• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.3
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• pp.209-218
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• 2007

This experiment was conducted to investigate effect of plowing frequency and sowing dates on the agronomic characteristics, feed value, weed yield and palatability of silage corn. Treatments were a basal treatment(C: May 5 seeding, plowing once, weeding control once), T1(May 12 seeding, plowing twice, weeding control 0 time), T2(May 19 seeding, plowing three times, weeding control 0 time, T3(May 26 seeding, plowing four times, weeding control 0 time) and T4(June 2 seeding, plowing five times, weeding control 0 time). The experiment was performed at the College of Life and Natural Sciences of Sangju University in Sangju in 2006. The plant height and ear height showed highly in order to C > T1 > T2 > T3 > T4 treatment, leaf length was the highest at T2 (96.0cm). Leaf width and number of dead leaf were the highest at C and T3 (11.2cm), C, C and T1 (4.6), respectively. Stem diameter was the highest at T3 as 31mm, while T2 was the lowest as 25mm (p<0.05). Ear circle showed highly in order of C > T1 > T4 > T3 > T4 (p<0.05), and tip filling degree was the highest at C treatment as 8.8, while T4 treatment was the lowest as 6.0 (p<0.05). The stem hardness and grain hardness were C < T1 < T2 < T3 < T4 (p<0.05). Stem saccharinity was T1(6.1%) was the highest, while T2(3.0%) was the lowest(P<0.05). Fresh yield of weed was the lowest at C treatment as 500 kg/ha, but T1 treatment was the highest as 44,100 kg/ha (p<0.05). Weed coverage rate showed highly in order of T1 > T2 > T3 > T4 > C treatment (p<0.05). Fresh yield of corn was the highest at C treatment as T3,550 kg/ha, but T4 treatment was the lowest as 65,500 kg/ha (p<0.05). Dry matter yield of corn showed highly in order of C(26,978 kg/ha) > T1(26,130 kg/ha) > T2(20,255 kg/ha) > T3(20,255 kg/ha) > T4(17,508 kg/ha) treatment (p<0.05). Crude protein content was T1(7.69%) > T4(7.42%) > T2(6.34%) > T3(5.99%) > C(5.91%) treatment (p<0.05), and Crude fat content showed highly in order of C (2.13%) > T1(2.04%) > T2(1.96%) > T3(1.95%) > T4(1.84%) treatment. Relative palatability of Holstein, Korean native goat and spotted deer was the highest at C treatment, but Korean native cattle was the highest at T1 treatment.

• Reproductive and Developmental Biology
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• v.28 no.1
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• pp.21-27
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• 2004

This study was conducted to investigate the developmental ability of caprine embryos after somatic cell interspecies nuclear transfer. Recipient bovine and porcine oocytes were obtained from slaughterhouse and were matured in vitro according to established protocols. Donor cells were obtained from an ear-skin biopsy of a caprine, digested with 0.25% trypsin-EDTA in PBS and primary fibroblast cultures were established in TCM-199 with 10% FBS. The matured oocytes were dipped in D-PBS plus 10% FBS ＋ 7.5 $\mu$ g/ml cytochalasin B and 0.05M sucrose. Enucleation were accomplished by aspirating the first polar body and partial cytoplasm which containing metaphase II chromosomes using a micropipette with an out diameter of 20∼30 $\mu$m. A Single donor cell was individually transferred into the perivitelline space of each enucleated oocyte. The reconstructed oocytes were electric fusion with 0.3M mannitol fusion medium. After the electrofusion, embryos were activated by electric stimulation. Interspecies nuclear transfer embryos with bovine cytoplasts were cultured in TCM-199 medium supplemented with 10% FBS including bovine oviduct epithelial cells for 7∼9 day. And porcine cytoplasts were cultured in NCSU-23 medium supplemented with 10% FBS for 6 ∼8 day at $39^{\circ}C, 5% CO_2 $in air. Interspecies nuclear transfer by recipient bovine oocytes were fused with electric length 1.95 kv/cm and 2.10 kv/cm. There was no significant difference between two electric length in fusion rate(47.7 and 44.6%) and in cleavage rate(41.9 and 54.5%). Using electric length 1.95 kv/cm and 2.10 kv/cm in caprine-porcine NT oocytes, there was also no significant difference between two treatments in fusion rate(51.3 and 46.1%) and in cleavage rate(75.0 and 84.9%). The caprine-bovine NT oocytes fusion rate was lower(P＜0.05) in 1 pulse for 60 $\mu$sec(19.3%), than those from 1 pulse for 30 $\mu$sec(50.8%) and 2 pulse for 30 $\mu$sec(31.0%). The cleavage rate was higher(P＜0.05) in 1 pulse for 30 $\mu$sec(53.3%) and 2 pulse for 30 $\mu$sec(50.0%), than in 1 pulse for 60 $\mu$sec(18.2%). The caprine-porcine NT oocytes fusion rate was 48.1% in 1 pulse for 30 $\mu$sec, 45.2% in 2 pulse for 30 $\mu$sec and 48.6% in 1 pulse for 60 $\mu$sec. The cleavage rate was higher(P＜0.05) in 1 pulse for 30 $\mu$sec(78.4%) and 1 pulse for 60 $\mu$sec(79.4%), than in 2 pulse for 30 $\mu$sec(53.6%). In caprine-bovine NT embryos, the developmental rate of morula and blastocyst stage embryos were 22.6% in interspecies nuclear transfer and 30.6% in parthenotes, which was no significant differed. The developmental rate of morula and blastocyst stage embryos with caprine-porcine NT embryos were lower(P＜0.05) in interspecies nuclear transfer(5.1%) than parthenotes(37.4%).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.3
