• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.1
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• pp.61-69
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• 2024

Considering the threats of climate change, this study was conducted to investigate the influence of temperature and day-length on soybean growth and yield when sown late in comparison to the optimal sowing time in the southern region of the Korean Peninsula. Sowing was executed in 10-day intervals, including on July 1, 10, 20 and 30 and August 10, considering that the optimum sowing time of the three soybean varieties with different ecotypes is June 20. Emergence rates did not differ significantly between late-sowing and optimal sowing in all ecotypes; however, the number of days to emergence, flowering, and maturity was smaller after late sowing. A multiple-regression approach was used to test the effect of temperature and day length on the number of growing days after late sowing compared to the optimal sowing time. This analysis revealed that the number of days required from sowing to flowering was positively correlated with both day length and temperature, and the number of days from flowering to harvest was positively correlated with day length and negatively with temperature. A multiple regression equation can be calculated as follows: the number of days required from sowing to flowering (Y) = 3.177 + (0.030 × (sum of day length + sum of temperature)), and the number of days required from flowering to maturity (Y) = 20.945 + (0.021 × (sum of day length + sum of temperature)). Multiple growth parameters were significantly correlated with yield components, depending on growing days. Optimal sowing resulted in the best yield, while later sowing decreased yield compared to optimal sowing. To avoid a significant decrease in yield, early-maturing species should be sown by July 20, while late-maturing species should be sown by July 10.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.113-117
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• 2006

To identity the effect of sowing dates on flowering and maturity of sesame, some agronomic traits including days to flowering and days to maturity were investigated under five different sowing dates. Plant height, days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant were showed significantly different by years, sowing dates and varieties. Interaction between sowing dates and varieties affected to days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant. Plant height, days to flowering and days to maturity decreased significantly as sowing dates were delayed, but number of capsules and seed weight per plant showed highest at the sowing date of May 10. At the regression analysis of shortness degree of growth period by the response of days to flowering and days to maturity under different sowing dates, sesame varieties with earlier flowering habit were much less affected by day length rather than ones with later flowering habit. $R^2$ and gradient value on the days to maturity regression graph were smaller indicating that maturity was much less sensitivity than flowering to the change of day length and temperature in the move of sowing dates. Therefore, it would be concluded that early maturity sesame varieties have higher potential adaptability to various sesame cropping systems in view of their less sensitivity to day length changes under different sowing dates.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.241-247
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• 2020

Sesame is typically a temperature- and day length-sensitive plant, as its flowering is promoted under high temperature and shorter day length conditions. The experiment carried out in the present study revealed that day length influenced sesame flowering to a much greater extent than temperature. The degree of day length influence differed depending on the sesame variety. Days from sowing to flowering was negatively correlated with yield-related characteristics such as stem length, capsule number per plant, 1,000 seed weight, and seed weight per 10a. In cases where the period from sowing to flowering was longer and flowering date was later, the reproductive growth period was shorter during maturity. Analysis of the effects of temperature and day length on seed yield production revealed that temperature was a much more influential factor than day length. However, day length was more influential than temperature under low temperatures, such as 22℃. All varieties apart from Ansan were shown to be primarily influenced by temperature. Sesame varieties were grouped in view of optimal seed sowing time through principal components analysis. The Poongsung and Sungboon varieties favored early sowing under low temperatures and short day lengths. The DT45, Poongsung, 90 days, Ansan, and Sungboon varieties favored late sowing under high temperatures and long day lengths. The Yangbaek and Arum varieties could be sown both early and late.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.188-198
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• 2016

In soybeans, responses of high temperature according to shift of sowing dates during the growing season was explored using the crop model, CROPGRO-soybean. In addition, it analyzed impact on change of sowing dates affects yield potential of soybean under future climate scenario (2041-2070). In Jeonju and Miryang during 1981-2010, if sowing at 15 or ten days ahead from 10 June, namely in shorten of the sowing day (i.e. when sown on 25 or 30 May), the yield potential reduced. However, the yield potential increased when sown 5 June. In the case of delay of sowing day (i.e. when sown on 15 or 20 June), reduction of yield potential in the average -5% was higher than increase in the average +2%. In particular, the relative changes for shorten of the sowing day or delay of the sowing day do not be shown in normal years which high temperatures did not abnormally occur during the growing season from 2003 to 2010 except when sown on 25 May. In abnormal years which high temperatures occurred during the critical period, especially R5 to R7, shorten of the sowing day affected to the increase of yield potential in Miryang, while the yield potential decreased in Jeonju except when sown on 5 June. However, delay of the sowing day influenced on the reduction of yield potential both in two sites. In future climate scenario of Representative Concentration Pathway (RCP) 8.5 during from 2041 to 2070, the increase and decrease of yield potential for shorten of the sowing day were +10/-9% for RCP 8.5 of Jeonju, and +14/-9% for RCP 8.5 of Miryang, respectively. Additionally, it showed +10/-17% for RCP 8.5 in Jeonju, and +10/-29% for RCP 8.5 in Miryang, respectively in the increase and decrease of yield potential for delay of the sowing day.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.433-440
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• 2005

