Effect of trimming and mycorrhizal inoculation on the growth of Hopea odorata rooted cuttings

Effect of trimming and mycorrhizal inoculation on the growth of Hopea odorata rooted cuttings

Patahayah, M. and Lee, S. S.

Forest Research Institute Malaysia, 52109 Kepong, Selangor, Malaysia

Tel: 603-62797119 Fax: 603-62731427 E-mail: fatah @frim.gov.my

Abstract

A nursery trial was set up at the Forest Research Institute Malaysia (FRIM) to determine the effect of trimming and ectomycorrhizal (ECM) inoculation on the growth of Hopea odorata rooted cuttings. This study consisted of four treatments T1 – ectomycorrhizal inoculation, T2 – trimming, T3 – ectomycorrhizal inoculation + trimming and T4 – untreated control (without ectomycorrhizal inoculation and without trimming). Hopea odorata cuttings were inoculated with an indigenous ectomycorrhizal inoculum, Tomentella sp. in peat: vermiculite. Cuttings were inoculated one week after transplanting into polybags containing a standard potting mix. Trimming was carried out at two-week intervals when the plants showed signs of producing a second leader. The height of the plants was measured at monthly intervals. The plants were harvested after six months. Total root length of each plant was measured and shoot biomass was calculated based on oven dry weight. Cuttings with ectomycorrhizal inoculation had better growth in terms of height, total root length and shoot biomass compared to non-inoculated plants. The combination treatment of ECM inoculation and trimming (T3) produced plants with the best height growth while the treatment of ECM inoculation alone (T1) produced plants with significantly better root length and shoot biomass. Trimming alone (T2) produced plants with the lowest growth performance for all parameters. No significant difference in root biomass was observed regardless of the treatment. Application of mycorrhizal inoculation is recommended to improve growth of plants in the nursery. Further research on ectomycorrhizal inoculation should also be carried out especially with other dipterocarps to better understand the symbiotic activities of both the fungus and the host.

Keywords: Hopea odorata, ectomycorrhizal inoculation, trimming, cuttings

Introduction

Mycorrhizals have long been reported to improve plant growth and survival of plant at seedling stages. However, in Malaysia implementation of inoculated plant with mycorrhizals in nursery still under studies, as many factors that influence both the mycorrhizal and its host were not well understood. In FRIM, research on mycorrhizal activities is being focus on its important use in the rehabilitation activities either on dipterocarp or Acacia species. In the nursery, synthesis studies being conducted to determine the suitability of the ectomycorrhizal fungi and the hosts. Repeated studies on Hopea odorata, Dryobalanops aromatica, Shorea leprosula (Aminah et al. 2002), Dipterocarpus alatus and Shorea glauca (Chang et al. 1994) revealed that only Hopea odorata gave better result when inoculated with ectomycorrhizal.

In most studies related to mycorrhizal trial, cuttings were used, as it can minimize contamination compared to those from seeds. Therefore, most of the dipterocarp species, will be firstly screened for cuttings production. Aminah (1991) listed eleven dipterocarp species that showed ability to root by stem cutting. Hopea odorata is being used in this study due to its stock availability and good growth performance. Hopea odorata is a favourable dipterocarp species for plantation due to its ability to grow well in harsh condition and withstand drought, and is often selected for landscaping because of its shape. In nursery, it can be easily propagated en masse through stem cuttings (Aminah 1991, Aminah 1996, Aminah 1991a, Aminah 1991b) and being used in mycorrhizal inoculation trial. Even though the trial produces good results, but in some cases, the results also showed inconsistency in the performance of the growth of H. odorata after inoculation.

Therefore, this study was conducted to determine other factors that limit the symbiotic activities on the growth of the host plant by doing trimming. In order to maintain vigour, trimming is being practised from the beginning at the seedling stage, besides it can generate new growth and improve the appearance of a tree.

Materials and methods

This experiment was carried out at the nursery of Forest Research Institute Malaysia (FRIM). This study applied four treatments:

a) T1 – ectomycorrhizal (ECM) inoculation only

b) T2 – trimming only

c) T3 – ectomycorrhizal (ECM) inoculation and trimming

d) T4 – Untreated control (without ectomycorrhizal inoculation and without trimming).

