Beom-Young Son

Comparison of Growth Characteristics and Yield of Silage Corn Hybrids by Different Planting Dates at Paddy and Upland Field

ABSTRACTThis study was conducted to evaluate growth characteristics and yield of silage corn hybrids by different planting dates at paddy and upland field. Days to silking by different planting dates at paddy field were 81 days at planting on April 22, 70 days on May 20 and 62 days on June 10, respectively, and they were getting shorter as planting date delayed. There was no significant difference in days to silking between paddy and upland field. Plant height in paddy field was no significant difference between at planting on April 22 and on May 20, and it was shortened sharply at planting on June 10. There was no significant difference in plant height between paddy and upland field. There was no significant difference in lodging by different planting dates in paddy field. There was significant difference in lodging between paddy and upland field(P<0.05). There was no significant difference in stay-green by different planting dates in paddy field, and no significant difference between paddy and upland field. Ear ratios to total dry matter in paddy field were 43% at planting on April 22, 41% on May 20 and 28% on June 10, respectively, and it was lower as planting date delayed. There was no significant difference in ear ratios to total dry matter between paddy and upland field. Fresh yields in paddy field were lower with 14% at planting on May 20 and 32% on June 10 compared to on April 22 as planting date delayed. There was no significant difference in fresh yield between paddy and upland field. Dry matteryields in paddy field were higher with 9% at planting on May 20 and lower with 24% on June 10 compared to at planting on April 22 as planting date delayed. Dry matter yield in paddy field was lower with 9% compared to 1,931kg/10a at planting on April 22. TDN(Total digestible nutrients) yields in paddy field were higher with 5% at planting on May 20 and lower with 28% on June 10 compared to at planting on April 22 as planting date delayed. TDN yield in paddy field was lower with 11% compared to 1,340kg/10a at planting on April 22. (Key words:Paddy field, Silage corn, Planting date, Yield, Dry matter, TDN)

Physiological and Protein Profiling Response to Drought Stress in KS141, a Korean Maize Inbred Line

Understanding the complex response mechanism of a crop to drought is the major step in the developing of tolerant genotypes. In our study, to investigate physiological traits and proteome dynamics, an inbred maize (Zea mays L.) line (KS141) was subjected to 10 days of water-withholding at the V5 or V6 leaf stage. The subsequent analysis of their physiological parameters revealed a decreased relative leaf water content, Fv/Fm, stomatal conductance, net CO2 assimilation rate, leaf transpiration, and water use efficiency, resulting in severe growth retardation of leaf area, stem length and width, aerial part, and root dry matter at 3 and 10 days after withholding water. However, aerial part and root dry matter were little changed during drought stress for 3 days. To understand the proteome dynamics during the 10-day drought stress in maize leaves, comparative proteome analysis was carried out between the well-watered and drought-treated leaves. Proteins were extracted using phenol extraction method from leaves with/without drought stress, and then separated by 2-DE. After 2-DE gel analyses, 14 differentially expressed protein spots were identified by MALDITOF mass spectrometry. Out of 14, eleven and three protein spots were found to be up- or down-regulated, respectively. Interestingly, stress-related proteins such as glutathione S-transferase, abscisic stress-ripening proteins, and pathogenesis-related proteins were increased by drought stress. Our study may provide molecular mechanisms and selective markers for drought tolerant maize genotypes.

Change of Seed Yield, Germination Rate and Hard Seed Rate with Harvest Time in Hairy Vetch (Vicia villosa Roth)

This experiment was conducted to investigate an optimum harvest time for hairy vetch (HV) seed production. The seeds were harvested at 5 times, 35, 42, 48, 54, and 58 days after flowering (DAF) in 2009 and 2010. In 2011, 3 times of harvest, 39, 49, and 53 DAF were done at Suwon, middle part of Korea. HV plants were harvested and threshed by manually at each time. Seed yield, yield components, germination rate, hard seed rate, and viviparous germination rate were investigated. The highest seed yield represented 54 DAF in 2009, 42 DAF in 2010, and 49 DAF in 2011. When the triticale, HV support plant, comes to early lodging, the time of highest yield was delayed. 1,000-seed weight linearly increased from 35 DAF to 54 DAF. The later harvested seed showed a trend of increasing germination and hard seed ratio. However, viviparous germination had occurred because of in rainy season. In conclusion, it was presumed that an optimum harvest time for safe seed production in HV should be during 42 DAF ~ 54 DAF before the rainy season considering seed yield, 1,000-seed weight and germination.

