• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.271-275
• /
• 2012

The average annual and winter ambient air temperatures in Korea have risen by $0.7^{\circ}C$ and $1.4^{\circ}C$, respectively, during the last 30 years. The continuous rise in temperature presents a challenge in growing certain horticultural crops. Chinese cabbage, one most important cool season crop, may well be used as a model to study the influence of climate change on plant growth, because it is more adversely affected by elevated temperatures than warm season crops. This study examined the influence of transplanting time, nitrogen fertilizer level and climate parameters, including air temperature and growing degree days (GDD), on the performance of a Chinese cabbage cultivar (Chunkwang) during the spring growing season to estimate crop yield under the unfavorable environmental conditions. The chinese cabbage plants were transplanted from Apr. 8 to May 13, 2011 when 3~4 leaves were occurred, at internals of 7 days and cultivated with 3 levels of nitrogen fertilization. The data from plants transplanted on Apr. 22 and 29, 2012 were used for the prediction of yield as affected by planting date and nitrogen fertilization for spring production. In our study, plant dry weight was higher when the seedlings were transplanted on 15th (168 g) than on 22nd (139 g) of April. There was no significant difference in the yield when plants were grown with different levels of nitrogen fertilizer. The values of correlation coefficient ($R^2$) between GDD and number of leaves, and between GDD and dry weight of the above-ground plant parts were 0.9818 and 0.9584, respectively. Nitrogen fertilizer did not provide a good correlation with the plant growth. Results of this study suggest that the GDD values can be used as a good indicator in predicting the top biomass yield of Chinese cabbage.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.324-324
• /
• 2017

Total 15 different corn hybrids, Kwangpyeongok, Gangdaok, Yanganok, Singwangok, Jangdaok, Cheonganok, Cheongdaok, Andaok, Dapyeongok, Pyeongkangok, Pyeonganok, Daanok, Sunwon P3394, Gangilok, P3394, had been used to investigate the plant growth and yield of corn hybrids depends on the sowing date. Sowing dates were April 5th, June 25th, and July 5th and all experiments had three repeats. The growth of Gangdaok was the best. However, in the case of Kwangpyeongok, the growth was not the best to compare with Gangdaok, but the stem to ear height ratio was lower than Gangdaok, it may be better for the stable cultivation. Both of the growth and yield of Daanok was not good regardless of planting date, but the yield and ear shape of Pyeongkangok and Dapyeongok were good for fresh corn. The growth and yield of 15 different corn hybrids were variable depends on the planting date, however, the growth degree days (GDD) was the most important factor for the maturity of the corn. More than $1500^{\circ}C$ of GDD was enough to harvest mature corn hybrids in the central region of Korea. Besides the yield and growth, other characters such as sweetness and taste as a food should be investigated further for the fresh corn to be suggested.

• Journal of Bio-Environment Control
• /
• v.31 no.4
• /
• pp.432-437
• /
• 2022

In this study, strawberries were grown during the two cultivation periods (first: 2020-2021, second: 2021-2022) to analyze the effect of the external light environment and growing degree days (GDD) on crop production. The temperature and humidity during day in a greenhouse in each cultivation period were similarly managed. At night, there was a statistical difference in temperature and humidity in the greenhouse between two periods. The accumulated solar radiation during the first cultivation period was high in September and October. Since January, the accumulated solar radiation during the second cultivation period was high. In the second cultivation period, the initial yield was small because the accumulated solar radiation and GDD was small. But accumulated yields and potential maximum yields in second cultivation period were larger than yields in the first cultivation period as the accumulated solar radiation and GDD increased. The sugar contents of strawberry decreased as GDD increased.

• Journal of Climate Change Research
• /
• v.7 no.4
• /
• pp.493-498
• /
• 2016

This study was conducted to investigate the effect of environment factors on full bloom stage and fruit width in four peach cultivars. The average temperature in March was the main factor to determine the date of full bloom in 'Kurakatawase'($-0.6871^*$) and 'Changhowon Hwangdo'($-0.5270^*$). The fruit growth curve after 35 days from full bloom was the double sigmoid shape in 'Changhowon Hwangdo' cultivar. Environmental factors affecting fruit width were mean diurnal range(BIO2) and temperature annual range(BIO 7) in 'Kurakatawase', growing degree days(GDD) after 30 days from full bloom and July precipitation in 'Yumyeong', and annual mean temperature(BIO1), BIO7, and July precipitation in 'Kawanakajima Hakuto'. Of these, major environmental factors affecting fruit width in more than two cultivars were BIO7 and July precipitation.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.16 no.4
• /
• pp.291-298
• /
• 1996

This study was carried out at Crop Experiment Station in 1993 and 1994. The objective of this study was finding out variation of growth and yield of corn according to maturity. Hybrids of corn used in this study were early maturing corn Comet80, Elite90, Royaldent IOOT, Royaldent T$\times$llO, P3525, P3394, medium maturing corn Royaldent 120T. and late maturing corn Jungbuok, P3144W. G4743. Stalk height, leaf number, ear weight, stover weight, and TDN yield of early maturing corn were linearly increased with prolonged maturity in 1993 growing season. Leaf number, and stover weight of early and late maturing corn were linearly increased with prolonged maturity in 1994 growing season. But ear weight of late manuring corn was not increased as much as that of early manuring corn with prolonged maturity. Increase of total DM and TDN yield of late maturing corn was due to stover weight increase compared with ear weight increase of early maturing corn. Leaf number and stover weight were highly correlated with silk (Growing Degree Days) GDD.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_2
• /
• pp.641-645
• /
• 2017

