• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.421-426
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• 2013

This study was conducted to investigate the effects of timing of nutrient starvation during transplant production on growth of runner plants and yield of strawberry 'Seolhyang' (Fragaria ${\times}$ ananassa). Nutrient solution supply at the level of EC (electrical conductivity) 0.8 $dS{\cdot}m^{-1}$ was terminated at interval about 10 days between July 25 and September 5. As a result, the growth of above-ground part was inhibited while root growth increased when the nutrient starvation treatment had been brought forward to July 25. It also reduced the T/R ratio significantly and chlorophyll content was tended to be lower than the other treatment. In addition, it significantly promoted the budding, flowering and harvest of first flower cluster. On the other hand, the period of harvest was delayed more than two weeks when the nutrients were continuously supplied after the middle of August. An accumulated marketable fruit yield per plant until the end of January and February was 169 and 266g, respectively in the treatment of nutrient starvation on July 25, which was 71 and 12% increase, respectively, as compared with those in the treatment of September 5. Therefore, the appropriate nutrient starvation in the late season of strawberry nursery period could be expected the increase in yield and income during the winter season by promoting the flower bud differentiation as reducing the endogenous nitrate level of the plantlet.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.161-169
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• 2005

With various Korean domestic soybeans, growth and yields analysis were conducted to select the suitable soybean cultivars for cultivation in paddy field. Distinctive aspects of the soybean growth were observed in paddy field such as retarded growth of top plants and roots, relatively higher T/R ratio followed by overgrowth of top plant. However, growth and yields were significantly different among the cultivars showing 134kg/10a in Paldokong and 385 kg/10a in Doremikong. At V5. and R2 stage, highly positive correlations $(r=0.76^{**}\~0.91^{**})$ were observed between leaf area and dry weight of top plant and/or root. T/R ratio was negatively correlated with dry weight of root $(r=-0.37^*)$ at V5 stage, while significantly correlated with leaf area $(r=-0.37^{**})$ and dry weight of top plant $(r=0.65^{**})$at R2 stage. Among the characters, only 100-seed weight was significantly correlated with yield. Considering the growth characters, 37 cultivars could be included in 3 different groups and genotypic properties such as maturity and growth habit were similar in each group. Nine cultivars in group 1 showed retarded growth from V5 to R2 stage, relatively lower T/R ratio, and good seed ripening. Average yields of the cultivers was 257kg/10a. In group 2, 12 cultivars showed higher T/R ratio due to overgrowth of top plant and lowest average yields (230 kg/l0a) due to poor seed ripening. Sixteen cultivars in group 3 grew fast from V5 to R2 stage representing late maturity traits, low T/R ratio, and good seed ripening. Average yields of the cultivars was highest among groups showing 270kg/l0a. In results, stable self-sufficiency of soybean yields could be expected by selective cultivation with high yielding cultivars ranging from 301 to 385kg/10a, such as Shinpaldalkong 2, Sohokong, Doremikong, Keumkangkong, Bukangkong, Dajangkong, and Geomjeongkong 2, or with cultivars included in group 3.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.325-331
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• 2014

The purpose of this study was to establish the proper sowing time and planting density of cowpeas for labor-saving cultivation. Experiments were carried out in Naju, Jeonnam Province (Latitude $35^{\circ}$ 04' N, Longitude $126^{\circ}$ 54' E) during 2012 and 2013. The intermediate-erect type strains used in this study were Jeonnam1 and Jeonnam2. Sowing was performed five times between June 25 and August 5 at approximately 10-day intervals in order to establish proper sowing time, and sowed at 5,000, 10,000, 15,000, and 20,000 plants per 10a to establish proper planting density. The days from sowing to first flowering was shortest (32 days) in plants sowed on July 25 and became longer for plants sowed on or around July 25. The days from sowing to first flowering was longest (41 days) in plants sowed on June 25. The days from first flowering to first maturing was shortest (8 days) in plants sowed on June 25 and, became considerably longer at later sowing dates. The days from first maturing to first harvesting ranged from 8 to 10 days, with little difference among the sowing periods. Plants sowed on August 5 harvested at the same time, and plants sowed between June 25 and July 25 were harvested either three or two times. The yield was highest in plants sowed on July 25: 209 kg/10a was harvested for Jeonnam1 and 221 kg/10a for Jeonnam2. Furthermore, harvested at the same time enabled when the harvesting was delayed for around 15 days because the share of the seeds first harvested was highest (91%). The proper planting density was estimated to be 15,000 plants/10a, showing the highest yields of 199 kg/10a for Jeonnam1 and 224 kg/10a for Jeonnam2.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.666-676
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• 2013