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• pp.1-40
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• 1965

To measure variations in some of the important agronomic characteristics of rice varieties under shifting of seedling dates, this study has been carried out at the Paddy Crop Division of Crop Experiment Station(then Agricultural Experiment Station) in Suwon for the period of three years 1958 to 1960. The varieties used in this study were Kwansan, Suwon ＃82, Mojo, Paltal and Chokwang, which have the different agronomic characteristics such as earliness and plant type. Seeds of each variety were sown at 14 different dates in 10-day interval starting on March 2. The seedlings were grown on seed bed for 30, 40, 50, 60, 70 and 80 days, respectively. The results of this study are as follows: A. Heading dates. 1. As the seeding date was delayed, the heading dates was almost proportionally delayed. The degree of delay was higher in early varieties and lower in late varieties and the longer the seedling stage, the more delayed the heading date. 2. Number of days to heading was proportionally lessened as seeding was delayed in all the varieties but the magnitude varied depending upon variety. In other words, the required period for heading in case of late planting was much shortened in late variety compared with early one. Within a variety, the number of days to heading was less shortened as the seedling stage was prolonged. Early variety reached earlier than late variety to the marginal date for the maximum shortening of days to heading and the longer the seeding stage, the limitted date came earlier. There was a certain limit in seeding date for shortening of days to heading as seeding was delayed, and days to heading were rather prolonged due to cold weather when seeded later than that date. 3. In linear regression equation, Y=a+bx obtained from the seeding dates and the number of days to heading, the coefficient b(shortening rate of days to heading) was closely correlated with the average number of days to heading. That is, the period from seeding to heading was more shortened in late variety than early one as seeding was delayed. 4. To the extent that the seedling stage is not so long and there is a linear relationship between delay of seeding and shortening of days to heading, it might be possible to predict heading date of a rice variety to be sown any date by using the linear regression obtained from variation of heading dates under the various seeding dates of the same variety. 5. It was found out that there was a close correlation between the numbers of days to heading in ordinary culture and the other ones. When a rice variety was planted during the period from the late part of March to the middle of June and the seedling ages were within 30 to 50 days, it could be possible to estimate heading date of the variety under late or early culture with the related data of ordinary culture. B. Maturing date. 6. Within (he marginal date for maturation of rice variety, maturing date was proportionally delayed as heading was delayed. Of course, the degree of delay depended upon varieties and seedling ages. The average air temperature (Y) during the ripening period of rice variety was getting lower as the heading date. (X) was delayed. Though there was a difference among varieties, in general, a linear regression equation(y=25.53-0.182X) could be obtained as far as heading date were within August 1 to September 13. 7. Depending upon earliness of a rice variety, the average air temperature during the ripening period were greatly different. Early variety underwent under 28$^{\circ}C$ in maximum while late variety matured under as low as 22$^{\circ}C$. 8. There was a highly significant correlation between the average air temperature (X) during the ripening period, and number of day (Y) for the maturation. And the relationship could be expressed as y=82.30-1.55X. When the average air temperature during the period was within the range of 18$^{\circ}C$ to 28$^{\circ}C$, the ripening period was shortened by 1.55 days with increase of 1$^{\circ}C$. Considering varieties, Kwansan was the highest in shortening the maturing period by 2.24 days and Suwon ＃82 was the lowest showing 0.78 days. It is certain that ripening of rice variety is accelerated at Suwon as the average air temperature increases within the range of 18$^{\circ}C$ to 28$^{\circ}C$. 