Applied Research on Mass Vegetative Propagation of Planting Stock
This method has been found particularly effective in Anisoptera marginata, Shorea smithiana, S. laevis, S. leprosula, S. ovalis, S. blanco, and S. pauciflora stem cuttings (Smits and Yasman, 1988) amongst a list of 60 species successfully propagated. About 90 to 100% rooting is obtained by using this method. A large experimental nursery adopting this technique has already started for commercial production at the Wanariset Research Station of the Indonesian Agency for Forestry and Research and Development, Samboja, East Kalimantan. The PT Inhutani I Kongnah timber estate in East Kalimantan produces about 500,000 cuttings per year, using this method, for their planting programme.
The “bubble bath” structure
Three types of propagating tank are being used, viz, elevated concrete tank, ground level concrete tank, and wooden plank with plastic lining tank. The latter is a new innovation intended for use in remote areas where a temporary nursery is more practical and economical. The tank has a dimension of 1 m (W) × 5 m (L) × 0.4 m (deep) and is constructed inside a greenhouse. An aerator or air compressor, similar to that used in aquaria, is attached at the inner side of the tank to keep the rooting medium fully aerated and for promoting rooting and preventing fungus contamination. Good aeration of the rooting medium is very critical to successful rooting. Stem cuttings are inserted in the middle slot of a rectangular frame, 12 cm wide and one meter long, made of dried palm fibre (bristle) firmly gripped by an aluminum spline at both sides and ends. (The black coloured bristles block light from penetrating through to the basal ends of the cuttings which hang in solution). White hard plastic or glass sheets are placed on top of the tank to maintain the desired humidity (over 90%). Wet gunny sacks are placed on top of the glass or plastic to reduce penetration of sunlight, decrease the rate of evaporation and to keep the temperature inside the “bubble bath” tank at the optimum level (23°C to 26°C) for rooting.
Plate 1. The `bubble bath" tank
Plate 2. The aerator terminals are attached to the inner side of the tank with the air nozzle submerged in the rooting water medium.
Plate 3. Stem cuttings inserted in the middle slot of a rectangular frame, 12 cm wide and one meter long, made of dried palm bristle firmly gripped by an aluminum spline at both sides and ends.
Source and collection of cuttings
The top portion or vertical (orthotropic) shoots of seedlings about 10–12 cm long with three (3) mature leaves are taken from a “hedge orchard”. Only orthotropic shoots are collected, since plagiotropic cuttings seldom develop into vertical growing trees. To induce the production of more orthotropic shoots a wide-eyed green plastic mesh is placed on top of the hedge. The seedling “hedge orchard” is established using seeds or wildlings collected from a dipterocarp seed stand (seed production area) or from cuttings, then grown and maintained in the nursery. Wildlings undergo a hardening process in the nursery for a period of 8–12 months before cuttings are taken from them. Seedlings grown from seeds are established for one year, then cuttings are collected. About 240 stem cuttings can be collected/harvested from one square meter area of “hedge orchard” from planting to one (1) year age.
Plate 4. Seedling hedge orchard. The wide-eyed plastic net placed on top of the hedge induces production of orthotropic shoots.
Preparation and treatment of cuttings
Cuttings with at least three (3) well-developed leaves from the upper portion of stems or orthotropic shoots of seedlings about 10–12 cm long are collected using a very sharp pruning shear. The cut is made just below a node. Cuttings root best when the basal 3 mm of the cutting contains a node. The leaf area of these cuttings is reduced by clipping off half of each leaf. The basal portions of the freshly collected cuttings are soaked in a 100 ppm solution of indolebutyric acid (IBA) for a period of one hour, then placed in the slot in the middle of the rectangular frame, so that the basal portion is submerged in aerated water in the bubble bath tank. Another method used is to treat the aerated rooting medium (hydroponics) with IBA at 1 ppm concentration. After the cuttings are set in place, a glass frame or hard plastic cover is placed on top of the tank.
Plate 5. A stem cutting showing the slant angle cut just below a node.
Rooting period
Generally, roots of cuttings occur within 4–6 weeks after treatment. The cuttings are removed from the rooting medium when the root system has fully developed and new green leaves have appeared.
Hardening
Rooted cuttings are transplanted into polyethelene bags filled with forest soil and sand (2:1 ratio), inoculated with ectomycorrhizal fungi. (It was observed that cuttings developed favourable root systems and excellent growth after inoculation with ectomycorrhizae and planting in the field). Then the potted cuttings are placed under fully enclosed shade. This shade is a box-type structure 1m × 2m in size, with inner sidings made of plastic sheet and outer sidings made of Nypa fruticans leaves. During the first week the plants are watered 3–4 times a day to keep the humidity high inside the box. Then gradual exposure to light and decreasing amount of water is applied for a period of 1–3 months. After this, the rooted cuttings are kept in an open transplant bed in the nursery for another 3 months, then outplanted in the field.