Impact of the consecutive days of visible wilting on growth and yield during tassel initiation in maize ( Zea Mays L.)

Maize (Zea mays L.) is a major crop with different uses but shows significant susceptibility to drought stress. Recent climate change has caused prolonged drought stress, but in most countries maize production relies on rain-fed cultivation. This study was to investigate the impact of the consecutive days of visible wilting (DAW) during tassel initiation (V6) using two types of Korean maize hybrids, Gwangpyeongok (GWP) and Ilmichal (Ilmi). The traits related to plant growth and yield were measured at harvest. Drought stress during tassel initiation linearly reduced plant elongation and dry matter accumulation with the length of DAW increasing but did not affect the leaf number per plant. Our results from the simple linear regression analysis indicated that silking of GWP and Ilmi would be delayed by 0.78 and 0.61 days per DAW, respectively, which was similar to anthesis. Still, little change was observed for interval between anthesis and silking under the same condition. The kernels per row were very dependent on the length of DAW but the rows per ear were not. The percentage of filled grains and the 100- grain weight were significantly reduced only at 15- or 20-DAW and more markedly so in Gwangpyeongok at 20-DAW. The filled grain number per plant showed a gradual logistical decline mainly due to decreases in the kernels per row. All these reductions may be because initiation and growth of tassel, ear, and kernels and internode elongation beginning around V6 are sensitive to water deficits. Probit analysis revealed that the DAW to cause 50% reduction in plant grain yield was about 12 and 20 days in GWP and Ilmi, resulting in about 4.5 and 2.7% reduction a day of DAW, respectively. These results indicate that Gwangpyeongok may be more sensitive to drought stress during tassel initiation than Ilmichal.

Response of Growth Characteristics and Yield of Silage Corns at Different Regions

This study was carried out to compare growth characteristics and yield of silage corn hybrids at four different regions (Hwaseong, Dangjin, Gochang and Pyeongchang). Two domestic corn hybrids, `Kwangpyeongok` and `Gangdaok`, and two imported corn hybrids, `P3394` and `32P75` were used in this study. Plant height and ear height ratio were not significantly different among corn hybrids. `Kwangpyeongok` was the strongest of all corn hybrids for lodging. The others except `Kwangpyeongok` were similar to lodging. All corn hybrids were excellent to stay-green. Incidence of southern corn leaf blight (Bipolaris maydis) was low at all corn hybrids. `32P75` was 10.1%, the most of all corn hybrids for incidence of BSDV (black streaked dwarf virus). `Kwangpyeongok` and `Gangdaok` were stronger than `32P75` for BSDV. Fresh yield of `Kwangpyeongok` and `Gangdaok` were the most of all corn hybrids as 74.85 and 76.68 ton/ha and `P3394` was the least of all corn hybrids as 64.97 ton/ha. Dry matter yield as 18.83~21.92ton/ha and TDN yield as 12.73~14.52 ton/ha were not significantly different among corn hybrids.

Single Cross Maize Hybrid for Silage with Lodging Tolerance and High Yield, 'Dacheongok'

Dacheongok’, a new maize F1 hybrid (Zea mays L.), is developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2016. The high-yielding hybrid, named ‘Dacheongok’ was bred by crossing between two inbred lines, ‘KS197’ and ‘KS202’. It is a yellow dent maize hybrid. After advanced yield trial of ‘Dacheongok’ in Suwon for one year, regional yield trial was subsequently carried out for evaluation of its growth and yield at four different locations from 2014 to 2016. The days to silking of ‘Dacheongok’ are 80, similar to ‘Kwangpyeongok’. The plant height of ‘Dacheongok’ is 267 cm, similar to ‘Kwangpyeongok’, and its ear height ratio is 51%, similar with that of ‘Kwangpyeongok’. It has resistance to lodging. The stay-green of ‘Dacheongok’ is not different with that of ‘Kwangpyeongok’. The number of ear per 100 plants of ‘Dacheongok’ is 95, similar to ‘Kwangpyeongok’. The ear length of ‘Dacheongok’ is 18.6 cm, longer than that of ‘Kwangpyeongok’. The weight of 100 seeds of ‘Dacheongok’ is 29.8 g, similar to that of ‘Kwangpyeongok’. It has moderate resistance to southern leaf blight (Bipolaris maydis). It has moderate resistance to European Corn Borer (Ostrinia nubilalis). The dry matter yield (23.69 ton/ha) of ‘Dacheongok’ was 10% higher than that of ‘Kwangpyeongok’. The TDN (Total Digestible Nutrients) yield (16.11 ton/ha) of ‘Dacheongok’ was 7% higher than that of ‘Kwangpyeongok’. The seed production of ‘Dacheongok’ was acceptable due to a good synchronization of flowering period during crossing between the seed parent, KS197, and the pollen parent, KS202, in Yeongwol and F1 seed yield was 2.46 ton/ha. ‘Dacheongok’ would be a suitable cultivar to all plain area in Korea. (Variety registration No. 7054)

