Two types of seed beds are used to raise sandal seedlings: sunken and raised beds. Both of them perform equally well under different climatic conditions.
Seed beds are formed with only sand and red earth in the ratio 3:1 and are thoroughly mixed with nematicides (Ekalux or Thimet at 500 g per bed of 10 m x 1 m). Around 2.5 kg seed is spread uniformly over the bed, covered with straw which should be removed when the leaves start appearing on the seedlings. Sandal suffers from a very virulent disease caused by combined fungal and nematode infection. The initial symptom is that of wilting of leaves followed by suddan chlorosis and root decay. On account of this the mortality rate is very high, which can be controlled by the application of nematicide (Ekalux) and fungicide (Dithane). Seeds beds are to be sprayed with fungicide Dithane Z-78 (0.25%) once in 15 days to avoid fungal attack and 0.02% Ekalux solution once in a month to avoid nematode attack.
When seedlings have reached 4 to 6 leaf stage they are transplanted to polybags along with a seed of Cajanus cajan, Alternanthera sessilis (L.) R. Br. ex. Dc, Cassia fistula L., Mimosa pudica L., etc., the primary host for better growth of sandal. Seedlings are carefully removed from beds with all roots intact; roots should not be allowed to dry. Shade can be provided for a week immediately after transplantation. Watering is to be done once a day, but excess moisture is to be avoided. Host plants are to be pruned frequently, so that they do not over grow sandal and hamper its growth. Polybags should contain soil mixture of ration 2:1:1 (Sand: Red earth: Farmyard manure). It has been found that polybags of 30 x 14 cm size are the best. To avoid nematode attack Ekalux of 2 gm/polybag or 200 gm for 1m3 of polybag mixture should be thoroughly mixed before filling the bags. Shifting may be done once in two months to avoid root penetrating soil and grading is to be done once in three months. Weeding is to be done at regular intervals.
Plantable seedlings of about 30 cm height can be raised in 6-8 month’s time. A well branched seedling with a brown stem is ideal for planting in the field.
The problem in Sandalwood Nursery
Sandal cultivation has so far been restricted to government controlled lands, reserve forests and protected areas and hence information is lacking on growth, heart wood formation and compatibility with horticultural crops when grown on private lands under intensively managed conditions. The potential of the tree in existing farming or silvi-horticultural systems with horticultural plants as secondary host for improving livelihood and creating employment opportunities and enhancing farm incomes is quite huge especially in semiarid zones due to the less demanding climatic and edaphic requirements of this species. However, availability of Quality planting material (QPM) of sandal from known sources is one the main bottle neck hampering its wide scale cultivation. Traditional methods of preparing potting mixture in 1:1:1 ratio (sand, soil, FYM) and sowing in standard size polybags do not work for raising sandal seedlings since it is a hemi-parasite and has specific media and nursery growth requirements. Standardization of nursery technology for raising good quality seedlings of sandalwood becomes necessary in such a scenario.
Nursery technology for raising quality planting stock of sandalwood
Institute of Wood Science and Technology (IWST) has standardized nursery practices to raise quality seedlings of sandalwood. Seed collection, handling, storage and germination methods have been standardized in IWST after a series of nursery experiments. Freshly collected sandal fruits from IWST seed collection areas are depulped and dried in shade. Seeds are soaked for 16 hrs in Gibbirellic acid (500 ppm) before sowing in germination beds with a dimension of 1x10m composed of fine river sand with underlying gravel layer. Seedlings at 2-3 leaf stage are pricked and transplanted in 270cc root trainers containing potting media
Consisting sand: soil: compost in the ratio 35:15:50 with Mimosa pudica or Cajanaus cajan as primary host. Media is supplemented with NPK + micronutrients as foliar spray at 15 days periodic intervals. As prophylactic measure Dithane M-45 (0.25%) and Ekalux (0.02%) are sprayed at monthly intervals. Healthy plantable seedlings having height of 30-50 cm and collar diameter of 3.0 mm turning brown at the base, referred to as quality planting stock is ready in 6 months time. The production cost per seedling works out to around Rs 10/- excluding supervisory cost and capital investment cost on infrastructure.
Economics of raising QPM stock of sandal seedlings
Sandal should ideally be raised in root trainers rather than polybags as the root system is far more established and better in root trainer raised seedlings as compared to polybagged raised ones and showed better results in growth and establishment in field. However an initial infrastructure investment by way of root trainers and stands has to be incurred. If recurring costs alone are considered then root trainer seedlings have a lower production cost of Rs 6.26 per seedling as compared to Rs 6.45 per 1500 cc polybag seedling which is mainly due to lesser quantity of consumables (sand, compost etc) used. Moreover the root system development and haustorial association with primary host redgram in the case of sandal seedlings raised in 270cc root trainers is far better than polybagged seedlings. These seedlings were also found to establish perform much better in field conditions.