Four varieties of perilla(Perilla ocimoids L.) were tested to investigate the ecological adaptation of the crop to variations in sowing time extending from April 25 to July 25 with an interval of 30 days between each of the four sowing. As sowing time was delayed, the plant height, the number of first branches and cluster, the weight of fresh and dried stems, the day to germination and flowering decreased, showing a highly negative correlation between the showing dates and these characteristics, but a highly positive correlation between days to flowering and the required accumulated temperature. With early sowing under low temperature and long day conditions, it took about 132 days from sowing to flowering due to the long period of vegetative growth, but as sowing was delayed, the days to flowering decreased with a minimum period of 57 days. The yield of seeds in each case varied with each variety. Type A(Nonsan var.) and type B(Jinchon var.) had higher yields when sowed earlier. But type C(Namyang var. and Wooljin var.) had its highest yield in the plot sowed on May 25 and the 1000 grain weight showed a tendency to increase as sowing was delayed. In conclusion, the perilla was preyed to be a short-day plant that flowers from the begining to the middle of Sep. regardless of sowing time, so that the sowing time should be decided after due consideration of the length of the vegetative growth periods of the varieties.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.130-134
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• 1984

This experiment was conducted to know critical sowing depth and emergence day under different sowing depth at Crop Experiment Station, Suweon, in 1982. Tested weed species were Sagittaria pygnaea, Eleocharis kuroguwai, Cyperus serotinus and Potamageton distinetus, sowing depth of weeds were 5cm, 10cm, 15cm, 20cm and 25cm Critical emergence sowing depth of S. pygnaea, E. kuroguwai was 15cmand C. serotinus was 20cm sowing depth while P. distintus was 25cm sowing depth. Average emergence days under 5cm sowing depth for E. kurogwai, S. pygmaea, P. distintus and C. serotinus was 27.8 days, 14.1 days, 13.6 days and 7.3 days. While, relationships between sowing depth and day to emergence was positively correlated. Gernination percent of weeds under Critical emergence sowing depth, S. pygmaea, E. kurogwai and, P. distinctus was 57%, 67%, 80%, but C. serotinu.s was all died.

• Current Research on Agriculture and Life Sciences
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• v.18
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• pp.53-60
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• 2000

Seedling characteristics of rice sowed at different sowing date in an automatic facility were studied at different days after sowing (DAS). The objective was to determine the optimum sowing date and age of rice seedlings at three locations in the Kyongbuk Province of Korea viz, Andong, Euisung and Kyongsan. Heigbt and shoot dry weight of rice seedlings increased from 10 to 20 DAS and with a delay in sowing time from April to June. In these intervals shoot dry weight-height ratio decreased. For rice seeded in the last ten days of April, optimum seedling characteristics were attained between 15 to 20 DAS at Andong and Euisong and 15 DAS at Kyongsan. At the three locations, 10-day-seedlings exhibited superior characteristics to 15- and 20-day-seedlings for rice seeded in May and June. Rice seedlings of different ages were transplanted at a paddy field to determine the effect of seedling age on yield potential. The mean yield of 10-day-seedlings was 5% higher than that of 35-day-seedlings raised by the conventional method. The yield of 20-day-seedlings was 9% lower than that of 35-day-seedlings. Varietal differences in seedling characteristics of 13 rice cultivars were evaluated for the seedlings seeded in the automatic facility on June. Ten-day old seedlings ranged in height from 13.3 to 17.5 cm and shoot dry weight from 7.7 to 9.4 mg. Two cultivars, Daesanbyeo and Hwayeongbyeo, exhibited superior seedling traits compared to the remaining 11 cultivars and were, therefore, better adapted to the automatic seedling-raising facility.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.268-268
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• 2017