The study was carried out to examine the initial point of dormancy, breaking time of internal dormancy, and to find out the accumulated hours of low temperature (under $7.2^{\circ}C$ from $0.0^{\circ}C$ to $7.2^{\circ}C$) for bud-breaking. Over-all, the chilling requirement for breaking of internal dormancy in the commercial apple cultivars ('Fuji' and 'Tsugaru') and apple cultivars bred in Korea ('Hongro', 'Sunhong', 'Honggeum', 'Hongan', 'Hongso', 'Gamhong', 'Summer dream') at the Gunwi region for 4 years (from 2009 to 2012) was investigated. Also, the breaking time of internal dormancy in the field at the Gunwi region and the breaking time of dormancy if air temperature of Gunwi region rises $4^{\circ}C$ higher than the current one were investigated using the same data. The initial point of dormancy was set at the time when the lateral bud breaking did not occurred (when heading back cutting was done in the middle of terminal shoots). The occurrence of the breaking of internal dormancy was decided if the breaking of the terminal bud of bourse shoot occurred within 15 days or not in growth chamber. About 100 bourse shoots were collected by cultivar classification in early December every year and were stored at $5.0^{\circ}C$, and they were placed in growth chamber at one week interval. The chilling requirement of cultivars was expressed in accumulated hours in the field and in the growth chamber under $7.2^{\circ}C$ and $0.0-7.2^{\circ}C$ from the initial point of dormancy to the breaking time of internal dormancy. The results showed that the initial point of dormancy in selected cultivars could occur at the end of September. The breaking time of internal dormancy could occur from the end of January to the early of February. The accumulated hours under $7.2^{\circ}C$ for breaking of internal dormancy were 1,600-2,000 hours, while those of $0.0-7.2^{\circ}C$ were 1,300-1,800 hours. In comparing the different apple cultivars, the chilling requirement of the early flowering cultivars seemed lower than that of the late-flowering cultivars. Based on these results, if the air temperature of Gunwi region rises about $4.0^{\circ}C$ higher than the current one, the breaking time of internal dormancy will be delayed by 2-4 weeks.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.245-252
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• 2018

Yam bean (Pachyrhizus erosus) is a subtropical plant belonging to the Fabaceae family, and is a tuberous vegetable used as various food material with a crisp and juicy taste. This study was conducted to seek optimum sowing time of yam bean in Korea. For this, we surveyed germination properties by the different temperatures and compared the accumulation temperature (AT) and dry matter production (DMP) on growth stages of yam bean by the different sowing times. Two types of varieties cultivated mainly in Korea, Thailand local variety (TLV) and Cheongunmanma cultivar (CGMM), was used. The germination rate of yam bean was 86.0~94.0% at above $18^{\circ}C$, and germination days was longer at lower temperature. The times for flowering and tuber formation of CGMM were later than those of TLV, and the AT required for flowering, tuber formation and hypertrophy of CGMM were higher than those of TLV by $293^{\circ}C$, $280^{\circ}C$ and $108^{\circ}C$, respectively. Also, DMP of shoot and tuber in CGMM were greater than those in TLV. In sowing at April 25, tuber formation was slower than sowing after that time, and harvest index (HI) was relatively low due to delayed formation and hypertrophy of tuber. In sowing after June 9, DMP of shoot was relatively greater in early growth, but tuber was not sufficient to enlarge due to lack of growth days by cold and frost in late October. In sowing May 10 and 25, DMP of tuber and HI were the highest, because the change of day length and temperature gave an advantage to vegetable growth and tuber development. All above suggest that it was suitable to sow seeds on May for increment of tuber productivity in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.92-97
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• 1995

The objective of this study is to investigate the growth characters of overhead flooded soybean plants at four growth stage. Overhead flooding treatments were applied at the vegetative growth stage ($V_3,\;V_6$) and the reproductive stage ($R_2,\;R_4$) for 6.12.24 hrs, respectively. Yield and yield components were more decreased as the overhead flooding duration was longer and the growth stage was later. Yield was not reduced significantly in soybean plants flooded at $V_3$ stage regardless of flooding duration, and flooded 6 or 12 hrs at $V_6$ stage. When compared to the control, 27 to 36% of yield reduction was observed in soybean plants flooded for 24 hrs at $V_6$ stage, 6 or 12 hrs at $R_2$ stage, and 6 hrs at $R_4$ stage. And 43%, 53% and 66% of yield were reduced through the flooding treatment for 24 hrs at $R_2$ stage 12 hrs and 24 hrs at $R_4$ stage, respectively. So yield reduction was higher in overhead flooded soybean plants at the reproductive stage than that at the vegetative growth stage.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.1
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• pp.1-8
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• 2007

