Abstract
Effects of soil moisture on the growth and seed production of Paspalum urvillei Steud., a perennia lgrass weed in sugarcan fields, were investigated under 20, 32, 58 and 64% (w/w) soil moisture conditions. The following results were obtained:
1. Plant height increased the with the increase of the soil moisture level. Plant height in the maturity period was maximum at 64% level and minimum at 20% level. Approximately the same results were obtained for the tiller numcer.
2. Among the characters associated with productivity, top dry matter weight, root dry matter weight and total matter weight (top dry matter weight plus root dry matter weight) were the largest at 64% level and the smallest at 32% level.
3. Similar results were obtained for the characters associated with seed production, namely, panicle number per plant, panicle weight per plant, panicle weight and 1, 000 seed weight.
4. Percentage of productive tillers was the highest at 64% level and the lowest at 32% level.
5. In the characters associated with weight growth increment, phenotypic plasticity was highest for the top dry matter weight. In the characters associated with seed production, phenotypic plasticity was highest for the panicle number per plant and lowest for 1, 000 seed weight.
6. In this weed, growth and seed production are enhanced especially in areas where high levels of soil moisture occur and effective control is therefore difficult. This fact should be taken into due consideration in any program for the cultivation of sugarcane in such areas.
