Standardisation of planting stock production techniques for teak (Tectona grandis Linn.f.)
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Date
2020
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Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara
Abstract
The study was undertaken at Tree Nursery of College of Forestry to compare the effect of different pre-treatment methods on seed germination and optimization of fertigation intervals and seed sowing at different spacing for quality teak stump production. Attempt was also made to select ideal potting media and to standardize container type and size for producing quality teak seedlings. The treatment combination of termite scarified seeds + Alternate wetting and drying (AWD)-3 days gave the highest germination percentage (92.33 %). This resulted in 18.56 % increase in germination percent against the 73.77 % in the AWD 7 days alone (Standard Pre-treatment followed). The dual advantages of the treatment combination of termite scarified seeds + AWD-3 days with respect to both high a germination percentage and the lesser number of days required for the pre- treatment of teak seeds is an important highlight. Termite scarified seeds gave the highest collar diameter of 1.46 mm as against the control treatment (0.81 mm) after 30 days of germination. The superiority of this treatment was evident, in most of the seedling growth characters in the nursery also, as in shoot length (6.43 cm), root length (13.04 cm), total seedling length (19.48 cm), dry weight (0.20 g) and vigour index (14.91). Mechanical scarification also has shown advantage over the untreated seeds as it followed as the next best treatment in germination percentage and in most of the early seedling growth characteristics. Hence, in situations where the suitable subterranean termite cannot be assured, mechanical scarification using the mechanical scarifier is recommended. For quality teak stump production, at 180 days, the maximum collar diameter (23.31mm) showed by Fertigation at 7 days interval was significantly superior to all other treatments. Moreover, at 180 days, all the fertigation treatments reached the minimal collar diameter criteria of 1-2 cm were statistically distinct from the no fertigation (control) treatment. All the fertigated treatments attained collar diameter of 2-3 cm criteria for better teak stump production. It is also proved that even the least frequent fertigation at 21 days application resulted in the collar diameter of (22.66 mm) at 180 days of growth period. Hence, fertigation with 0.2 % N: P: K (19:19:19) in equal proportion at 21 days interval can be recommended for producing seedlings for better stump production. Seed sowing at 10 cm x 10 cm also reached required collar diameter for stump production. That means, 1000 numbers of utilisable seedlings are available for stump production from a standard nursery bed of 10 m x 1m at 180 days of seedling growth. At 180 days, the treatment interaction F1 X S3 (Fertigation at 14 days interval X Spacing at 30cm X 30cm) showed the maximum collar diameter (34.88 mm) followed by F2 X S3 and F3 X S3 (32.00 and 31.75 mm), these two were on par with each other. Taking into account the number, the treatment combination S1 X F3 (10 cm X 10 cm with 21 days intervals of fertigation) is recommended as it produces 1000 numbers of seedlings fit for better stump production from a standard nursery bed size of 10 m X 1m. The treatment S1 X F4 (10 cm X 10 cm) with no fertigation also reached the minimal collar diameter (11.51 mm) criteria of 1-2 cm. Good correlation existed between root growth potentials and most of the seedling characteristics needed for good quality teak stump with six months of seedling growth. Among the potting media the maximum seedling length (138.00 cm), collar diameter (8.77 mm), total dry weight (17.77 g) and the highest quality index (0.98) recorded in M3-Soil+ Rice husk+ Vermicompost in the ratio of 2:1:1 as against the standard potting media M5 (Soil+ Sand+ FYM) normally used for raising seedlings. Apart from the observed improvement in plant growth, the production cost of planting stock was found comparable for M3 (soil+ rice husk+ vermicompost) 2:1:1 mixture (₹ 9.09 / plant) as against the cost for standard potting mixture (₹ 9.01 / plant) and the treatment M4-Coir pith+ vermiculite+ perlite was found as the costliest (₹ 13.02 / plant). Both from the seedling quality and from the economic point of view, the treatment M3- Soil+ rice husk+ vermicompost was emerged as the best. Among the polythene bags, 30 cm x 25cm (T1) raised seedling exhibited maximum number of leaves (15.25), leaf area (4025.95 cm2), shoot length (106.89 cm), collar diameter (13.50 mm), the number of primary lateral roots (58.12), length of primary lateral roots (38.96 cm) maximum root length (48.74 cm), total dry weight (60.37 g) and quality index (4.56) at 90 days after transplanting. Among the different root trainers, 300 cc raised seedlings showed maximum number of leaves (11.12), leaf area (435.08 cm2), collar diameter (6.91 mm), shoot length (27.09 cm), root length (23.80 cm), total seedling length (50.90 cm), number of primary lateral roots (51.25), length of primary lateral roots (19.80 cm), leaves dry weight (2.11 g), shoot dry weight (3.46 g), total dry weight (6.61 g) and quality index (0.84) as against the T6-Root trainer of 150 cc (Standard size/control). The production cost of planting stock was found (₹ 9.09 and ₹ 7.89 / plant) for T4-Root trainer of 300 cc and T5-Root trainer of 200 cc and T6-Root trainer of 150 cc - Standard size/control (₹ 6.99 / plant). From the results of the study, it is advisable to adopt root trainer of 300 cc only if the additional cost of ₹ 2.10 can be spent per seedling, otherwise go for the standard size of 150 cc for there was no distinct advantage of adopting the next bigger size of 200 cc. The prominent managerial inputs form this study for teak nursery production forestry include development of standard protocols for pre-treatment, seed sowing spacing, potting media, size of the polythene bags and root trainers. The package for quality teak stump production was also standardised.
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PhD