• Korean Journal of Weed Science
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• v.5 no.1
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• pp.50-55
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• 1985

Effects of weed removal time on maize growth and yield were evaluated in the fields dominated with Poligonum spp., Chenopodium album, Echinochloa crusgalli and Digitaria adsendens from 1982 to 1983 in Suweon. Weed removal treatments were as follows: (a) kept weedfree all season, (b) weeded at 10 day intervals after maize emergence but stopped weeding at 3,5,7,9 leaf stages, (c) weeds initially removed at 3,5,7 and 9 leaf stages and the plots then kept weed free, (d) weeds left all season. Maize kept weed free from maize emergence to 7 leaf stages showed no grain yield reduction due to competition from weeds emerging later, but weeding from emergence to 3 and 5 leaf stages reduced grain yield 46 and 44%, respectively, in 1982 and 29 and 18%, respectively, in 1983. Weeding at 3 leaf stage and thereafter did not influence grain yield but initial weedings at 5, 7 and 9 leaf stages reduced grain yield 10, 36, and 67%, respectively, in 1982 and 14,18, and 21%, respectively, in 1983. Responses of maize to weeding time in the dry matter yields were same as in the grain yields.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.401-411
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• 2015

Drought stress has detrimental effects on the seedling development, vegetative/ reproductive growth, photosynthesis, root proliferation, anthesis, anthesis-silking interval (ASI), pollination and grain yield in maize. Typically, two weeks before silking through pollination are an important time in maize life. Here we reviewed the effects of drought stress on growth, physiological/ molecular researches for drought tolerance, and breeding to genomics in maize. Drought stress during kernel development increases leaf dying and lodging, decreases grain filling period and grain yield. Physiological factors of drought stress/ effects are water content, water deficits, and water potential. Nowdays molecular marker assisted breeding method is becoming increasingly useful in the improvement of new germplasm with drought stress tolerance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.1
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• pp.18-28
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• 2021

The growth period and productivity of cropping system of winter wheat-rice, winter wheat-bean and winter wheat-grain corn for 4 years from 2015 to 2018 were compared at the experimental field of National Institute of Crop Science in Miryang city. The harvest period of winter wheat was in mid-June, and summer crops were sown (transplanted) in late June. In transplanting of rice in late June, there was no difficulty in securing the heading of panicle and the yield of rice, but there was a lot of trouble in sowing wheat in proper time because the harvest time of rice was delayed to early November due to late maturity of rice, particularly in the mid-late maturing cultivar. There was no problem in soybean planting after winter wheat because the proper period of soybean planting is late-June. In addition, there was no problem in winter wheat sowng after soybean because the maturity period of soybean was mid-October. Selection of grain maize in double cropping with winter wheat in terms of growing periods, was desirable because grain maize had the fastest maturity among summer crops. In double cropping of winter wheat-summer crops, wheats combined with soybean and grain maize showed stable yields during three years, but there was a risk of yield declines in the wheat combined with rice in heavy rainfall year. It was possible to secure high yields in three summer crops as yields of rice, soybean, and corn were 600, 350, and 800 kg/10a, respectively. Summer crops with medium maturity was recommended because of no significant difference in yield between medium maturity and medium-late maturity cultivar. Soil physical properties were improved in soils cultivated with soybean and grain maize. Therefore, It was thought that double cropping systems of winter wheat with soybean and grain maize were superior to that of winter wheat with rice in terms of connecting period between winter wheat - summer crops and improvement of soil physical properties, and total income, particularly in soybean.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2014.10a
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• pp.1-24
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• 2014

This study uses geo-spatial crop modeling to quantify the biophysical impact of weather extremes. More specifically, the study analyzes the weather extreme which affected maize production in the USA in 2012; it also estimates the effect of a similar weather extreme in 2050, using future climate scenarios. The secondary impact of the weather extreme on food security in the developing world is also assessed using trend analysis. Many studies have reported on the significant reduction in maize production in the USA due to the extreme weather event (combined heat wave and drought) that occurred in 2012. However, most of these studies focused on yield and did not assess the potential effect of weather extremes on food prices and security. The overall goal of this study was to use geo-spatial crop modeling and trend analysis to quantify the impact of weather extremes on both yield and, followed food security in the developing world. We used historical weather data for severe extreme events that have occurred in the USA. The data were obtained from the National Climatic Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA). In addition we used five climate scenarios: the baseline climate which is typical of the late 20th century (2000s) and four future climate scenarios which involve a combination of two emission scenarios (A1B and B1) and two global circulation models (CSIRO-Mk3.0 and MIROC 3.2). DSSAT 4.5 was combined with GRASS GIS for geo-spatial crop modeling. Simulated maize grain yield across all affected regions in the USA indicates that average grain yield across the USA Corn Belt would decrease by 29% when the weather extremes occur using the baseline climate. If the weather extreme were to occur under the A1B emission scenario in the 2050s, average grain yields would decrease by 38% and 57%, under the CSIRO-Mk3.0 and MIROC 3.2 global climate models, respectively. The weather extremes that occurred in the USA in 2012 resulted in a sharp increase in the world maize price. In addition, it likely played a role in the reduction in world maize consumption and trade in 2012/13, compared to 2011/12. The most vulnerable countries to the weather extremes are poor countries with high maize import dependency ratios including those countries in the Caribbean, northern Africa and western Asia. Other vulnerable countries include low-income countries with low import dependency ratios but which cannot afford highly-priced maize. The study also highlighted the pathways through which a weather extreme would affect food security, were it to occur in 2050 under climate change. Some of the policies which could help vulnerable countries counter the negative effects of weather extremes consist of social protection and safety net programs. Medium- to long-term adaptation strategies include increasing world food reserves to a level where they can be used to cover the production losses brought by weather extremes.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.4
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• pp.565-569
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• 2002