Common sowing method of italian ryegrass (IRG) has been using the backpack seed sprayer (BSS) in Korea. It has weak point including a hard work and a little sowing area. This study was conducted to find out the effects of sowing IRG using unmanned helicopter (UH) under the established rice field. We checked the labour saving of sowing IRG and the growth and yield of rice after using IRG as forage crop. Two sowing implements(using by UH and backpack seed sprayer (BSS)) were tested for the ability of sowing IRG. For proper pretreatment of IRG seeds for aerial sowing using with UH, we tested one-day soaking seeds, iron-coated seeds, coated seeds sold in stores and untreated seeds. Aerial sowing of IRG seeds using UH was tested under the speed 10 km/h and flying altitude 3~4m. We tried to confirm the effects on rice growth in a paddy field after IRG had been used as forage in mid May. In 6 hours of seeding per day, UH had a seeding area of 21.8 hectares, three times wider than BSS. UH had a decrease of about 63 percent of sowing-seed cost in comparison with BSS. In the IRG aerial sowing using UH, coating seeds had the wider sowing width of 5~6 meter than 3~4 meter untreated seeds. Residual dry matter of IRG after using forage had 4.5 ton per hectare and 20 percent of top dry matter. The amount of nitrogen remaining in residual IRG in the soil was 12 kg per hectare, and the other nutrients such as calcium and potassium was incorporated into the soil with less than 10 kg/ha. The rice yield after the harvesting IRG was 5 percent higher than that of rice single cropping. Consequently, IRG sowing using UH was effective in reducing sowing time and sowing cost compared with conventional methods and, it is considered that there is a positive effect on the rice cultivation compared to rice single cropping.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.137-142
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• 1991

For the constitution of forage cropping system including the double-cropping of corn, attention has been directed towards the early and short maturing varieties of corn such as Comet 80, Comet 85 and Linda as a component forage crop of forage cropping system. Four corn varieties, Comet 80, Comet 85, Linda and Suwon 19 were planted delayedly by each of 45, 55 and 65 days from the recommended sowing date of suwon 19. Under these condition, growth characteristics and late-sowing adaptability of 4 corn varieties were investigated, and the results are summarized as follows; 1. The variety of suwon 19 did not reach the stage of silking in the occasion of late sowing by 50 days from the optimum sowing time for mono cropping of suwon 19. However early varieties such as Comet 80, Comet 85 and Linda silked under the condition of 65 days-delayed sowing from the recommended sowing time of Suwon 19 for mono-cropping. 2. Early varieties of Comet 80, Comet 85 and Linda were so grown by approximately 92% in plant height, 66% in ear height, 88% in stem diameter and 81% in leaf number respectively compared to Suwon 19 at each of three delayed sowing time that exhibited the dwarfish appearance of canopy. 3. Days from sowing to silking decreased as the sowing time was delayed and the average days from sowing to silking in the sowing treatments of 55 days-delayed of Suwon 19, Comet 80, Comet 85 and Linda were 61, 46, 47 and 51 days, respectively. 4. The size of variations of plant height and ear height influenced by delayed-sowing time was comparatively larger in the varieties of Suwon 19 and Linda than in those of Comet 80 and Comet 85. 5. As sowing time was delayed from the optimum sowing time of Suwon 19 for mono-cropping, ear content decreased from 0% of Suwon 19 at 55 day-delayed sowing treatment to 3540% of Comet 80 and Comet 85 at 65 days-delayed sowing treatment.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.3
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• pp.169-175
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• 2022

This study aimed to examine the changes in dry matter yield and growth characteristics of alfalfa (Medicago sativa L.) in response to variations in sowing dates during the autumn season of 2021-22 in a dry paddy field of Chilbo-myeon, Jeongeup-si, Jeollabuk-do. Treatments comprised four sowing dates at 10-day intervals, i.e., October 8, October 18, October 28, and November 8, 2021. The winter survival rate of alfalfa showed a significant difference between different treatments but was at a satisfactory level for all (p<0.05). The winter survival rate for the fourth sowing date, a month later than the first sowing date, was approximately 11.7% lower than that for the first sowing date. The plant height ranged between 82.3-93.1 cm and 60.5-63.7 cm at the first and second harvest, respectively, smaller at the second harvest than at the first harvest. The total dry matter yield of alfalfa was the highest at 13,316 kg/ha for the first sowing date, and the later the sowing date, the lower the dry matter yield. The protein content of alfalfa ranged between 13.6-17.3% in the first harvest, lower than the standard alfalfa protein content of 20% or more. In relative feed value, the first sowing (Oct. 8) was the most significantly higher in the first harvest (p<0.05). These results suggest that the early and mid-October sowing dates are optimum for sowing alfalfa during autumn and result in improved plant growth, dry matter yield, protein content, and winter survival compared to those at later sowing dates. Therefore, dry paddy fields can be safely employed for alfalfa cultivation with sowing dates in early and mid-October during autumn.