9. Between number of days to heading (X) related to seeding dates and the accumulated average air temperature (Y) during the ripening period, a positive correlation was obtained. However, there was a little difference in the accumulated average air temperature during the ripening period even seeding dates were shifted to a certain extent. C. Culm- and ear-lengths. 10. In general all the varieties didn't show much variation in their culm-lengths in case of relatively early seeding but they trended to decrease the lengths as seeding was delayed. The magnitude of decreasing varied from young seedlings to old ones. Young seedlings which were seeded during May 21 to June 10 didn't decrease their culm-lengths, while seedlings old as 80 days decreased the length though under ordinary culture. 11. Variation in ear-length of rice varieties show the same trend as the culm-length subjected to the different seeding dates. When rice seedlings aged from 30 to 40 days, the ear-length remained constant but rice plants older than 40 days obviously decreased their ear-lengths. D. Number of panicles per hill. 12. The number of panicles per hill decreased up to a certain dates as seeding was delayed and then again increased the panicles due to the development of numerous tillers at the upper internodes. The seeding date to reach to the least number of panicles of rice variety depended upon the seedling ages. Thirty- to 40-day seedlings which were seeded during May 31 to June 10 developed the lowest number of panicles and 70- to 80-day seedlings sown for the period from April 11 to April 21 reached already to the minimum number of panicles. E. Number of rachillae. 13. To a certain seeding date, the number of rachillae didn't show any variation due to delay of seeding but it decreased remarkably when seeded later than the marginal date. 14. Variation in number of rachillae depended upon seedling ages. For example, 30- to 40-day old seedlings which, were originally seeded after May 31 started to decrease the rachillae. On the other hand, 80-day old seedlings which, were seeded on May 1 showed a tendency to decrease rachillae and the rice plant sown on May 31 could develop narrowly 3 or 4 panicles. F. Defective grain and 1.000-grain weights. 15. Under delay of the seeding dates, weight of the defective grains gradually increased till a certain date and then suddenly increased. These relationships could be expressed with two different linear regressions. 16. If it was assumed that the marginal date for ripening was the cross point of these two lines, the date seemed. closely related with seedling ages. The date was June 10- in 30- to 40-day old seedlings but that of 70- to 80-day old seedlings was May 1. Accordingly, the marginal date for ripening was getting earlier as the seedling stage was prolonged. 17. The 1.000-grain weight in ordinary culture was the heaviest and it decreased in both early and late cultures. G. Straw and rough rice weights. 18. Regardless of earliness of variety, rice plants under early culture which were seeded before March 22 or April 1 did not show much variation in straw weight due to seedling ages but in ordinary culture it gradually decreased and the degree was became greater in late culture. 19. Relationship between seeding dates (X) and grain weight related to varieties and seedling ages, could be expressed as a parabola analogous to a line (Y=77.28-7.44X$_1$-1.00lX$_2$). That is, grain yield didn't vary in early culture but it started to decrease when seeded later than a certain date, as seeding was delayed. The variation was much greater in cases of late planting and prolongation of seedling age. 20. Generally speaking, the relationship between grain yield (Y) and number of days to heading (X) was described with linear regression. However, the early varieties were the highest yielders within the range of 60 to 110, days to heading but the late variety greatly decreased its yield since it grows normally only under late culture. The grain yield, on the whole, didn't increase as number of days to heading exceeded more than 140 days.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.429-444
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• 1988