Sandal Plantation Technology and Economics
Sandal agroforestry models established in Nallal, Muddenahally and Bevanahally have been used for computation of economic benefits In sandal agroforestry, a spacing of 6x3 m with amla at the same spacing in between sandal in quincuncial design of planting appear to be promising. This spacing also ensures cultivation of agricultural crops like horse gram or field bean or low spreading legume fodder during the initial years. The cost of raising sandal based agroforestry plantations may be marginally higher than raising sandal block plantations due to additional intercultural operations. However this may be more than offset by periodic additional returns from horticultural crops. Sandal plants can be expected to establish and perform well with intercropping since periodic intercultural operations improve soil physio-chemical properties.
Problems in Provision of Sandalwood Seedlings
Low Quality of Seed
Quality of seed depends on conditions of mother trees. The ideal mother tree should be more than 20 years old, healthy and having high santalol. The decreasing number of sandalwood mother trees stocked makes obtaining high quality seed difficult.
Competition for Nutrients
Sandalwood is hemyparasite plant, meaning that the plant should have a host which provides some nutrients for the sandalwood plant. Nutrition competition arises between sandalwood and the host plant.
Lack of Water
The moisture content of seedling media is an important factor in sandalwood seedling nurseries. High humidity will decrease the aeration condition such that it is unsuitable for sandalwood seedling growth. Therefore, the regulation of moisture content plays an important role in producing high quality seedlings.
Seedling Medium of Germination
The type of sowing medium can influence the aeration and drainage capacity and both will influence the survival of seedlings. Some treatments about medium factors are explained in Table 2. Sandy material was the better medium for germination and the lowest germination percentage was on soil material. This factor related to the aeration, drainage and temperature condition.
Sandalwood needs shade in the nursery. High intensity of light can kill the seedling.
Pests and diseases
The common disease in nurseries is londoh (a whitish decay fungi) and the most common pest is leaf worm, both of which can quickly kill a large number of seedlings.
Quality of Human Resources and Management Institution
Most of the local communities do not have the knowledge, skill and technology to develop sandalwood plantations. Individual stakeholders have already tried to develop plantations in their own way without coordination with each other. Therefore, it is difficult to find an area of sandalwood plantation with good growth anywhere in the field.
PROPOSED SOLUTIONS TO SANDAL WOOD SEEDLING PROBLEMS
Sandalwood seedling problems as described above can be solved by conducting some techniques and research, including:
Ø Low seed quality can be solved by selecting the seed before planting. Desirable physical qualities of seed include relatively large size, light brown colour and white flesh.
Ø Nutrition competition can be solved by cutting and pruning the host plants in an appropriate way and intensity. Choosing the right host plants is the important factor for the sandalwood nurseries. The species and the time to plant host trees is a critical factor for success in seedling producing. The root of the seedling should not protrude out of the plastic bag, because this will inhibit seedling growth in the field. Therefore, the bigger the plastic bag size, the better the seedling growth.
Ø It is important to arrange and check the humidity of the medium for germination and seedling periodically. Watering the seed can be done each two days. In the rainy season, the seedling must be protected with covering/shading by plastic material to hinder the splashing of rain drops so the humidity of the medium ramains favourable.
Ø Optimal sunlight intensity is about 50%. The sunlight intensity can be arranged by using shade combinations. The most common shade materials used in nurseries are coconut leaf, imperata leaf and net shading.
Ø To prevent fungi decay, the media should be sterilized or treated with fungicide on the seeds before sowing. Insecticide treatment with a karbaril active compound can be used to control leaf worm.
Ø Capacity building can be done by a learning process and practicing of knowledge, skill and technology for sandalwood nurseries in a simple way and step-by-step, especially for the local communities. This capacity building can be targeted towards a small group community in the village which has been selected. Besides the technical aspect, the social, economic and environmental factors are also a part of the learning process. The final question for them is how to develop a sandalwood plantation in a small-scale forest and how to organize in their own land in the village.
Ø Viswanath, S., Geeta Joshi, Rathore, T.S., Technology Package for Raising Sandal Plantations from Quality Planting Material (QPM) Stock of Sandalwood Seedlings, Report of Institute of Wood Science and Technology, Bangalore.
Ø Tigor Butar Butar, S.Agung Sri Rahardjo and I Made Widnyana, Sandalwood nursery problems and remedial measures in west Timor, Report of Improving the Triple Bottom line Returns from Small-scale Forestry. Chapter 46. pp. 411-414,
Ø Troup, R.S., (1921), The silviculture of Indian Trees, Clarendon Press, Oxford, 3: 817.
Ø Troup, R.S., (1991), Concentric rings in sandalwood, Indian Forester, 45:57-63