Abstract:
Weedy rice (WR) (Oryza sativa f. spontanea)was first reported in 1990 and
it is occurring with varying population densities in all agro-ecological zones in Sri
Lanka. Location field trial was conducted on rice field in Malwatta area during May to
August 2018 in Yala season to study the effect of cultural practices on growth and yield
ofweedy rice and direct seeded rice (Oryza sativa)(AT362). Seven rice farmers having
one rice field per farmer, F1, F2, F3, F4, F5, F6 and F7 from7 different sampling sites
were selected for this study. Preliminary Study of the infestation of weedy rice was con
ducted The sites were selected on the basis of previous observations of the infestation
of weedy rice. It was noted that those farmers followed different cultural practices
from land preparation until harvesting. Information on the cultural practices followed
by the farmers was recorded on a regular basis by individual contact. Samples were
observed and collected from seven rice fields at least 300m distance between plot and
at least 50m between from each sample collection point from each location. Sampling
points were noted as S1, S2, S3. Samples were collected in 3 different stages as
seedling stage, flowering stage and maturity stage. Samples were randomly taken by
using 1 x 1m quadratic frame randomly in the selected field. Di ferent types of 2 f
samples collected in different stages found within the frame have carefully counted
and uprooted from each throw. bags were brought to the laboratory to evaluate the
population, plant height, number of tillers, number of panicles, panicles height,
number of spikelets per panicle, number of grain within 1 m and yield within 1 m . 2 2
The collected data were analyzed statistically and mean differences among the yield
and different farmers under different growth stages were adjudged as per Duncan's
Multiple Range Test (DMRT) at 5% level of significance. The result of this survey
shows that, the source of seed paddy and cultural practices applied by the farmers in
different growth stages impact on the weedy rice population and this leads to impact
on growth and yield of direct seeded rice in the selected area. This experiment
determined the effective control of weedy rice cannot be based on one single practice,
but should rely on a complex management programme based on an appropriate
combination of preventative, cultural, mechanical, chemical and genetic means.