This study was conducted to compare three agro-climatic indices among 22 agro-climatic zones in Northeast China area. Meteorological data produced by NASA (MERRA-2) was used to calculate growing degree days (GDD), frost free period (FFP), and growth season length (GSL) at this study sites. The three indices did not differ among 6 years (2011-2016). However, they showed statistical spatial difference among agro-climatic zones. The GDD ranged between $531.7^{\circ}C{\cdot}day$ (zone 22) and $1650.6^{\circ}C{\cdot}day$ (zone 1). The range of the FFP was from 141.5 day (zone 22) to 241.7 day (zone 1). And the GSL showed spatial distribution between 125.1 day (zone 22) and 217.9 day (zone 1).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.28 no.4
• /
• pp.481-487
• /
• 1983

The need to synchronize flowering in two lines of different maturities is frequently encountered in hybrid com (Zea mays L.) seed production. To establish the methods for synchrony of flowering in parent lines of different maturities be effects of clipping at 4 and 6-leaf stages of growth and two levels, clear polyethylene mulching and five different planting dates on flowering date growth and seed yield of two dent com inbred lines of different maturities were evaluated Clipping just above the shoot-apex delayed pollen sheeding 6 to 9days and silking 5 to 13 days but reduced stand and seed yield 30 to 70% and 67 to 81%. respectively. Clipping 5cm above the shoot apex delayed flowering 1 to 4 days without stand reduction but reduced yield 3 to 29%. Laterclipping was slightly more effective for delaying flowering than earlier clipping but reduced stand more severely when clipped just above the shoot apex. Under clear polyethylene film mulching, flowering of two lines was 13 to 15 days earlier and seed yield of B68 (late line) was significantly increased. As planting was delayed from April 18 to June 13, the number of days from planting to flowering of two lines decreased due to increase in air temperature. However, growing degree days (GDD) from planting to flowering of each lines was similar regardless planting dates indicating that GDD can be satisfactoryly used for choosing the planting dates of parent lines of different maturities. Seed yields of two lines were decreased with delaying planting dates.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_1
• /
• pp.1199-1206
• /
• 2021

Accordingly, attention is also being paid to the agricultural use of remote sensing technique that non-destructively and continuously detects the growth and physiological status of crops. However, when remote sensing techniques are used for crop monitoring, it is possible to continuously monitor the abnormality of crops in real time. For this, standard growth information of crops is required and relative growth considering the cultivation environment must be identified. With the relationship between GDD (Growing Degree Days), which is the cumulative temperature related to crop growth obtained from ideal cultivation management, and the vegetation index as standard growth information, compared with the vegetation index observed with the spectralreflectance sensor(SRS_NDVI & SRS_PRI) in each rice paddy treated with standard cultivation management and non-fertilized, it was quantitatively identified as a time series. In the future, it is necessary to accumulate a database targeting various climatic conditions and varieties in the standard cultivation management area to establish a more reliable standard growth information.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.35 no.3
• /
• pp.254-258
• /
• 1990

In order to investigate the effect of sowing dates on some agronomical characters and yield of corn in southern part of Korea. a field experiment was carried out at Gyeongnam Provincial Livestock Breeding Station in chinju. Single cross hybrid corn (cv. Suwon #19) was sown from April 13 to June 2 with five-day interval in 1984 and 1984. The relationship between herbage and grain yield and various meterological measurements was evaluated. As the sowing dates were delayed. the days from sowing to seedling emergence were shortened, as more closely affected by the soil temperature at seedling emergence. growth period and was dependent on precipitation and temperature during the growth period. Based on the relationship between herbege dry matter yield of corn and soil temperature at seedling emergence, the estimated critical sowing date for corn in the southern Korea was March 23${\pm}$3.6 days.

• Journal of Bio-Environment Control
• /
• v.32 no.4
• /
• pp.366-376
• /
• 2023

This study was conducted to develop a model for predicting the growth of kimchi cabbage using image data and environmental data. Kimchi cabbages of the 'Cheongmyeong Gaual' variety were planted three times on July 11th, July 19th, and July 27th at a test field located at Pyeongchang-gun, Gangwon-do (37°37' N 128°32' E, 510 elevation), and data on growth, images, and environmental conditions were collected until September 12th. To select key factors for the kimchi cabbage growth prediction model, a correlation analysis was conducted using the collected growth data and meteorological data. The correlation coefficient between fresh weight and growth degree days (GDD) and between fresh weight and integrated solar radiation showed a high correlation coefficient of 0.88. Additionally, fresh weight had significant correlations with height and leaf area of kimchi cabbages, with correlation coefficients of 0.78 and 0.79, respectively. Canopy coverage was selected from the image data and GDD was selected from the environmental data based on references from previous researches. A prediction model for kimchi cabbage of biomass, leaf count, and leaf area was developed by combining GDD, canopy coverage and growth data. Single-factor models, including quadratic, sigmoid, and logistic models, were created and the sigmoid prediction model showed the best explanatory power according to the evaluation results. Developing a multi-factor growth prediction model by combining GDD and canopy coverage resulted in improved determination coefficients of 0.9, 0.95, and 0.89 for biomass, leaf count, and leaf area, respectively, compared to single-factor prediction models. To validate the developed model, validation was conducted and the determination coefficient between measured and predicted fresh weight was 0.91, with an RMSE of 134.2 g, indicating high prediction accuracy. In the past, kimchi cabbage growth prediction was often based on meteorological or image data, which resulted in low predictive accuracy due to the inability to reflect on-site conditions or the heading up of kimchi cabbage. Combining these two prediction methods is expected to enhance the accuracy of crop yield predictions by compensating for the weaknesses of each observation method.