Abstract
The present study was conducted at the Agronomy Field Laboratory, Bangladesh
Agricultural University, Mymensingh from June 1996 to March 1999 with the objectives of
determining the effect of (i) planting material and stage of harvest on the yield and germination
of Sesbania rostrata, (ii) date of seeding and shoot mutilation on the yield and seed germination
of S. rostrata, (iii) dormancy breaking treatments on the hardseededness by physical and
chemical methods namely, concentrated sulfuric acid treatment, hot water treatment at 70°C, hot
water treatment at 90°C, sand paper scarification, dry heat treatment and wet rubbing
scarification and 12 storage period viz., 2, 4, 6, 8, 10, 12, 14, 16,18, 20, 22 and 24 months for
improving seed germination in three seed lots of S. rostrata and (iv) stage of maturity and
storage duration on the field performance of S. rostrata. Of the three planting materials viz.,
seed, seedling, and cutting, planting with seedling in mid-August was the best which yielded the
highest (1.71 t ha¹) seeds. The highest seed yield was obtained (2.92 t ha}) when the crop was
harvested at 60 days after anthesis. Germination percentage was the highest when the crop was
harvested on 50-60 days after anthesis. Seed yield differed significantly with the seeding time
and with shoot mutilation. Sowing of seeds in June produced the highest seed yield of 1.90 t ha¹.
Without shoot mutilation, highest seed yield of 2.13 t ha¹ was obtained from June sowing. Date
of seeding and shoot mutilation had no significant effect on seed germination. Concentrated
sulphuric acid, wet rubbing, sand paper, hot water (90°C) and hot water (70°C) scarification
significantly increased seed germination in S. rostrata up to 92.21%, 90.74%, 88.79%, 88.29%
and 84.54%, respectively. In all methods, treatment effects varied among seed lots due to
variable proportion of hard seeds. The dry heat method of seed scarification was found to be
completely ineffective in improving germination percentage. Concentrated sulphuric acid
treatment appeared to be the best method for breaking hardseededness. Maximum germination
was obtained with 40 minutes soaking in acid in all the three seed lots. Seed scarification by wet
rubbing was almost as effective as scarification with acid. Maximum germination was obtained
with 5 minutes wet rubbing in all the three seed lots. Sand paper scarification was also effective
in breaking hardseededness. The highest germination was obtained with 10 minutes scarification
in all the three seed lots. The hot water method at 90°C also appeared to be effective treatment
for breaking hardseededness as the acid treatment, wet rubbing and sand paper method. Its
ability to increase germination up to 88.29% as demonstrated its potential as an inexpensive
method for seed treatment. To reach the germination peak in all the three seed lots needed 60
seconds hot water treatment. Seed scarification by hot water at 70°C was not effective as
scarification with sulphuric acid, wet rubbing, sand paper and hot water (90°C) method in
breaking hardseededness. But, it proved to be a potential method for seed scarification with 80
minutes soaking for all the three seed lots. Seeds of S. rostrata were safely stored for up to 24
months at room temperature without any loss in germination in plastic container. Neither stage
of maturity nor storage duration had any significant effect on the field performance of
S. rostrata.