) cuttings, ‘Präludium’, one of the more valued cultivars used in wholesale production in Europe. It is a medium-early cultivar of very strong growth, with single, intensively red flowers, without any picture on the leaves.

The control combination – without coconut fibre – consisted of high light Baltic peat with the fraction of 0-7 mm, coming from Latvia, containing 0.4% of nitrogen, mixed with perlite in the volume proportion of 4:1, and additionally enriched with fertilizers PG-Mix (1.5 gˇdm^-3) and Osmocote Mini Star (1 gˇdm^-3). The other combinations contained a 15, 30 and 50% addition of coconut substrate, respectively. The coconut substrate containing 100% of coconut fibre (table 1) had been saturated with water a day before. According to the instruction, 7 litres of water should be used per 1 kg of substrate, in this way giving 12 l of the coconut substrate. pH value of the media of control combinations was established, like in the others, at the level of 5.0 – after mixing all components.

On 11 January, 2003, 640 pelargonium cuttings were planted, 160 in each combination, to multi-pot palettes with openings of 4 cm in diameter and 4 cm in height, filled with previously prepared media. Preparation Rhizopon AA 1% (containing IBA) was used for the rooting. The pots with cuttings were placed in a glasshouse equipped with an automatic system of controlling the climatic conditions of the cultivation.

In order to estimate the root system, 20 cuttings were taken from each combination (4 repetitions, 5 cuttings in each) eight times – every three and four days alternately. The roots were washed with water in order to wash off the remains of the medium, next, they were cut off the cuttings and their fresh mass was weighed. Then, the dynamics of the roots increase was estimated depending on the combination and date of the rooting of cuttings. In the case of the other date of rooting, the subsequent stages of the experiment proceeded like in the case of the first date. At each date, observations were performed for four weeks.

When a compact root clod that did not go to pieces was formed of the studied cuttings – which was connected with the combination of the medium and the applied date – the sample was subjected to valuation. The degree of overgrowth of the clod with the roots was estimated from the bottom to the side, using the scale of 1 to 3 (fig. 1).

In the period of rooting, the 24-hours’ temperature/relative humidity of the air in the glasshouse was kept at the level of 21.6°C/72.6% at the first date, and 21.3°C/72.8% at the other. The mean 24-hours’ temperature of the medium was 18.7°C – at both dates. The cuttings were additionally illuminated at night from 2.30 to 8.00 a.m. with sodium lamps of 400 W.

The significance of differences referring to the mean root mass was calculated by means of Tukey’s test.

RESULTS

At the first date of rooting, it was stated on the basis of the compact clod of the medium that the greatest number of cuttings with the best root system was isolated at the beginning of the third week in the combination with a 30% addition of coconut fibre. The combination with a 50% addition of coconut fibre turned out to be worse in the valuation, while the worst was the control (tab. 2, fig. 2).

After 28-days’ rooting, all cuttings – independently of the combination – formed compact root clods. The cuttings rooted in the subsoil with a 30% addition of coconut fibre had the most cuttings, with the best overgrown root clod. The combination with a 50% share of coconut fibre turned out a little worse, while the other medium did not have any cuttings that could be estimated the highest in the applied valuation scale.

At the second date of rooting – after 21 days – the root clod of all cuttings, regardless of the combination, was more or less overgrown with roots. The cuttings in the medium with a 50% addition of coconut fibre were best rooted. None of the rooted cuttings in the other media was estimated the highest considering the degree of overgrowth of the medium with roots (tab. 3, fig. 3). The cuttings in the medium with a 15% share of coconut fibre were best rooted.

Four weeks after the beginning of the cutting rooting in the medium with a 30% addition of coconut fibre were characterized by the best overgrown clod, those with 15% and 50% addition were worse, while the worst rooted were the cuttings from the control medium consisting only of peat and perlite.

The statistical analysis found out a significant influence of the medium composition and the date on the rooting of border pelargonium, ‘Präludium’ cultivar.

Independently of the date, the cuttings of pelargonium rooted in the medium with a 30% addition of coconut fibre had the biggest root mass after four weeks, in comparison with the plants of the other combinations (tab. 4).

At the first date the highest root mass was characteristic of the cuttings rooted with a 30% share of coconut fibre in the medium, in this way significantly differing from each of the other combinations. It can be stated on the basis of the estimation of the dynamics of the root mass increase that at the earlier date the cuttings rooted in the medium with a 30% addition of coconut fibre rooted the best throughout the period of studies (fig. 4).

The cuttings rooted without coconut fibre and with its 15% and 50% addition did not differ from each other in respect of the mass of the formed roots estimated at the end of the studies.