Hopea odorata cuttings were inoculated with an indigenous ectomycorrhizal inoculum, Tomentella sp. in peat-vermiculite. The peat-vermiculite inoculum of the ectomycorrhizal fungus was produced according to the method described by Yazid et al. (1996). The substrate for inoculum was the mixture of peat and vermiculite (1:9 v/v) amended with Pachlewski’s nutrient medium. The substrate was then autoclaved at 121^oC for 20 min. Then actively growing indigenous ECM fungus, Tomentella sp. (Telephoraceae) was propagated into the sterile substrate and stored in incubator at 25^oC until the hyphae was fully occupied. This process took about one-and-a-half months. This fungus was isolated from ectomycorrhizal roots of a Shorea parvifolia (Dipterocarpaceae) seedling obtained from the nursery of Forest Department at Lentang, Pahang, Malaysia.

Rooted cuttings of H. odorata were produced using the techniques described by Aminah (1991). Cuttings were inoculated one week after transplanting into polybags containing a potting mixture of composted mesocarp fibre. Mesocarp fibre was obtained from a local oil palm mill and had undergone natural decomposition for six months. Each medium was sterilized in a ventilated oven at 100^oC for 72 hours before cooling and mixing to produce the desired media. About 500 cc of the medium was then filled into polybags (14 cm height x 9 cm diameter).

For inoculating H.odorata plants, one heaped teaspoonful of the well colonized Tomentella sp. peat-vermiculite inoculum was placed in contact with the roots during potting. A heaped teaspoonful peat-vermiculite without Tomentella sp. fungus was added to the control plants. Before inoculation into the potting media, the inoculum was leached by washing under running tap water to remove the excess glucose. Fifteen cuttings were used for each treatment and were randomly arranged in four blocks. The potted cuttings were first weaned in the cutting shed for a week before being transferred to a nursery bed. Watering was carried out manually once a day. Weeding and insecticide applications were made when necessary.

Height from the ground level to the tip of the tallest shoot was measured every month starting one month after potting. Trimming treatment was done at two-week intervals when the tallest shoots found to form two leaders. This experiment was terminated after six months. Total root length of each plant was measured, and the shoot and root biomass was calculated based on oven-dry weight. Total root length was recorded during harvested and 10% of the plants were checked for mycorrhizal infection under the light microscope. Hand sectioning was done to confirm the presence of the inoculated ECM and contaminants. The remaining plants were oven dried at 50^oC for 72 hours until constant weight was obtained. Data collected were subjected to analysis of variance followed by the least significant difference (LSD) test. The results of the analysis were considered significant when the probability level was equal or less than 5% (p< 0.05)

Results and discussion

Early examination on root of inoculated plants showed that ectomycorrhizal was formed after 11 days. However, in other study, Tomentella sp. was found to form ectomycorrhizal with H. odorata seedlings which was raised from seed as early as one week using cardboard inoculum (Lee et al. 2002). Persistence of these ectomycorrhizal fungi after commencement of this experiment was proven when 80% of the roots of the inoculated plants were with ectomycorrhizal. This fungal inoculum did persist on the root of H. odorata rooted cuttings even after two years outplanted in a sandy tin tailing area (Lee, pers. comm.). None of the uninoculated plant formed ectomycorrhizal with Tomentella sp., but there are two unknown morphotypes of basidiomycete found and 37% of the plants remain uninfected.

Observation on shoot formation showed that mycorrhizal inoculation do not significantly boost the formation of the first new shoot as 100% of both inoculated and non-inoculated cuttings appeared to shoot within two months.

Table 1 shows the means of the parameters measured on treated and untreated Hopea odorata cuttings after six months. The combination treatment of ECM inoculation and trimming (T3) produced plants with the best height growth while the treatment of ECM inoculation alone (T1) produced plants with significantly better root length and shoot biomass. Trimming alone (T2) produced plants with the lowest growth performance in terms of all parameters. No significant difference in root biomass was observed regardless of the treatment.

Table 1. Means height, total root length, shoot and root biomass of Hopea odorata cutting following trimming and ectomycorrhizal inoculation.

Principal for having a good nursery stock is that the plants must have a quality root system, since seedling with good root system will survive better after planting out. A quality root system defined as being highly branched with many absorbent short roots. Ectomycorrhiza had these advantages. Trimming in the other hand is supposed to stimulate growth, by forcing the development of roots. However, in this study it did not show any significant result unless with the combination of ectomycorrhizal inoculation. Brundrett et al. (1996) listed several factors that may need to be considered if the ECM root development or plant growth is poor. This includes drainage, watering regime, potting mix, fungicides, nutrient supply, pH and fungal inoculum, and rarely to find information related to the physiology of the plant itself.

In the other hand, inoculated plants found to have significantly different growth compared to uninoculated plants. Inoculated plants have significantly better height and root length. It also showed a higher shoot dry weight than uninoculated one, but no significant different on root dry weight (Figure 1).

