Clonal propagation of teak (Tectona grandis L.f.)

Teak is one of the high quality timber trees of India. In Kerala, about 70,000 ha is under teak plantations. Teak plantations are traditionally raised from seeds. Since, no focussed attention was given to genetic improvement of teak, the productivity of teak plantations in Kerala is on the decline. As a step to overcome this, attempts are being made by KFRI for cloning of candidate plus trees (CPTs) of teak to raise superior planting stock. A technique standardised at KFRI for cloning of CPTs of teak involves production of juvenile shoots and rooting them. The procedure is described below.

Production of juvenile epicormic shoots

Large branch cuttings in the diameter range of 3 -10 cm are collected from the crown of CPTs and made into 50 cm long pieces. Care is taken not to damage the bark or buds. These cuttings are planted in large polythene bags (18 cm x 12 cm) of 200 gauge filled with garden soil and sand (1:1 v/v) and kept in the mist propagation unit. Intermittent misting is provided (10 seconds misting at an interval of every half an hour) and light, temperature and humidity conditions regulated. Under these conditions, the dormant buds break open and epicormic shoots start growing within 7 -10 days. From each branch, 8 -12 juvenile epicormic shoots are produced within a month.

Rooting of juvenile epicormic shoots

Epicormic shoots, produced on the large branch cuttings, are harvested and used for clonal propagation. Such harvested epicormic shoots should have attained 15 to 20 days’ maturity and have a length of 10–15 cm with 2 to 3 pairs of leaves on them. While preparing these epicormic shoot cuttings for rooting, the apical buds and leaves are kept intact. The distal halves of leaf laminae are removed in order to minimise desiccation during rooting. These shoot cuttings are treated with indole butyric acid (IBA) at a concentration of 6,000 ppm prepared in talc and planted in vermiculite-filled root trainers. The treated cuttings are kept in the mist propagation unit to provide intermittent misting under controlled conditions of light and temperature. Within a period of 30 to 45 days, the shoot cuttings produce roots. The rooted cuttings are transferred to polythene bags (12 cm x 6 cm) filled with soil and sand (1:1) and are kept in hardening chamber for about 40 – 60 days. The properly rooted and hardened cuttings could be taken out for field planting. By this method it is possible to propagate large CPTs of over 40 years and also clone these superior trees on a large scale.

Presowing treatment for teak seeds

Weathering (repeated soaking of seeds in water during night followed by sun drying) for two to three weeks is, by far, the best method known for improving germination of teak seeds. However, germination can be phenomenally improved by removing the felty mesocarp (portion between calyx and stony endocarp) by termite feeding. For this, teak seeds are spread to a height of 5–7 cm on termite infested open ground for about two weeks by which time most of the seeds will be fed by termites. Seeds with only endocarp can be separated by sieving through a 9 mm sieve. Wetting the ground before spreading seed can improve termite activity.

Control of white grubs in teak nurseries

The larvae of beetles of the family Scarabaeidae are known as white grubs. They attack the roots of young teak in nursery. Most of them belong to the genus Holotrichia. Two insecticides, viz., Phorate (Thimet 10 G) and Carbofuran (Furadan 3 G) are recommended for control of white grubs. Apply phorate 30 g per standard bed (12 m x 1.2 m) or carbofuran at the rate of 75 g per bed. Mix the insecticide with a handful of sand and sprinkle uniformly in the bed. The granules left on the teak leaves may be shaken off to the ground. If the soil is dry, drench the bed with water ensuring that the insecticide granules are not washed away. Repeat the treatment if damage continues.

Standardization of root trainer technology for Tectona grandis, Eucalyptus tereticornis, E. grandis, E. globulus, E. camaldulensis, Acacia auriculiformis, A. mangium and Paraserianthes falcataria

A package of practices for production of root trainer seedlings using compost, for Tectona grandis, Eucalyptus tereticornis, E. grandis, E. globulus, E. camaldulensis, Acacia auriculiformis, A. mangium and Paraserianthes falcataria is available.

Fertilizer application for teak

Fertilizer application is ideally done based on a soil analysis report. However, the following recommendation is made for one- to two-year-old plantations of teak grown in Kerala.