Thirty six young New Zealand white rabbits were used in a randomised complete block (RCB) design with a $3{\times}2$ factorial treatment experiment to study the suitability of sorghum as substitute for maize in the diet of growing rabbits in Kenya. Six different diets were formulated to contain 35% of one of the three different types of grain (maize, white sorghum or brown sorghum) and one of the two different levels of crude protein (CP) 16 or 18.5% and fed to growing rabbits for a period of six weeks. The tannin content of the grains was 0.05, 0.52 and 5.6% chatechin equivalents for maize, white and brown sorghum respectively. Weaning weight at 35 days of age was used as the blocking criterion at the beginning of the experiment. Results of feed intake, weight gain, feed conversion efficiency, feed digestibility, as well as the blood parameters, indicated that white sorghum was not significantly different from maize. Animals fed on diets containing brown sorghum had a lower average daily gain (ADG) and a poorer feed conversion efficiency (FCE) (p<0.01) in comparison with those fed on diets containing maize or white sorghum. The 18.5% CP level gave a better FCE (p<0.05) compared with the 16% CP level. However, increasing the level of CP did not improve the utilisation of any of the grains. It was concluded that white sorghum could effectively substitute maize in the diet of growing rabbits. On the other hand, the use of brown sorghum in the diets of growing rabbits may compromise their growth rate. This may be due to the high concentration of tannins in the brown sorghum.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.384-388
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• 2003

Twenty yearling lambs of Southeast Nigeria dwarf, liveweight ($18{\pm}1.9 kg$) were grouped into 5 treatments. Dry brewer's grain was substituted for maize offal in the experiment diets namely A to E at 0%, 15%, 30%, 45% and 60% respectively, as supplement to low quality, dry season cassava leaf top and Andropogan gayanus hay at 1:1 ratio that lasted for 56 days. After which 5 of the lambs (average bodyweight=$24.3{\pm}1.5kg$) were transferred to metabolism crates to determine the digestibility and nitrogen/protein balance studies. While the mean group intakes were (945.9, 996.1, 1,040.5, 1,148.5 and 1,037.7 g conc. DM/day), the growth rates were (115.1, 124.1, 152.5, 168.5 and 123.1 g liveweight gain/day), respectively. There was a recorded decline in both intake (p>0.05) and growth rate (p<0.05) as the level of dry brewer's grain was increased beyond 45% of the supplement. Similar trend was observed on the protein and organic matter efficiency ratios (p>0.05) together with the organic matter intake. The urine nitrogen output was also significant (p>0.05). The work further revealed that, at a certain critical level of intake, dry brewer's grain is able to support growth rates measurable to or better than those noted when feeding maize offal to lambs, and went on to prove dry brewer's grain as an attractive supplementary feed for the drier months of the year, in the Southeast of Nigeria.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47
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• pp.107-123
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• 2002

This paper is intented to present a information of various aspects of quality related characteristics and standards for grades in maize. Maize is world's one of the three most popular cereal crops and a primary energy supplement and can contribute up to 30, 60, and 98% of the dairy diet's protein, net energy, and starch, respectively. Maize is also processed into industrial goods by wet or dry milling. Sweet corn is a leader among vegetable crops and its production for fresh or processing markets is a major industry in many countries. Over the years, the combined efforts of breeders and geneticists, biochemists, food scientists, and others have helped bring us to the point where we understand issues related to sweet corn quality. Traditional criteria for selecting corn hybrids have been based primarily on agronomic factors, including grain production, disease resistance, drought tolerance, and storage characteristics. Little emphasis has been placed on the quality and nutritional values of corn. Although there is widespread interest for value-enhanced corns have increased tremendously in the last five years, there is limited information available on the production and comparing the quality attributes of specialty grains with those of normal yellow dent corn. Most countries have developed national maize standards, aiming to provide a framework for trade, both internal and external. Where trading involves direct choice and price negotiation in front of the commodity, grading standards are rarely employed; quality is assessed visually and is influenced by end-use, and the price is determined more by local rather than national factors. The use of an agreed standard will provide an unambiguous description of the quality of the consignment and assist in the formation of a legally-binding contract. Standards can also be seen to protect consumers rights through setting limits to the amount of unsuitable or noxious material.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.222-230
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• 2020