Considering the recent trent toward the development of multiple-use of forest trees, investigations for comprehensive information on these young stands of Hinoki cypress are necessary for rational forest management. From this point of view, 83 sample trees were selected and cut down from 23-ear old stands of Hinoki cypress at Changsung-gun, Chonnam-do. Various stem growth factors of felled trees were measured and canonical correlaton analysis, principal component analysis and factor analysis were applied to investigate the stem growth characteristics, relationships among stem growth factors, and to get potential information and comprehensive information. The results are as follows ; Canonical correlation coefficient between stem volume and quality growth factor was 0.9877. Coefficient of canonical variates showed that DBH among diameter growth factors and height among height growth factors had important effects on stem volume. From the analysis of relationship between stem-volume and canonical variates, which were linearly combined DBH with height as one set, DBH had greater influence on volume growth than height. The 1st-2nd principal components here adopted to fit the effective value of 85% from the pincipal component analysis for 12 stem growth factors. The result showed that the 1st-2nd principal component had cumulative contribution rate of 88.10%. The 1st and the 2nd principal components were interpreted as "size factor" and "shape factor", respectively. From summed proportion of the efficient principal component fur each variate, information of variates except crown diameter, clear length and form height explained more than 87%. Two common factors were set by the eigen value obtained from SMC (squared multiple correlation) of diagonal elements of canonical matrix. There were 2 latent factors, $f_1$ and $f_2$. The former way interpreted as nature of diameter growth system. In inherent phenomenon of 12 growth factor, communalities except clear length and crown diameter had great explanatory poorer of 78.62-98.30%. Eighty three sample trees could he classified into 5 stem types as follows ; medium type within a radius of ${\pm}1$ standard deviation of factor scores, uniformity type in diameter and height growth in the 1st quadrant, slim type in the 2nd quadrant, dwarfish type in the 3rd quadrant, and fall-holed type in the 4 th quadrant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.409-412
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• 2002

This research was conducted to obtain the fundamental data on salt injury and different responses among cultivars in winter barley (Hordeum vulgare L.). Salts did not affect yield components including number of panicles, stem length, grain number per ear and grain yield while reduced stem dry weight and thousand seed weight significantly with increasing concentrations of salt from 60 to 180 mM. NaCl had less injury effect on barley straw dry weight and thousand seed weight than did $MgSO_4$. Chlorophyll content and relative turgidity in flag leaf were reduced when treated with both salts, while free proline in the salt-treated leaf was increased. Content of proline in salt-treated barley was about 10 folds compared to the control. Based on yield components and physiological traits of flag leaf, the tolerance to salt injury was the greatest in Baegdong, followed by Dongbori#1, Mogpo#55, and Gangbori. The results suggested that salt- stressed barley at reproductive stage had higher free proline content, and that special management in this stage must be considered because salt stress at heading stage affect flag leaf growth as well as yield components Harmfully.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.293-298
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• 2014

This study conducted experiments on the reclaimed land of Saemangeum located in Jeongrabuk-do in order to gain basic information about growth characteristics and yield ability according to soil salinity. Having soil excluding salt as a control group, this study adjusted the specimens' soil salinity to level 4 and then planted four varieties including Ilmichal Corn to investigate the growth or grain yield according to salinity. About the corn establishment rate according to soil salinity, over 97% up to $3.2dS\;m^{-1}$ was established, and then, it was reduced gradually according to the increase of concentration. According to the salt concentration of soil more required growth duration from seeding to heading comparing to non-treatment salt was delayed, at $1.6dS\;m^{-1}$, two days were delayed, at $3.2dS\;m^{-1}$, four to six days were delayed differently by varieties, and at $4.8dS\;m^{-1}$, six to 10 days were delayed. About the plant fresh weight according to soil salinity, Chalok 4 and Eolrukchal indicated 93%~97% or so compared with the salt-free one at $1.6dS\;m^{-1}$, and Chalok No. 4 showed 79% at the salinity of $3.2dS\;m^{-1}$, too, and it was a relatively higher growth percentage than those of the other varieties. In terms of dried seed weight according to soil salinity, compared with the corns cultivated in the control group, averagely 12.1% was lowered at the time of cultivation at $1.6dS\;m^{-1}$, and $3.2dS\;m^{-1}$ 40% was lowered, and about 70% was lowered at $4.8dS\;m^{-1}$. According to the result of examining the point of time that dried seed start to reduce due to soil salinity with the regression equation, soil salinity which starts the reduction of grain weight is $1.67dS\;m^{-1}{\sim}2.18dS\;m^{-1}$, and it differs by varieties, and EC of 50% that the yield reduces in half is $2.96dS\;m^{-1}{\sim}4.45dS\;m^{-1}$. And the degree of influence on each of the growth factors according to soil salinity is founded to be in the order of establishment rate

