Online Manual for the Forest Tree Seeds of Kerala

A Kerala Forest Department Funded Project

Dr. K Sudhakara
Professor & Head of the Department
Dept. of Silviculture & Agroforestry
College of Forestry, Kerala Agricultural University, Thrissur 680 656
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Scientific Name  Acacia auriculiformis A. Cunn. ex Benth.
Vernacular name  Acacia (Malayalam); Pencil Maram (Tamil) (Chacko et al., 2002).
Common name  Australian wattle, Australian acacia, Australian babul, Tan wattle (Chacko et al., 2002). Golden shower (Bose et al., 1998).
Synonyms  Acacia monoliformis Griseb., Racosperma auriculiforme (A. Cunn. ex Benth.) Pedley (Chacko et al., 2002).
Family  Leguminosae
Subfamily  Mimosoideae
Origin  Savannas of Papua New Guinea, Northern Australia and Queensland (Ram Parkash and Drake Hocking, 1986).
Distribution  Altitude: from sea level upto 700m (Ram Parkash and Drake Hocking, 1986). Native of North Australia and Queensland. As it grows on very poor soils, it is planted mostly, in the dry regions of India as a shade tree and soil cover crop (Fri, 1983; Chacko et al.,2002). Succesfully raised in Orissa, Karnataka, UP and Maharashtra (Ram Parkash and Drake Hocking, 1986).
Description  Tall evergreen tree, reaching a height of 30 m and a breast height diameter of 60 cm. Trunk is often branched with slightly angular branchlets-dark brown and smooth (Chacko et al., 2002; Bose et al., 1998). Crown is thin and dull green (Ram Parkash and Drake Hocking, 1986).
Flowering season  Flowers are produced at intervals from March to December, most profuse in September to November (Bose et al., 1998).
Fruiting season  February to March (Bose et al., 1998; FRI,1983; Chacko et al., 2002). December to January (Chacko et al., 2002).
Flowers  Small, yellow, scented, in slender axillary spikes towards the end of branches, 4-6 cm long, stamens numerous (CSIR, 1948).
Fruits  Fruit is a pod, 1.2 cm wide, hard, almost woody and much twisted in irregular coils, initially green but turn brown on ripening (Chacko et al., 2002; Bose et al., 1998).
Fruit type  Pod.
Seeds  Shining black with orange yellow coloured aril (Chacko et al., 2002; Bose et al., 1998).
Seed length  0.6 cm (Chacko et al., 2002).
Seed width  0.5 cm (Chacko et al., 2002).
Seed thickness  0.15 cm (Chacko et al., 2002).
Seed weight  30,800 (Rai, 1999) to 71,600 seeds/kg (Doran and Turnbull, 1997).
Seed dispersal  Wind (Ram Parkash et al., 1998).
Seed Collection  Ripe pods are collected from the tree during December-February by lopping off the branches when the pods turn brown (Chacko et al., 2002; Srivastava et al., 2006).
Transportation of seeds  Pods are packed in cloth bags and transported (Chacko et al., 2002).
Seed processing  Ripe pods are sun-dried for 5-9 days until they open out to release seeds. The seeds are well dried before storage (Chacko et al., 2002).
Seed storage  Orthodox. Retain their viability up to 2 years under cool dry conditions in air-tight bottles, tins and earthen-ware pots. The seeds are liable to be attacked by ants (Rai, 1999; Chacko et al., 2002). Seeds can also be stored safely with good germination percentage for 8 months in gunny bags or in air-tight plastic containers (Chaturvedi et al., 2004). For long-term storage, the seeds should be thoroughly air-dried and kept without scarification (Sur et al., 1987).
Viability period  Seeds remain viable for more than one year under normal conditions in sealed tin (Chacko et al., 2002). Viability decreases with an increase in the storage period; and use of storage media help to increase the percentage of seed viability (Khomane and Bhosale, 2003).
Seed emptiness  Low (Chacko et al., 2002).