Maize grain quality can be improved by raising lysine content, which is an essential amino acid present in insufficient quantities in normal maize. Maize varieties with such modifications are known as quality protein maize (QPM). To date, no Korean maize cultivars contain high amounts of lysine. To introduce quality protein maize to Korean cultivars, we crossed QPM CIMMYT maize lines (CML) with KS140, an elite inbred line used as a parent of several cultivars such as 'Gangdaok' and 'Pyeonganok'. We analyzed the phenotypic characteristics of F₁ plants as well as the protein contents, amino acids, and fatty acids profiles of the self-pollinated seeds of the F₁ hybrids, and evaluated the feasibility of CML as a source of QPM. Days to anthesis of the CML ranged from 78 to 90 days after planting (DAP), whereas a range of 81~87 was recorded for F₁ hybrids. The average days to anthesis was 85 for KS140, CML, and the F₁ hybrids. The protein content of the CML was measured to be between 9.1 and 12.1%, with the highest and lowest values being recorded in CML153 and 191, respectively. The F₁ hybrids had protein contents of 9.1~11.1%, and the highest content was observed in KS141/CML188. The fatty acids profiles were very similar across all analyzed maize samples, and linoleic acid (C18:2) composed the greatest proportion. Glutamic acid made up the largest proportion of amino acids in all maize samples. Lysine composition was highest in CML155 (6.92% of all amino acids), with an average composition of 4.83% across the CML. In contrast, KS140 showed a lysine content of 2.51%. In F₁ hybrids, the average lysine composition was 3.46%, and KS140/CML164 (4.18%) and KS140/CML163 (4.99%) contained more lysine than either parent. Taken together, these results indicate that CML could become promising QPM sources to improve grain quality in Korean maize cultivars.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.9
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• pp.1238-1244
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• 2001

Two calorimetric experiments were performed to investigate the effects of two diets with same concentrate: roughage ratio (70:30) but varying in composition on energy metabolism and methane production in faunated (F) and defaunated (DF) Muzaffarnagari sheep. For experiment I, ten animals were divided equally into two groups of which one was kept normally F as such while other was DF using 10% sodium lauryl sulphate. All the animals were offered diet I which comprised of oat hay and concentrate mixture I (CM I) containing maize grain (93%) as a major ingredient in 70:30 ratio. Similarly, the experiment II was conducted for which four F and four DF sheep (same as used for experiment I) were switched to diet II that consisted of maize hay and CM II (maize grain 59% + molasses 36%). Through diet II, DM intake in DF sheep was significantly (p<0.05) lower. Intake of GE through both the diets was similar in F and DF sheep. Digestibility of DM, OM, CP and GE and also metabolisability (ME/GE) was similar in F and DF sheep on both the diets. Total urinary energy loss did not differ in F and DF on both the diets, but methane energy loss as a percent of GE in DF was significantly (p<0.05) lower on diet I (3.75 vs 2.48), while it did not differ on diet II (3.20 vs 3.60). Heat production was significantly (p<0.01) reduced in DF on both the diets. Although, efficiency of utilisation of ME for maintenance calculated as per ARC (1984) did not differ in F and DF on both the diets, efficiency for maintenance and growth was higher (0.60 vs 0.672) on diet I in DF. It was inferred that methane production in DF sheep reduces on good quality hay-based diet supplemented with slowly fermentable carbohydrate (maize grain) but supplementation of molasses (rapidly fermentable CHO) nullify this effect when sheep were fed diets with concentrate: roughage ratio of 70:30.

• Korean Journal of Breeding Science
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• v.51 no.2
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• pp.105-109
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• 2019

'Hwangdaok', a new maize F1 hybrid (Zea mays L.), was developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2016. The high-yielding yellow dent hybrid named 'Hwangdaok' was obtained by crossing between two inbred lines, 'KS203' and 'KS190'. After advanced yield trial in Suwon in 2012, regional yield trial was subsequently carried out to evaluate the growth and yield of 'Hwangdaok' at three different locations from 2014 to 2016. The number of days to silking of 'Hwangdaok' is 76. The plant height is 262 cm and ear height ratio is 51%, which are similar to those of 'Jangdaok'. It has resistance to lodging. The number of ears per 100 plants is 95. The ear length is 21.3 cm and weight of 100 seeds is 34.7 g, similar to those of 'Jangdaok'. It has moderate resistance to southern leaf blight (Bipolaris maydis) and European corn borer (Ostrinia nubilalis). The grain yield (10 ton/ha) of 'Hwangdaok' is 6% higher than that of 'Jangdaok'. The seed production rate of 'Hwangdaok' is acceptable due to good synchronization of flowering period during crossing between the seed parent, KS203, and the pollen parent, KS190, in Yeongwol. F1 seed yield was 1.68 ton/ha. 'Hwangdaok' can be a suitable cultivar to plain areas in Korea. (Variety registration No. 7502).