Changes in the Functional Components and Radical Scavenging Activity of Korean Maize Hybrids According to Different Cropping Seasons

We evaluated the proximate composition, free sugar content, fatty acid composition, carotenoid content, total phenol content, and radical scavenging activity of the grain from various Korean maize hybrid cultivars grown in two different cropping seasons. The moisture, crude ash, crude fat, crude protein, total starch, and amylose contents were significantly higher in most of the maize hybrid cultivars when grown in the early-season than when grown in the late-season. The free sugar content, fatty acid composition, carotenoid content, and total phenol content differed significantly between cultivars and cropping seasons. The highest unsaturated fatty acid compositions of maize hybrids of early-season and late-season were 86.05 and 86.29%, respectively, in the Daanok cultivar. The carotenoid contents were significantly higher in maize hybrids of late-season compared to those of early-season. The highest total phenol content was 108.09 mg/100 g in Singwangok of the late-season. The radical scavenging activity of maize hybrids differed significantly between cultivars and cropping seasons.

Evaluation of waterlogging tolerance with the degree of foliar senescence at early vegetative stage of maize ( Zea mays L.)

Maize is highly susceptible to waterlogging, which is becoming one of worldwide abiotic threats in many agricultural areas. This study was evaluated to establish the screening method and to find tolerant maize genotypes. Six Korean maize inbred lines were subjected to waterlogging at V3 for 15 days using a big size pot with single maize plant (big pot method) and a box containing 31 maize plants at a time (box method). The degree of foliar senescence and the number of senescent leaves were better indicators for selecting waterlogging tolerant maize genotypes than SPAD value and plant height. The degree of foliar senescence revealed that KS124, KS140, and KS141 are tolerant, and KS85 is susceptible to waterlogging at the early growth stage. These responses of foliar senescence were in clear accordance with those of plant grain yield, which was supported by stress tolerance index for grain yield. The box method also showed the similar response of foliar senescence to the big pot method. Therefore, this box method based on foliar senescence may be simple and efficient for large-scale screening of maize germplasm against waterlogging stress. It was concluded that foliar senescence can be a good indicator for selecting tolerant maize genotypes against waterlogging at the early growth stage.

Effect of plant density on growth and yield of extremely late-planted korean sweet corn hybrids ( Zea mays L.) for fresh market

Sweet corn has a short growing period of 80 to 90 days in Korea, which allows famers to grow this crop using various cropping systems. This objective of this study was to find the optimum plant density for Korean sweet corn (se) hybrids ‘Godangok’ and ‘Guseulok’ when they were grown as the second crop. Plant densities were 5,710, 6,670, and 8,000 plants 10a-1 and planting dates were 20 July and 30 July, 2013. There was no interactive effect between plant density and hybrid for all the analyzed parameters in this study. Increasing plant density up to 8,000 plants 10a-1 led to no significant gain in marketable ear yield. Although the total number of ears was increased about 21 ç 33% at the highest plant density than at lower densities, e.g., 6,670 or 5,710 plants 10a-1, the percentage of marketable ear number and individual ear weight decreased with increasing plant density. Individual ear weight of marketable ears was significantly greater, e.g., by 8 ç 13%, at 5,710 plants 10a-1 and 6,670 plants 10a-1 than at 8,000 plants 10a-1. Similar results were obtained for ear length and width and filled length under the given plant densities, which indicated that increasing plant density may decrease individual ear fresh weight and ear size with good tip fill. Increasing plant density up to 8,000 plants 10a-1 caused the lowest harvest index, which resulted in little gain in fresh ear yield compared to the lower plant densities of 5,710 and 6,670 plants 10a-1. These results indicated that the optimum plant density for those sweet corn hybrids planted in July would be between 5,700 and 6,700 plants 10a-1 in terms of marketable ear yield and quality of marketable ears.