Abstract
Field survey on farm operations and seedling establishment in wet-seeding rice culture in the Muda Irrigation Scheme, Malaysia, was carried out in the second cropping season of 1988. Harvesting and land preparation for seeding were almost fully mechanized and the field conditions at seeding time were generally fair except for some small parcels where harrowing was performed only two times. For wet-seeding, tillage performed three times seems to be appropriate. However, in-field drainage was incomplete in some fields due to the undulating topography and slight differences in ground levels among the fields. Low seedling establishment and vacant spots (areas without seedling establishment covering more than 0.5 m2) were observed due to oxygen deficiency associated with incomplete drainage. The rate of seedling establishment was low in the fields under the following conditions: (1) small size, (2) uneven field topography, (3) relatively low ground levels, (4) proximity to irrigation canals and (5) harrowing performed only two times. The total area of the fields, where vacant spots accound for 6.0% or more of the entire area, amounted to about 20% of the combined area for site A, and about 35% site B. These figures in both sites showed that the drainage at seeding time was insufficient, despite the fact that site B was equipped with a tertiary irrigation canal and drainage. The average number of seedlings established at site A was about 160 plants per m2 with the average coefficient of variation of 50%. The coefficients of variation, which depended on the average number of seedlings per m2, were high in fields where the average number of seedlings established was lower. The average number of seedlings established at site A was satisfactory. However, about 20% of the fields exhibited a low rate of seedling establishment with an average value of less than 100 plants per m2 which resulted in a remarkable yield decrease. To promote a high rate of and uniform seedling establishment, in-field and inter-field irrigation and drainage methods and land preparation practices should be improved.