Seed pre treatment  Seeds are treated by immersing in hot water (80oC) for 10 min and then soaking in tap water for 24 hrs, volume of water being about 20 times that of the seeds (Chacko et al., 2002; Girase et al., 2002; Sinhababu et al., 2007). The water should then be taken off the fire and left to cool. Seeds soaked in acid for 30 min, nicking the seeds, nicking and soaking (30 min) in acid, immersing seeds in hot water for 1-5 min and soaking seeds in acid for 20-30 min etc. also give good germination. Mechanical scarification (rubbing polish paper) and iodine treatments are also quite effective in improving germination percentage (Khan, 2001; Girase et al., 2002; Marunda, 1990; Sur et al., 1987). Hot water treatment influences the height growth of seedlings (Chaturvedi and Das, 2004). Seeds soaked in conc. sulfuric acid (20-70 ml/100 g of seeds) for 30 min and stirring in 50 ml acid/100 g seed for 40 min give 83.3% and 85.0% germination respectively (Natarajan and Rai, 1988).
Germination type  Epigeal (Chacko et al., 2002).
Germination percentage  98.5 (Chacko et al., 2002). 68% (Shiuli Mahmud et al., 2005).
Germination period  3 to 7 days (Chacko et al., 2002). Germination period and germinative energy are reduced with increasing salinity and the germination trends are also changed (Rashid et al., 2004).
Nursery technique  Pre-treated seeds are sown in plastic trays filled with vermiculite or sown in raised nursery beds and watered regularly twice a day. The germinated seeds are potted in polybags of size 20 x 10 cm filled with potting mixture. Seeds can also be sown directly in containers such as polythene bags, root trainers, etc., filled with soil or compost based potting media. Seedlings become ready for planting in three months (Chacko et al., 2002). Soil, sand and FYM at a volumetric ratio of 2:1:2 is the best medium for A. auriculiformis seedlings (Sharma et al., 2004). For large-scale seedling production, polybags of 23 x 15 cm are recommended as the optimal size for raising quality seedlings of A. auriculiformis (Riadh et al., 1995).
Method of propagation  Direct sowing or transplanting of seedling (Ram Parkash and Drake Hocking, 1986).
Vegetative propagation  In vitro propagation: The shoot tips from 12- to 16-day-old seedlings are excised and cultured in Murashige and Skoog medium, supplemented with different concentration of 6 benzylamino purine and napthylene acetic acid. 25-30 multiple shoots will be proliferated. The micro shoots 3-4 cm long are excised and rooted in non-sterile sand. The roots will be initiated after 15-21 days (Asha Karki and Radha Niroula, 2000). Epicormic shoots from pollarding give 90% and those from branch cuttings give 70. The commercial preparation 'Seradix' No. 3 (containing 0.8% IBA) give the best results (Simsiri, 1991).
Pests  Powder post beetles (Sinoxylon anale and Sinoxylon sp.), the leucaena psyllid (Heteropsylla cubana), the coffee borer (Zeuzera coffeae) and flat-headed borers (Sternocera aequisignata and S. ruficornis) (Hutacharern and Choldumrongkul, 1989). The strawberry thrip (Scirtothrips dorsalis), cause bunchy top (loss of apical dominance and development of a large number of side shoots from the axils of the condensed stem) (Ashwath and Houston, 1990).
Diseases  Colletotrichum gloeosporioides, Fusarium semitectum, Phoma sp. are the field fungi recorded on seeds (Mohanan and Sharma, 1988; Chacko et al., 2002). Pink disease (Corticium salmonicolor) causes wilting and dieback of the main shoot beyond the point of infection at any place on the stem, where the affected area is characterized by pink encrustations and canker development (Florence and Balasundaran, 1991). Powdery mildew disease is also reported (Bhat and Hegde, 1991).
Medicinal properties  Methanol extracts of Acacia auriculiformis exhibit antibiotic effects (Pennacchio et al., 2005).
Uses  It is an avenue tree. Bark contains tannin. Wood is used for paper manufacture, yield excellent charcoal that glows well and burns without smoke, used as fuel wood and low cost furniture etc. (Chacko et al., 2002). Under specific conditions, unbleached pulp prepared from the wood is suitable for making writing and printing paper (CSIR, 1948).
Wood properties  Wood has specific gravity of 0.6-0.75 and calorific value of 4,800-4,900 kcal/kg (NSA, 1980). Sapwood and heartwood are distinct. Sapwood yellowish white and heartwood dark brownish in colour. Moderately hard and moderately heavy wood with medium coarse texture. Diffuse porous wood with fairly distinct growth rings (Anoop et al., 2005).
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