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.249-255
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• 1987

To find out the optimum planting date of silage corn in the rice black-streaked dwarf virus (RBSDV) pre-valent area, a resistant hybrid of Jinjuok and a susceptible hybrid of Suweon 19 were planted at the 8 planting dates from April 1 to June 10 at the la-day intervals. Considering escape of RBSDV and silage yield, the optimum planting date seems to be during the April in both hybrids. At the April plantings silage yield of two hybrids ranged from 17 to 23 tons/ha on the dry matter base due to a lower infection rate and higher tolerance to RBSDV and there was no difference in silage yield between two hybrids. At the May plantings yield of ear, stover, and silage, culm length, and digestible dry matter decreased significantly as planting date delayed due to an increase in RBSDV infection rate in both hybrids although performance of a resistant hybrid of Jinjuok was better than a susceptible hybrid of Suweon 19. At the June 10 planting RBSDV infection rate was low and performance of corn was better than that at the May plantings but poorer than that at the April plantings. The peak of small brown planthopper population occurred in late March or early April, middle June, middle July, and early September although it fluctuated a little yearly. Very low small brown planthopper population during the May may attribute to a lower RBSDV infection and high silage yields at the April plantings because the plants grow enough to be tolerant when infected by RBSDV in middle June. However, at the May plantings plants are too young to be tolerant when infected by RBSDV in middle June.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.65-69
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• 2007

The effects of bamboo (Phyllostachys nigra var. henenis Strapf) leaf extract (BLE) on the changes of ultraviolet (UV) light B radiation-induced apoptotic sunburn cell (SBC) and epidermal ATPase-positive dendritic cell (DC) in SKH1-hr or ICR mouse were investigated. The mice were treated with UVB ($200mJ/cm^2$) and were sacrificed 24 hours later. BLE (50 mg/kg of body weight) or vehicle (saline) was given i.p. at 36 and 12 hours before irradiation, and 30 minutes after irradiation. BLE cream (0.2%) or cream base (vehicle) was also topically treated at 24 hours and 15 minutes before irradiation, and immediately after irradiation. The skin of SKH1-hr mouse prepared from the back of untreated mice exhibited about 0.3 SBC/cm length of epidermis, and 24 hours after UV irradiation, the applied areas show an increased number of SBCs. But the frequency of UVB-induced SBC formation was significantly reduced by intraperitoneal injection (59.0%) and topical application (31.8%) of BLE extract. The numbers of DC in normal ICR mouse were $628.00{\pm}51.56\;or\;663.20{\pm}62.58\;per\;mm^2$ of ear epidermis. By 1 day after UVB treatment, the number of ATPase-positive $cells/mm^2$ were decreased by 39.0% or 27.1% in i.p. or topical application group with vehicle. The frequency of UVB ($200mJ/cm^2$)-induced DC decrease was reduced by treatment of BLE as 25.7% in i.p. group and 3.2% in topical application group compared with the irradiation control group. The results presented herein that BLE administration could reduce the extent of skin damages produced by UVB.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.4
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• pp.216-224
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• 2023

Since maize (Zea mays L.) originated in central and south America, it requires warm climate conditions throughout its growing season. Growth halts when night-time temperatures drop below 10℃, and the plant may die if temperature reach -1.7℃. Thus, temperature should be maintained between 10 and 30℃ from seeding to maturity. The germination temperature for maize should be at least 8-11℃, whit an optimal range 32-34℃. Since temperature significantly affects the germination rate and period, it plays a crucial role in maize growth. In this study, we evaluated the quantity and feed value of 11 major varieties to determine those best suited for maize cultivation as feed in higher latitude, specifically in Democratic People's of Republic of Korea, below 38 degrees north. A cultivation test was also conducted in Suwon in Republic of Korea, to assess adaptability in areas south of Mt. Suyang. Among the varieties tested, Shinhwangok2 reached silking the fastest, in 65 days, while Gwangpyeongok took the longest at 75 days. The stem length of all varieties exceeded 230 cm. Gwangpyeongok had the tallest stems, while Daanok and Shinhwangok2ho displayed the highest ear ratios. Dacheongok presented the highest values in both dry matter and TDN quantity, with 31,420 kg/ha and 21,66 kg/ha respectively. Pyeonggangok had the highest crude protein content at 8.0%. TDN (%) ranged from 57-68%, with Hwangdaok reaching up to 68%. Based on these findings, Dacheongok and Pyeonggangok appear to be the most suitable varieties for cultivation in terms of both quantity and feed value.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.10
