• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.56 no.2
• /
• pp.134-139
• /
• 2011

This study was conducted to evaluate the weed suppressing effects of two winter cover crops, hairy vetch and rye in foxtail millet and sorghum fields in 2010. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In hairy vetch treated plots, heading of minor cereals occurred early. The heading date was earlier by 1 day and 2 days in sorghum and foxtail millet, respectively. However, rye treatment delayed heading by 12 days and 8 days in sorghum and foxtail millet, respectively. Besides he effect of cover crop on ear emergence of crops, the Besides changed growth-related characteristics. Plant height, chlorophyll content and chlorophyll fluorescence of sorghum ere increased in hairy vetch treatment by 46.4% 88.7% and 7.9%, respectively. In foxtail millet, the characteristics ere also increased by 45.6%, 50.9% and 37.8%, respectively, s compared to control. Yields of sorghum and foxtail millet were increased by 105.1% and 135% as compared o control by hairy vetch treatment, respectively. However, he yields of cereal crops were decreased by rye cover crop treatment, the yields of sorghum and foxtail millet were decreased by 25.8% and 119.1%, respectively. Rye cover crop treatment inhibited crop growth suggesting nitrogen starvation in rye treated plots. In rye treatment, plant height, chlorophyll contents and chlorophyll fluorescence of sorghum ere slightly decreased by 7.1%, 10.8% and 10.8%, respectively, as compared to control whereas the inhibitory effects were greater in foxtail millet. Weed occurrences based n weed number in hairy vetch and rye plots were reduced n weed number in hairy vetch and rye plots were reduced y 27% and 20%, respectively. The smothering effect was weakened or disappeared after heading of crops. Weed number and dry weight in hairy vetch plot were increased by 159% and 55.2%, respectively, as compared to control. The results implied that weed suppressing of cover crops could be reduced drastically after heading of crops.

• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.327-334
• /
• 2014

Light intensity is one of the most important requirements for plant growth, affecting growth, development, survival, and crop productivity. Sunlight is the main energy source on Earth which is energy used by photosynthesis to convert light energy to chemical energy. In this study, the light use efficiency and photosynthetic characteristics of high-quality rice cultivars were evaluated after shading on ripening stage. For the study, we treated of three levels of shade (0, 50 and 70%) on rice at ripening stage and two levels of nitrogen (9 and 18 kg/10a) used three high yielding rice cultivars, such as Boramchan, Hopum, and Honong. The shade was given for the respective plots from heading up to harvesting. We were performed to determine growth survey, SPAD and chlorophyll fluorescence every 10 days interval after shading on ripening stage. At harvest stage, grain yield and yield components were determined. Results of analysis of the results representing the maximum photosynthetic efficiency of PSII, Fv/Fm, and SPAD were decreased by depending on the time at full sunlight. But shade treatments were not changed and a significant difference among cultivars did not appear. Compared with the full sunlight, shade treatments significantly delayed ripening rate and decreased rice quality of cultivated rice. Therefore, rice yield, can be reduced in proportion to the shading density is apparent, the rate of decrease was not observed difference between varieties, when protected from light 70%, and decreased to less than 50%. The adverse effects of low light intensity on the yield and yield components were not able to significantly minimize by the nitrogen level.