This experiment was conducted by FRDC scientists lead by Masano (1992), using two (2) treatments, viz, IBA at 1000 ppm concentration and no growth hormone. Fifty percent rooting was achieved in the treatment with growth hormone and 60% in a control without hormone.
Propagation bed
A concrete bed measuring 1.2 m (W) × 5 m (L) × 0.4 m (deep) with a slightly sloping drain at the center, constructed inside a greenhouse, was used in the experiment. Wooden planks with plastic sheet sidings were placed in the rooting medium to divide it into treatment compartments and prevent the flow of hormone from one block to the other. A triangular frame made of bamboo with transparent polyethelene sheet lining two sides was used to cover the medium. A wet gunny sack is placed on top of the frame to maintain high humidity, reduce air movement inside the propagation bed and to prevent excessive evaporation.
The rooting medium is composed of soil-humus compost-river sand at 3:2:1 ratio, respectively, underlain with coarse gravel.
Source of cuttings
Stem cuttings from the top 10–12 cm portion of vigorous 12–16 months old seedlings raised in the greenhouse were prepared for rooting.
Preparation and treatment of cuttings
Cuttings were taken from the stock plant by cutting just below a node using a sharp pruning shear. Half of the leaf area of three remaining well-developed leaves were trimmed to reduce transpiration and possibility of wilting. The basal ends of 50% of the cuttings were soaked for 30 minutes in 1000 ppm concentration of IBA while the rest of the cuttings were not treated. Both the treated and untreated cuttings were planted immediately in the adjoining rooting medium separated only by a wooden plank with plastic sidings. After planting, the rooting medium was drenched with water to full saturation point. Then, the triangular cover was placed on top of the propagation bed.
Watering schedule
Water was supplied manually to the rooting medium using a sprinkler bucket 3–4 times a day until a stage when new leaves and roots have developed. Thereafter, the amount of water supplied to the rooting medium was reduced to holding capacity.
Hardening
Rooted cuttings showing orthotropic behaviour were transplanted into polyethelene bags (plagiotropic plants were discarded) filled with ordinary garden soil and river sand at 2:1 ratio. These were placed inside the greenhouse, watered 3 times a day to fully saturate the soil in the pot. After 4 weeks, the cuttings were transferred to a partially shaded area outside the greenhouse and the frequency of watering was reduced to 2 times a day. Hardening continued for a period of 6–8 months, thereafter the rooted cuttings were outplanted in the field.
Successful propagation (about 80%) by stem cuttings was achieved with Vatica pauciflora when 0.2% concentration of IBA was applied. Air layering by adding 0.50% concentration of IBA mixed in tale powder applied into the girdled branch induced development of vigorous root systems (80% success) in Shorea palembica and Vatica pauciflora (Halle and Kamil, 1981). The experiment was conducted at BIOTROP, SEAMEO Regional Centre for Tropical Biology, Bogor, Indonesia.
Propagation bed
Washed sand and a mixture of sand and peat moss placed in wooden box were used for rooting media.
Source of cuttings
The cuttings were taken from the vertical axis of young trees, 3–4 years old, and 4–5 m tall. The cuttings measuring 15–20 cm long consisted of several nodes with leaves attached. They were made with sharp knife.
Treatment of cuttings
Concentration of 0.2% of IBA in 95% alcohol (2000 ppm) was prepared and the basal portion (1–2 cm) of the cuttings were dipped in them for about 3–5 seconds and quickly dried off with a fan, then the cuttings were inserted into rooting medium. Polyethelene plastic covers were attached over and around the boxes to seal them from the outside environment.
Watering schedule
The polyethelene cover on the box was opened twice a day and the cuttings were sprayed with mist in the morning (7:00–8:00 am) and in the afternoon (4:00–5:00 pm). Rooting was examined 8 weeks after planting. Frequency and even distribution of mist was critical to rooting.
Hardening
After the roots had grown to 2–3 cm, the cuttings were transplanted into plastic bags containing soil. The nursery was shaded (50%) with green plastic mesh to prevent exposure to extreme temperature. Too early exposure to bright sunshine causes high mortality in the cuttings.
Air-layering experiment
The air-layering powder was prepared by dissolving the 0.5% concentration of IBA in small quantity of 95% alcohol (10 ppm) which was then poured over the talc and mixed thoroughly. The mixture was air-dried and sieved through 0.5 mm mesh screen after which Dithane M45 was added and the mixture sieved again. Using a small brush the layering powder mixture was applied to 2 cm of the branch after removing a 2 cm wide ring of bark. The branch was encircled with a piece of aluminum foil, which was filled with peat moss as rooting medium. The branch was then supported with a string.
After two months the air-layers were inspected. Eighty percent of Shorea palembica and V. pauciflora had successfully rooted.