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• pp.1-43
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• 1971

Experiment I: The objective of this study was to know variation in some selected agronomic characters of sweet sorghum when planted in several growing seasons. The 17 different sweet sorghum varieties having various maturities, and plant, syrup and sugar types were used in this study which had been carried out for the period of two years from 1968 to 1969 at Industrial Crops Division of Crop Experiment Station in Suwon. These varieties were planted at an interval of 20 days from April 5 to August 25 both in 1968 and 1969. The experimental results could be summarized as follows: 1. As planting was made early, the number of days from sowing to germination was getting prolonged while germination took place early when planted at the later date of which air temperature was relatively higher. However, such a tendency was not observed beyond the planting on August 25. In general, a significant negative correlation was found between the number of days from sowing to germination and the average daily temperature but a positive correlation was found between the former and the total accumulated average temperature during the growth period. 2. The period from sowing to heading was generally shortened as planting was getting delayed. The average varietal difference in number of days from sowing to heading was as much as 30.2 days. All the varieties were grouped into early-, medium and late-maturing groups based upon a difference of 10 days in heading. The average number of days from sowing to heading was 78.5$\pm$4.5 days in the early-maturing varieties, 88.5$\pm$4.5 days in the medium varieties and 98.5$\pm$4.5 days in the late-maturing varieties, respectively. The early-maturing varieties had the shortest period to heading when planted from July 15 to August 5, the medium varieties did when planted before July 15 and the late-maturing varieties did when planted before June 5. 3. The relationship between the sowing date (x) and number of days from sowing to heading could be expressed in an equation of y=a+bx. A highly positive correlation was found between the coefficient of the equation(shortening rate in heading time) and the average number of days from sowing to heading. 4. The number of days from sowing to heading was shortened as the daily average temperature during the growth period was getting higher. Early-maturing varieties had the shortest period to heading at a temperature of 24.2$^{\circ}C$, medium varieties at 23.8$^{\circ}C$ and late-maturing varieties at 22.9$^{\circ}C$, respectively. In other words, the number of days from sowing to heading was shortened rapidly in case that the average temperature for 30 days before heading was 22$^{\circ}C$ to $25^{\circ}C$. It prolonged relatively when the temperature was lower than 21$^{\circ}C$. 5. There was a little difference in plant height among varieties. In case of early planting, no noticeable difference in the height was observed. The plant height shortened generally as planting season was delayed. Elongation of plant height was remarkably accelerated as planting was delayed. This tendency was more pronounced in case of early-maturing varieties rather than late-maturing varieties. As a result, the difference in plant height between the maximum and the minimum was greater in late-maturing varieties than in early-maturing varieties. 6. Diameter of the stalk was getting thicker as planted earlier in late-maturing varieties. On the other hand, medium or early-maturing varieties had he thickest diameter when they were planted on April 25. 7. In general, a higher stalk yield was obtained when planted from April 25 to May 15. However, the planting time for the maximum stalk yield varied from one variety to another depending upon maturity of variety. Ear]y-maturing varieties produced the maximum yield when planted about April 25, medium varieties from April 25 to May 15 and late-maturing varieties did when planted from April 5 to May 15 respectively. The yield decreased linearly when they were planted later than the above dates. 