After the second date of cutting rooting, no differences in the root mass were noticed depending on the medium composition. The root mass increased in particular periods in similar ranges (fig. 5).

Regardless of the proportion of coconut fibre in the medium, the cuttings from the second date had a greater root mass. Only those that were rooted in the medium containing 30% of coconut fibre were an exception. In the case of this combination, the cuttings rooted both at the first and second dates reached a comparable mass of roots.

DISCUSSION

The rooting of cuttings is one of the more important stages the course of which determines the final condition of the produced plant. According to Chmiel [3], a mixture of garden earth, peat and sand is the most frequently used medium for the rooting of pelargonium cuttings. Chlebowski [4] also points to a positive effect of perlite, while according to Jerzy [5], a very good quality of the rot system as well as a shorter period of rooting are ensured using Protohumovit jointly with peat.

Nowadays, the traditional medium for plant rooting is successfully enriched with other components, for example superabsorbents, which have a positive effect on the cutting rooting of a lot of plants, including the decorative ones such as chrysanthemums [6], gerberas [7], carnations [8] and others belonging to border plants [9, 10]. Other studies also prove that success in the process of cutting rooting can depend on the addition of coconut fibre to the medium.

Good physical properties of coconut medium, and – first of all – high water and air volume as well as a stable structure are conducive to the rooting and the development of a big mass of bristles of rose cuttings [11]. The number of the roots formed is often reversely proportional to their length, and the effect of coconut fibre on this feature is often differentiated and related to the cultivar. According to Wiśniewska-Grzeszkiewicz and Rejman [12], the bedding of cover roses in the coconut medium mixed with high peat (1:1, v/v) has a positive effect on the number of rooted cuttings and the root length. Besides, a relation to the cultivar and the cutting date is also observed.

The authors’ own studies also point out that it is positive to supplement the standard medium, which is high peat mixed with perlite and coconut fibre during the rooting process. The medium containing 30% of coconut fibre had the best effect on the dynamics of the root increase and their mass, and hence on the final quality of the root system, which can suggest the possibility of shortening the process of cutting rooting, and – therefore – a precise economic effect. The final mass of roots formed by pelargonium cuttings was related not only to the proportion of coconut fibre in the medium but also to the date. The justification of a stronger effect of coconut fibre, with earlier rooting, seems to follow from the fact that the positive aspect of additional factors supporting this process is especially important and clear in the climatic conditions, especially of light, that are “more difficult” for plant rooting. After the period of light deficit, which took place in Poland till 15 February, the process of cutting rooting certainly takes place faster and better – even without the supporting factors.

Unpublished results of the authors’ own observations also point out that the cuttings of pelargonium, ‘Präludium’ cultivar, rooted in high peat with a 30% addition of coconut fibre, after being planted on the permanent places because of a greater root mass, start to grow and develop faster and better. The consecutive effect of the use of coconut fibre on the rooting is that the plants are bigger and flower more abundantly. The positive consecutive effect was also observed by Hetman and Szot [9] after adding hydrogels for the rooting of the pelargonium cuttings. Thanks to them, plants began to flower earlier and formed a greater number of inflorescences with a greater diameter.

This suggests the purposefulness of studying the effect of coconut fibre on other cultivars, not only due to their possible specific character, but also the consecutive effect of this element.

Noguera et al. [13] point out that the coconut media have a smaller water volume and contain less easily accessible water than sphagnum peats. Matysiak [14] explains the cause of weak rooting of cypresses and junipers by a smaller amount of easily accessible water and high salinity of uniform coconut media. According to her, coconut media can be used for the rooting of cuttings of potentially high natural ability to form adventitious roots.

High salinity of coconut media, which is the consequence of the big content of sodium, potassium and chlorine, being dependent for example on the place of obtaining the fibre or the technology of storing the waste makes it necessary to control the chemical parameters in particular groups of the imported fibre used for the preparation of proper medium for the cultivation of plants.

CONCLUSIONS

1. Independently of the date, the greatest root mass was characteristic of the cuttings of border pelargonium rooted in the medium containing 30% of coconut fibre.

2. The best influence on the dynamics of the root increase and their mass – and hence on the final quality of the root system – was exerted by the medium containing 30% coconut fibre used at the earlier date of rooting.

We would like to express our greatest thanks to the Horticultural Company Vitroflora at Łochowo near Bydgoszcz for the free access to the cuttings of pelargonium plants and the glasshouse in the period of rooting. We also want to thank Dastin Bis Ltd. from Komaszyce near Inowrocław, the general distributor of the coconut substrate, for the rooting medium.

REFERENCES

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