• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.182-196
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• 2023

Accurate and timely estimation of crop yields is crucial for various purposes, including global food security planning and agricultural policy development. Remote sensing techniques, particularly using vegetation indices (VIs), have show n promise in monitoring and predicting crop conditions. However, traditional VIs such as the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) have limitations in capturing rapid changes in vegetation photosynthesis and may not accurately represent crop productivity. An alternative vegetation index, the near-infrared reflectance of vegetation (NIRv), has been proposed as a better predictor of crop yield due to its strong correlation with gross primary productivity (GPP) and its ability to untangle confounding effects in canopies. In this study, we investigated the potential of NIRv in estimating crop yield, specifically for corn and soybean crops in major crop-producing regions in 14 states of the United States. Our results demonstrated a significant correlation between the peak value of NIRv and crop yield/area for both corn and soybean. The correlation w as slightly stronger for soybean than for corn. Moreover, most of the target states exhibited a notable relationship between NIRv peak and yield, with consistent slopes across different states. Furthermore, we observed a distinct pattern in the yearly data, where most values were closely clustered together. However, the year 2012 stood out as an outlier in several states, suggesting unique crop conditions during that period. Based on the established relationships between NIRv peak and yield, we predicted crop yield data for 2022 and evaluated the accuracy of the predictions using the Root Mean Square Percentage Error (RMSPE). Our findings indicate the potential of NIRv peak in estimating crop yield at the county level, with varying accuracy across different counties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47
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• pp.1-14
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• 2002

Development of crops with high quality as well as various beneficial functions is necessary to satisfy consumers being interested in their health and to enhance a competitiveness in the international market of agricultural products. What we have achieved so far from our research on crop quality was not sufficient since we often neglected sensory feature of crop products such as eating quality but in many cases, we put more emphases on nutrient contents, physico-chemical properties, and out-appearing features of the products. Therefore developments of sensory elements and technique for evaluation with a priority given to eating quality of each of an individual crop are important and very urgent to be solved in Korea. An endeavor to develop bioactive crops is necessary and resonable but aspects of both productivity and economy with a special emphasis on the original purposes such as production of energy and nutrient for human life must be considered. The development of more concrete ideas for crop functionality is essential before any research goes further.

• Proceedings of the Korean Society of Crop Science Conference
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• 1986.06a
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• pp.72-73
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• 1986

• Proceedings of the Korean Society of Crop Science Conference
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• 1989.02a
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• pp.84-85
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• 1989

• Proceedings of the Korean Society of Crop Science Conference
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• 2001.09a
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• pp.180-181
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• 2001

• Proceedings of the Korean Society of Crop Science Conference
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• 2001.09a
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• pp.186-187
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• 2001

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.10a
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• pp.202-202
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• 2017

• Proceedings of the Korean Society of Crop Science Conference
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• 1989.05a
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• pp.64-65
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• 1989

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.4
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• pp.275-280
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• 2013

We examined the use of basic forage data and indicators of forage productivity in different regions of Korea. The productivity of winter forage crops was evaluated from mid to late May 2012 by directly collecting information from farmhouses. A survey of winter forage crop productivity was conducted with 66 farmers in 16 regions; including, Italian ryegrass (IRG) from 22 farmers in 11 regions, whole crop barley from 21 farmers in eight regions, rye from 11 farmers in five regions, and IRG mixed with whole crop barley from 12 farmers in six regions. The results indicated that the Konju region exhibited higher yields of dry matter (DM) forage (15,128 kg/ha) and that the Dangjin region (reclaimed land) showed the lowest (3,885 kg/ha). The average yield of DM forage was 9,418 kg/ha. Yields of whole crop barley and IRG mixed with whole crop barley were comparatively higher than those of rye and IRG. We conclude that overall forage productivity was influenced by farmer's cultivation ability rather than the forage cultivation environment.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.300-300
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• 2017

'Saemimyeon' a Tongil-type rice variety (Indica ${\times}$ Japonica), which contains high amylose contents is suitable for rice noodle production. Nowadays, the major parts of rice processing industry that includes products like rice flour and noodles are expected to partially replace wheat flour market. The volume of rice noodle market is getting bigger and can contribute to the rice surplus and farmer's income. This study was carried out to promote productivity and flour-making quality of 'Saemimyeon' by finding the most suitable transplanting and harvesting times. The transplanting days used were May $10^{th}$, May $17^{th}$, May $24^{th}$, May $31^{th}$, June $7^{th}$ and June $14^{th}$ and the planting distance used was 30 x 12cm. In addition, harvesting time was determined by days after heading time (40, 45, 50, 55 and 60 days). The field experiment was conducted at the experimental field in Miryang (Southern plain area of Korea) from 2015 to 2016. Our results suggest that the optimum transplanting days were from May $24^{th}$ to May $31^{th}$ which resulted to an average yield of 748~751kg/10a. Interestingly, yield was sharply decreased below 700kg/10a before May $10^{th}$ and after June $7^{th}$. The average grain filling rate before May $31^{th}$ was more than 83% but it declined to 75% after June $7^{th}$. The average temperature ranges from heading time to harvesting time was $ 21\sim25^{\circ}C$ and the estimated optimal temperature was $23.4^{\circ}C$ which is similar to May $24^{th}$ by regression equation. We found that the optimal harvest time was 45~50 days after heading time. It is hypothesized that low temperature at seed maturation time caused the lower grain filling rate therefore 'Saemimyeon' need to be transplanted before May $31^{th}$ for higher productivity. We found no statistical variation in amylose contents among experimental plots (28.2~30.4%). We conclude that the productivity of 'Saemimyeon' highly depends on temperature that is critical for grain filling stage controlled by transplanting time.