Figure 1. Shoot and root biomass of inoculated and uninoculated H.odorata rooted cuttings

Figure 2. Relative height of inoculated and uninoculated H.odorata rooted cutting during six-month study period

The relative height of both inoculated and uninoculated plants did not show any significant differences during the first five-month study period, but drastically changed on the sixth month. There was an increment on the sixth month for the inoculated plants, but the relative height of the uninoculated plant remained decreasing (Figure 2). It may suggest that the effect or the benefit of the ectomycorrhizae may not be seen in a very short time, but for a longer period.

Conclusion

The main objective of mycorrhizal inoculation is to increase the yields of plant grown for plantation. Significant result in this study indicates that proper mycorrhizal inoculation can greatly benefit seedling growth and should be recommended to improve growth of plants in the nursery. Further research on ectomycorrhizal inoculation should also be carried out especially with other dipterocarps to better understand the physiological of the plant host and symbiotic activities of both the fungus and the host.

Acknowledgement

This study was conducted as part of the European Union and IRPA project funded under Contract No. ERBIC 18 CT98 0319 and EA001-01-04-01-0079. Technical assisstance from the staff of the Pathology Unit, FRIM is also appreciated.

References

Aminah, H. 1991. Rooting ability of stem cuttings of eleven dipterocarp species. Malaysian Journal of Applied Biolog 20(2): 155–159

Aminah, H. 1991a. A note on the effect of leaf number on rooting of Hopea odorata stem cuttings. Journal of Tropical Forest Science 3: 384–386

Aminah, H. 1991b. A note on growth behaviour of branch cutting of Hopea odorata. Journal of Tropical Forest Science 3: 304–305

Aminah, H. 1996. Rooting of Hopea odorata cuttings from coppice shoots and the growth performance of rooted cutting at nursery satge. Journal of Tropical Forest Science 8: 273–279

Aminah, H., Patahayah, M. & Lee S. S. 2004. Effect of potting media and indigenous ectomycorrhizal inoculum on Hopea odorata rooted cuttings in nursery. Proceedings of ‘Persidangan Biologi Kebangsaan 2003’.14–16 December 2003, Ipoh, Perak, pp. 34–36.

Aminah, H., Lee S. S. Patahayah , M., Chong, W. S. and Lapeyrie, F. 2002. Effect of Ectomycorrhizal fungal extracts and indole acetic acid (IAA) antagonists on rooting of Dryobalanops aromatica and Shorea leprosula stem cuttings. Proceedings of the International Workshop of BIO-REFOR, 7–11 Oct. 2001, Tokyo. Pp. 99–101.

Brundrett, M., Bougher, N., Dell, B., Grove, T. and Malajczuk, N. 1996. Working with Mycorrhizas in Forestry and Agriculture. ACIAR Monograph 32. 374 pp.

Chang, Y. S., Lee, S. S., Lapeyrie, F and Yazid, M. S. 1994. The competitiveness of two strain of Pisolithus tinctorius on seedlings of three species of dipterocarps under nursery and field condition: preliminary results. In Proc. Internatioal BIO-REFOR Workshop, Kangar, Malaysia. BIO-REFOR, IUFRO/SPD: 208–212

Lee, S. S., Patahayah, M and Lapeyrie, F. 2002. Exotic vs indigenous ectomycorrhizal fungi for inoculation of dipterocarps. Proceedings of the International Workshop of BIO-REFOR, 7–11 Oct. 2001, Tokyo. Pp. 84–87

Yazid, M. S., Lee, S. S. & Lapeyrie, F. 1996. Mycorrhizal Inoculation of Hopea odorata (Dipterocarpaceae) in the nursery. Journal of Tropical Forest Science 9: 276–278

Sources: 8th Round-Table Conference on Dipterocarps

Latest news

• Project: Research on selection and breeding of Acacia hybrid and Acacia auriculiformis for timber plantation in main ecological regions
• National seed orchard of Pinus merkusii
• National seed orchard of Acacia auriculiformis
• National seed orchard of Acacia mangium
• National seed orchard of Eucalyptus camaldulensis

Oldest news

• Growth and photosynthetic rate responses of Shorea platyclados seedlings to nitrogen application
• Research on formulation of scientific and technological basis for supplying improved planting materials of forest trees
• Development of technologies for improved propagation of Sinocalamus Aff Latiflorus McClure through cuttings/ tissue culture
• Preliminary results of hybridization of some eucalypt species
• Research on the selection, breeding and propagation of main forest tree species used in plantations