MSc

A detailed study was conducted at the College of Forestry, Vellanikkara to investigate the effect of seed size on seed characters and germination vigour and the effect of seed size and time of germination on seedling performance of teak (Tectona grandis Linn.f.) during 2001-2003. Most of the fruits were belonging the grades between 9 to 18 mm. 12-15 mm size grade recorded the highest proportion by number as well as the weight per kg of the sample lot compared to 15-18 mm, 9-12 mm and 6-9 mm grades. Size, volume and weight of the individual seeds not differed between the plantations studied. The average emptiness value of the seeds decreased with the increase in seed size. The number of empty, one, two, three and four 'true seeded' seeds increased with increase in seed size grade. The crude oil content of the true seeds ranged between 42 to 33 per cent by weight and that of soluble and total carbohydrate content ranged from 6.42 to 5.12 and 10.72 to 9.61 per cent by weight and these were found to increase with increase in size grade. The insoluble carbohydrate content of 'true seeds' was ranging from 4.5 to 3.8 per cent by weight and it varied significantly between the plantations and Cherupuzha plantation recorded the maximum amount. Protein content of the seeds ranged from 3.7 to 3.6 per cent by weight and it did not vary significantly between the plantations as well as size grades. Poly acrylamide gel electrophoresis of proteins at ph 7 gave similar banding pattern (two bands with Rm values 0.09 and 0.19) for different size grades in all the plantations. Storage of the seeds for one year significantly reduced the germination Size grade of the seeds used to conduct the nursery studies significantly influenced the germination percentage of the seeds as well as the vigour index of the seedlings. The effect of seed size grade and time of germination on seedling characters was significant at all stages of growth of the seedlings with the exception of taproot length, specific leaf area and chlorophyll a content of the seedlings. The seedlings belonging to 15-18 mm grade seeds recorded largest height, collar diameter, internodal length, length of longest lateral roots, leaf area, number of lateral roots, stem dry weight and chlorophyll b and total chlorophyll content at different stages of growth. Seedlings belonging to 9-12 mm seed grade recorded the lowest values of these characters. The leaf, stem and total dry weight of the seedlings at 270 and 360 DAP were found to increase with the increase in size grade of the seeds. Seedlings belonging to 9-12 mm grade showed higher RGR and NAR values compared to that of the seedlings belonging to 15-18 mm and 9-12 mm seed grades in first to fourth week germinants. There was no definite pattern in variation of number of leaves, and root:shoot ratio among the of the seedlings due to size grade of the seeds. With regards to time of germination of the seeds, seedlings obtained from the first week germinants recorded the largest height, internodal length, collar diameter and leaf area at all the stages of growth. Other characters did not show any definite trend due to time of germination. Significant differences due to seed size was absent in all the attributes related to the growth potential of the stumps prepared from 180 days old seedlings. However, the effect of time of germination of the stumps was significant in the number of lateral and tertiary roots per stump and length of the first, second and third longest lateral root. Dry weight of the lateral roots was found to increase with the increase in seed size grade of the stumps obtained from 360 days old seedlings. With regards to time of germination, the stumps obtained from the first to fourth week germinants varied significantly in the number of sprout, length of the second sprout, number of leaves, lateral and tertiary roots per stump and length of the first, second and third longest lateral roots.