This experiment was conducted to determine the effect of growth stage and variety on the yield and quality of whole crop rice (WCR) at National Livestock Research Institute, RDA from 2003 to 2005. Two types of rice ("Chucheong" for food and "Hamasari" for feed) were harvested at six different growth stages (heading, flowering, milk, dough, yellow ripening and fully ripening stage). Crude protein content decreased with progressed maturity at harvest. As growth stage delayed, TDN (total digestible nutrient) content of all rice varieties increased. The average TDN content of two type of rice was about 60% (59.3) which was calculated from ADF(acid detergent fiber) content. The contents of ADF and NDF(neutral detergent fiber) decreased with harvest maturity. The highest DM(dry matter) yield was at the ripening stage (p<0.05) and "Chucheong" gave higher yields than for "Hamasari". In this experiment, the DM yield of all varieties was low. The yield of TDN followed a similar trend to DM yield. According to this results that dough to yellow ripening stage of harvest maturity will be recommendable as proper harvest time for whole crop rice silage.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.151-160
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• 2018

Anoplophora chinensis and A. glabripennis is classified as important quarantine Cerambycidae beetles worldwide. These beetles cause serious damage on natural host plants and export bonsai trees in Korea. We evaluated efficacy of phosphine fumigant for control of two Cerambycidae beetles in bonsai. In the preliminary test to achieve CT (Concentration x time) values of phosphine to Cerambyicdae beetles larvae, we used Monochamus alternatus of larvae as an alternative insect. A 24 h phosphine fumigation with $2g/m^3$ phophine achieved 100% eggs mortality against Anoplophora chinensis and A. glabripennis. Larva of A. chinensis was also completely controlled when treated for 168-h at same dose desiccator. 100% mortality on larval stage of two beetle species were achieved both in dormancy (January) and vegetative period (February) of bonsai when treated with $2g/m^3$ phosphine. However, phosphine fumigation against vegetative period of Acer palmatum, Carpinus turczaninowii and Malus sieboldii bonsai showed slight phytotoxicity (shorten leaf and flower size and delayed flowering).

• Horticultural Science & Technology
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• v.32 no.4
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• pp.507-516
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• 2014

The present study was conducted to determine the effect of electron beam irradiation on control of Botrytis cinerea and postharvest quality of cut roses. Electron beam doses of 0.1, 0.2, 0.4, 0.6, 0.8, 1, 2, 10, and 20 kGy were applied with a 10-MeV linear electron beam accelerator (EB Tech, Korea). Electron beams inhibited spore germination and mycelial growth of B. cinerea with increasing irradiation doses. Conidia of B. cinerea were more tolerant to irradiation than were mycelia: the effective irradiation doses for 50% inhibition ($ED_{50}$) of spore germination and mycelial growth were 2.02 kGy and 0.89 kGy, respectively. In addition, electron beam irradiation was more effective in reducing mycelial growth of B. cinerea at $10^{\circ}C$ than at $20^{\circ}C$. Analysis of in vivo antifungal activity revealed that elevated irradiation doses exhibited increased control efficacy for tomato gray mold. Flower longevity and fresh weight of cut roses decreased when the irradiation dose was increased. In addition, flower bud opening tended to be inhibited in a dose-dependent manner. Although 'Decoration', 'Il se Bronze', 'Queen Bee', and 'Revue' roses tolerated and maintained overall postharvest quality up to 0.4 kGy, 'Vivian' did not, demonstrating that the irradiation sensitivity of cut roses varies according to cultivar.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.317-322
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• 1987

In order to find out the optimum transplanting date of mat rush, this study was investigated ecological characters, yield components and yield of three varieties (Okayama#2, Sajanami and Sedo #4) at 5 transplanting dates(October 25, November 5, November 15, November 25 and March 5). As transplanting date was delayed, the flowering date and maturing date was delayed also and stem length was longest in October 25 transplanting but it grew short in the late transplanting. Number of stems per plant was increased most in October 25 transplanting, that is, increased to 143 in okayama#2, 138 in Sedo#4 and 135 in Sajanami, and it was decreased in the late transplanting. Fresh stem yield and dry stem yield were heaviest in October 25 transplanting, and it was light in the late transplanting. Judging from the results reported above, in optimum transplanting date of mat rush seemed to be before the October 25.