AI SearchThe effects of depth of water on growth, yield and weed competition in rice
Call Number: AIT Thesis no. AS-01-13 Material type:
SeriesSeries: Asian Institute of Technology. Thesis ; no. AS-01-13Publication details: Bangkok : Asian Institute of Technology, 2001Description: 47 leavesSubject(s): Online resources: Dissertation note: Thesis (M.Sc.) - Asian Institute of Technology, 2001 Summary: Weeds constitute a group of plants growing where they are not wanted. In lowland rice, grasses, sedges and broad leaves grow and compete with rice for light, nutrient, space and water. Weed infestation primarily constrains rice production by reducing grain yield. In order to control weeds in rice, several weed control methods were discovered. However, rice growers still face many difficulties in solving weed problems. Water management is an indigenous method for controlling weeds in rice. This study was therefore conducted to find out an effective weed management practice to assist rice growers. The preliminary laboratory study confirmed that the depth of water at 0 cm and 2 cm were favorable for rice seed germination and emergence. The water depth above 2 cm reduced germination of rice seeds. In submerged conditions, rice population was reduced, and establishment was little late The highest number of tillers was produced at water depth between 4 and 6, while the lowest at 0 and 2cm. The latter caused heavy weed growth and casualties to rice plants. Removal of weeds at 35 DAS caused significant increases in growth and yield of rice. Number of grains per panicle remained unchanged above 4 cm. There was a reduction of number of productive grains per panicle at 0 and 2 cm. However, removal of weeds at 35DAS reduced the casualties. The 100-grain weight remained unchanged at the depth of water above 4 cm and in the two control treatments. The highest hundred-grain weight was shown at 6 and 8cm. Grain yield of rice increased with increasing the depth of water from 0 to 4 cm, but yield was not significantly different at water depths from 4 to 8 cm without removal of weeds at 35 DAS. When weeds were removed at 35 DAS, there were no yield differences with increasing water depth from 0 to 8 cm. Although yield parameters showed their highest values at different water depths, the optimum conditions for the combined effect on increasing the final grain yield were found between 4 to 6 cm depths.
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A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of environment, Resource and Development
Thesis (M.Sc.) - Asian Institute of Technology, 2001
Weeds constitute a group of plants growing where they are not wanted. In lowland rice, grasses, sedges and broad leaves grow and compete with rice for light, nutrient, space and water. Weed infestation primarily constrains rice production by reducing grain yield. In order to control weeds in rice, several weed control methods were discovered. However, rice growers still face many difficulties in solving weed problems. Water management is an indigenous method for controlling weeds in rice. This study was therefore conducted to find out an effective weed management practice to assist rice growers. The preliminary laboratory study confirmed that the depth of water at 0 cm and 2 cm were favorable for rice seed germination and emergence. The water depth above 2 cm reduced germination of rice seeds. In submerged conditions, rice population was reduced, and establishment was little late The highest number of tillers was produced at water depth between 4 and 6, while the lowest at 0 and 2cm. The latter caused heavy weed growth and casualties to rice plants. Removal of weeds at 35 DAS caused significant increases in growth and yield of rice. Number of grains per panicle remained unchanged above 4 cm. There was a reduction of number of productive grains per panicle at 0 and 2 cm. However, removal of weeds at 35DAS reduced the casualties. The 100-grain weight remained unchanged at the depth of water above 4 cm and in the two control treatments. The highest hundred-grain weight was shown at 6 and 8cm. Grain yield of rice increased with increasing the depth of water from 0 to 4 cm, but yield was not significantly different at water depths from 4 to 8 cm without removal of weeds at 35 DAS. When weeds were removed at 35 DAS, there were no yield differences with increasing water depth from 0 to 8 cm. Although yield parameters showed their highest values at different water depths, the optimum conditions for the combined effect on increasing the final grain yield were found between 4 to 6 cm depths.
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