8. A varietal difference in Brix % was also observed. The Brix % decreased linearly when the varieties were planted later than May 15. Therefore, a highly negative relationship between planting date(x) and Brix %(y) was detected. 9. The Brix % during 40 to 45 days after leading was the highest at the 1st to the 3rd internodes from the top while it decreased gradually from the 4th internode. It increased again somewhat at the 2nd internode from the ground level. However, it showed a reverse relationship between the Brix % and position of internode before heading. 10. Sugar content in stalk decreased gradually as planting was getting delayed though one variety differed from another. It seemed that sweet sorghum which planted later than June had no value as a sugar crop at all. 11. The Brix % and sugar content in stalk increased from heading and reached the maximum 40 to 45 days after heading. The percentage of purity showed the same tendency as the mentioned characters. Accordingly, a highly positive correlation was observed between. percentage of purity and Brix % or sugar content in stalk. 12. The highest refinable sugar yield was obtained from the planting on April 25 in late-maturing varieties and from that on May 15 in early-maturing varieties. The yield rapidly decreased when planted later than those dates. Such a negative correlation between planting date(x) and refinable sugar yield(y) was highly significant at 1% level. 13. Negative correlations or linear regressions between delayed planting and the number of days from sowing to germination. accumulated temperature during germination period, number of days to heading, accumulated temperature to heading, plant height, stem diameter, stalk weight, Brix %. sugar content, refinable sugar yield or Purity % were obtained. On the other hand, highly positive correlations between the number of days from sowing to heading(x) and Brix %, sugar content, purity %, refinable sugar yield, plant height or stalk yield, between Brix %(x) and purity %, refinable sugar yield or stalk yield, between sugar content(x) and purity% or refinable sugar yield(y), between purity %(x) and refinable sugar yield and between daylength at heading(x) and Brix %. number of days from sowing to heading, sugar content, purity % or refinable sugar yield (y), were found, respectively. Experiment II: The 11 varieties were selected out of the varieties used in Experiment I from ecological and genetic viewpoints. Complete diallel cross were made among them and the heading date, stalk length, stalk yield, Brix %, syrup yield, combining ability and genetic behavior of F$_1$ plants and their parental varieties were investigated. The results could be summarized as follows: 1. In general, number of days to heading showed a partial dominance over earliness or late maturity or had a mid-value, though there were some specific combinations showing a complete dominance or transgressive segregation in maturity. Some combinations showed relatively high general or specific combining abilities in maturity. Therefore, a 50 to 50 segregation ratio in heading date could be estimated in this study and it might be positive to have a selection in early generation since heritability of the character was relatively high. 2. A vigorous hybrid vigor was observed in stalk length. A complete or partial dominant effect of long stalk was obtained. The general combining ability and specific combining ability of stalk length were generally high. Long and short stalks segregated in a ratio of 50:50 and its heritability was relatively low. 3. Except for several specific combinations, high stalk yield seemed to be partial dominant over the low yield. Some varieties demonstrated relatively high general as well as specific combining abilities. It was assumed that several recessive genes were involved in expression of this character. The interaction among regulating recessive genes was also obtained. Accordingly, the heritability of stalk yield seemed to be rather low. 4. The Brix % of hybrid plants located around mid-parental value though some of them showed much higher or lower percentage. It could be explained by the fact that such behavior might be due to partial dominance of Brix %. The varieties with, relatively higher Brix % were high both in general. and specific combining abilities. Therefore, it could be recommended to use the varieties having higher sugar content in order to develop higher-sugar varieties. 5. The syrup yield seemed to be transgressively segregated or completely dominant over low yield. Hybrid vigor of syrup yield was relatively high. No-consistent relationship between general combining ability and specific combining ability was observed. However, some cases demonstrated that the varieties with relatively higher general combining ability had relatively lower specific combining ability. It was assumed that the frequencies of dominant and recessive alleles were almost same.