Locality	Species	Period
Achencoil & Aryankavu, Nelliampathy (Kerala)	C. hookerianus	March-May, September-November
Nilambur (Kerala)	C. metzianus	April-May
Peerumedu (Kerala)	C. pseudotenuis	March - April, August- October
Kollam (Kerala)	C. rotang	April-May
Achencoil & Aryankavu, Nelliampathy (Kerala)	C. thwaitesii	March-May
Anmod/Agumbe (Karnataka)	C. karnatakensis	April-May
Honnavar (Karnataka)	C. lakshmanae	April-May
Agumbe (Karnataka)	C. lacciferus	May-June
Makkut (Karnataka)	C. stoloniferus	May-June
Upper Kodayar (Tamil Nadu)	C. dransfieldii	April-May

The above fertilizers may be applied in two equal split doses during South-West (June-August) and North-East (October-November) monsoon and when the rains are less intense. Application may be made in 5-10 cm deep furrow 10 cm away from the plant. The furrows may be closed after application.

Laboratory rearing of teak defoliator (Hyblaea puera) using artificial diet

yblaea puera can be reared in the laboratory for experimental purposes and production of NPV, under artificial diet. Ingredients and preparation of the diet are given below. Ingredients of the diet (14 items): Agar (20 g), Kabuligram flour (Cicer arietinum) (100 g), Casein (purified) (30 g), Yeast extract powder (10 g), Teak leaf powder (20 g), Multivitamin and mineral mixture (2 caps), Vitamin E (400 mg), Ascorbic acid (3.5 g), Sorbic acid (1 g), Methyl-parahydroxybenzoate (1.5 g), Streptomycin sulphate(0.25 g), Formaldehyde 10% (2 ml) and Distilled water (1000 ml)

Diet preparation: Agar is added to half the required quantity of distilled water in a beaker, stirred with a glass rod and brought to boil. The beaker is then removed and kept immersed in hot water to prevent solidification of agar.

Kabuligram, leaf powder, yeast extract, sorbic acid, casein/casein hydrolysate, and methyl-parahydroxybenzoate are added to the other half of the distilled water in a blender jar and blended. To this is added the multivitamin mineral mixture, ascorbic acid, streptomycin and formalin, and the mixture is further blended. Agar solution cooled to 60oC, is then slowly poured to the above mixture and blended. The diet is poured while hot into sterilized glass tubes (7.5 cm x 2 cm) up to about one fourth of the tube (About 3.5 ml). This quantity of diet is sufficient for complete development of the larva. One litre of the diet is sufficient to prepare about 300 such tubes. The tubes are then covered with paper and allowed to cool to room temperature.

Transfer of larvae: Larvae initially established on tender teak leaves are transferred to the diet when they are 3-4 days old (second instar). Using a fine camel hair brush, a single larva is transferred to each tube containing the diet. The tubes are then closed with cotton plugs. The rearing is carried out at room temperature (24-26oC), and 81 to 92% relative humidity. The pupae are removed from the rearing containers within 24 hr of pupation and transferred to clean bottles for emergence.

This diet has been found to be useful for rearing the teak borer Aleterogystia (Cossus cadambae Moore) as well.

Baculovirus as a potential bio-control agent against the teak defoliator Hyblaea puera

Baculoviruses are pathogens that attack insects and parasitize them. They are usually less than a thousandth of a mm in size and are composed of double-stranded DNA. In order to get infected, the baculoviruses must be eaten by the host and the infection, is typically fatal to the insect.

Majority of baculoviruses used as biological control agents are of the genus Nucleopolyhedrovirus. This group of disease-causing viruses are very specific to insects and therefore are being extensively used for control of pest insects particularly in developed countries. They are selective in action and do not infect non-target insects, plants, mammals, birds or fish.

The foliage loss of teak caused by the defoliator can be prevented to the extent of 70-76 per cent by timely one time spray of the virus preparation during each outbreak. Spraying protocols have been developed and methods have been standardized to mass multiply the virus on its own host larvae and to produce storable virus preparations for large-scale field applications. The HpNPV is a safe, ecologically acceptable and effective tool for controlling the teak defoliator.