MATERIALS AND METHODS

The seeds of S. rostrata were graded into two seed lots i.e., lot-1 and lot-2 depending upon seed size. Grading was done by 2 mm mesh sieve. In Lot-1, there were seeds above 2 mm diameter mesh i.e., large sized seeds. Seeds below 2 mm diameter mesh i.e., small sized seeds. Seeds below 2 mm diameter mesh i.e., small sized seeds were graded as lot-2. Seeds were air dried and were taken separately in polyethylene bags for studying. In case of sand paper scraping, the seeds were scarified by a manually operated sand paper scarifier for 0, 1, 5, 10, 12, 13, 15, 20 and 25 revolutions. Revolution for 12 and 13 times were included in the design latter to get the highest mode of germination due to sand paper scraping. Revolution means circular movement of the telescopic cylinder against the flat metal bars. During revolution, the flat metal bars were just dragged the sand against the abrasive wall of the telescopic cylinder and gouge the seed coat at numerous places. These goused areas served as the points of water entry, For beating, five hundred seeds were tied with cotton cloth and were beaten on a cemented floor for 5, 10, 15, 20, 25, 30, 35, 40 and 45 times maintaining a constant beating height of about 61 cm. Beating here means dashing the seeds themselves to the cemented floor for breaking the seed coat. Five hundred seeds, in case of boiling water treatment, were taken in a clean and thin cotton net and steeped in boiling water for 0, <1, 1, 2, 3, 6, 9, 12, 15 and 18 sec. For concentrated sulphuric acid (98%) treatments, the seeds were scarified by steeping for 0, 8, 12 m, 16 m 20, 24 and 28 minutes within it. The volume of seeds and acid was maintained at 1:2. During steeping, the seeds in acid were stirred with a glass rod constantly. When the treating was over, excess acid was decanted from each beaker. For ethyl alcohol treatment, five hundred seeds were steeped for 12, 24, 36, 48, 60, 72 and 84 hours in a glass bottle (air tight). After the treatment, the seeds were air dried and were set for germination in a sand germination media. The media was kept saturated upto 14 days after seed placement by adding water as and when necessary. The experiment was laid out in a completely randomized design using one hundred seeds per treatment with four replications. Data on germination were collected regularly upto 14 days. Normal seedlings were counted and the germination percentage was recorded. The statistical analysis of collected data were done and the mean values were adjusted by DMRT.

RESULTS AND DISCUSSION

Germination of S. rostrata seed significantly varied with seed size and sand paper scraping/beating, hot water treatment and chemical treatment. The interaction between seed size and sand paper scraping/beating also had significant effect on germination. But there was found no significant effect on interaction between seed size and hot water treatment or chemical treatment. Large seed had higher germination percentage than the small seed (Table 1). This result may be supported by Grant Lipp and Ballard (1964) who found that the larger seeds were less dormant than the small seeds irrespective of the cultivars of subterranean clover. Results in Table 2 showed that large seeds with 13 revolutions gave the highest percentage of germination (97.75%) which was statistically identical for small seeds with 20 revolutions resulting 94% germination. The result is supported by Amin (1987) who observed the sand paper scarification of S. rostrata resulted maximum 94% germination. The lowest percentage of germination was found in control treatment for both the large (13%) and small seeds (12.5%). Interactions between seeds size and sand paper scraping/beating treatments revealed that large seed with less number of revolutions resulted more percentage of germination than small seeds.

Table 1:	Effect of seed size due to scarification on germination of S. rostrata seed
The figures having different letters differ significantly at 1% level by DMRT

Table 2:	Effect of seed size and sand paper scraping and beating on germination of S. rostrata seed
The figures having common letter(s) do not differ significantly at 1% level by DMRT

Table 3:	Effect of steeping period in hot water on germination of S. rostrata seed

Germination percentage due to beating for both large and small seeds increased with the beating number in a minimum rate upto a certain level and then decreased (Table 2).

Table 4:	Effect of chemical treatment on germination of S. rostrata seed

The germination percentage increased when seeds were just steeped in boiling water and then gradually decreased with the increased period of steeping (Table 3). The result suggests that hot water treatment has a positive effect on breaking seed dormancy. This was supported by Gill et al. (1986) that boiling was an effective method for increasing Acacia farnesiana (L) seed germination. Steeping S. rostrata seeds in boiling water for less than 1 second showed the highest percentage of germination (62.63%) and the lowest percentage of germination (18.13%) germination by steeping seeds of S. rostrata in hat water. Treatment with boiling water for 75 sec increased germination from 4 to 78%. Treatment of seeds for more than 75 sec resulted deformed seedlings (Sheelavantar et al., 1989). Germination percentage increased gradually with the period of steeping in conc. H₂50₄ upto 24 min and then decreased (Table 4). The highest percentage of germination (87.38%) was observed by steeping seed in conc. H₂SO₄ for 24 minutes which was at per with 28 min steeping resulting 86.13% germination. This result is in conformity with that of Amin (1987) who observed maximum germination (96%) of S. rostrata in sulphuric acid scarification. Treating S. rostrata seeds with conc. H₂SO₄ for 30 min increased germination from 12 to 94% (De and Rerkasem, 1992). Steeping in ethyl alcohol was identical to control and was the lowest. Ethyl alcohol had no effect on breaking dormancy of S. rostrata seed. This may be fact that erotion and incision to the seed coat by sulphuric acid treatment made the hard seeds permeable to water i.e., increased germination percentage.