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Let Kn denote the set of all n×n nonnegative matrices with entry sum n. For X∈Kn with row sum vector (r1,…,rn), column sum vector (c1,…,cn), Let ϕ(X)=∏iri+∏jcj−perX. Dittert's conjecture asserts that ϕ(X)≤2−n!/nn for all X∈Kn with equality iff X=[1/n]n×n. This paper investigates some properties of a certain subclass of Kn related to the function ϕ and the Dittert's conjecture.

We denote by Q(A) the set of all matrices with the same sign pattern as A. A matrix A has signed null-space provided there exists a set S of sign patterns such that the set of sign patterns of vectors in the null-space of à is S for each à ∈ Q(A). Some properties of matrices with signed null-spaces are investigated. [ABSTRACT FROM AUTHOR]

Qualitative properties shared by the solutions to the family of linear equations of the form $$Ax=b, \quad (A\in C, b \in B),\eqno(1)$$ where C is a cone in ${\shadR}^{m\times n}$ and B is a cone in ${\shadR}^m$ are studied. In particular, the cones C and B for which the sign patterns of the solutions to (1) are independent of the choice of A ∈ C and b ∈ B are characterized. [ABSTRACT FROM AUTHOR]

A chemical, MNU-induced hulless barley mutant line designated as 'Mutant 98 (M98)' was developed from a Korean hulless waxy barley cultivar, 'Chalssalbori'. The objective of the study was to determine the genetic basis of 'M98' and the possibility of using 'M98' as breeding parent to improve lysine level. Compared to 'Chalssalbori', 'M98' had large embryo and higher lysine content in both the embryo and endosperm. Significantly different lysine content in 'M98' and the other high-lysine barley mutant stocks was observed for two years. However, the genotype by year interaction was not significant. 'M98' was higher than the other high-lysine barley mutant stocks in the percentage of lysine of total amino acid composition (0.75%). The trait of shrunken endosperm of 'M98', which was typical in the high-lysine mutants, was inherited by a single recessive gene. Based on seed morphology and lysine content of F1 seeds, 'M98' had a genetically different gene from the other high-lysine mutants for shrunken endosperm. Segregation of F2 for plump/shrunken endosperm did not fit the expected ratio of Mendelian inheritance except for only one cross combination (GSHO1784 (lys1)/M98). The amino acid analysis of F5 and F6 progenies from the cross between 'M98' and 'Chalssalbori' revealed that the attempt to increase the range of lysine content of plump lines did not go beyond the limit of the average high-lysine barley germplasm. [ABSTRACT FROM AUTHOR]

"Olgreen" (Scale cereal L.), a new rye variety was developed by National Institute of Crop Science(NICS), RDA. It was released in 2008 because of its high biomass yield potential and early maturity. It was developed from an open pollination within 10 rye varieties or lines including "Chochun" in 1995. The line 'SR95POP-S1-1072-1-2-4' was selected for its early maturity and excellent agronomic appearance, and placed in yield trials for two years from 2004 to 2005. It was designated "Homil 38" and placed in regional yield trials at the four locations around Korea from 2006 to 2008, from which the name "Olgreen" was given. Over three years, "Olgreen" averaged 8.88 ton ha-1 of forage yield (based on dry matter) harvested at late April and superior to other varieties with an increase of 10% more than the check variety "Olhomil", and 9% more than the introduced rye "Koolgrazer". Heading date of "Olgreen" was April 20 which was 3 days earlier than that of "Olhomil". It would be recommended as an early rye variety for forage or green manure in South Korea. [ABSTRACT FROM AUTHOR]

"Egreen" rye (Secale cereale L.) was developed by National Institute of Crop Science (NICS), RDA. It was released in 2007 because of its excellent earliness and yield potential. Crossing was made by an open pollination with 10 rye lines in 1995. Many lines from the open pollinated population were handled in a mass selection program in subsequent generations. Among them the line 'SR95POP-S1-116-1-1-2'was selected for earliness and promising agronomic appearance and placed in yield trial for two years from 2003 to 2004. In 2005, it was designated "Homil 34" and subjected to regional yield trials. Over 3 years, "Egreen" averaged 8.34 MT ha-1 of forage yield (based on dry matter) harvested at the heading date of check variety "Olhomil", which was superior to other varieties such as "Olhomil" and "Koolgrazer" with an increase of 8% and 10%, respectively. Heading date of "Egreen" was April 22, 3 days earlier than that of "Olhomil". It would be recommended as a winter crop forforage and green manure before planting either maize or rice in Korea. [ABSTRACT FROM AUTHOR]

"Hyedang", a new covered cultivar derived from the crosses between "Suwon300" and "Haganemugi//CI08397/Haganemugi" developed at the Honam Agricultural Research Institute (HARI), NICS, RDA in 2007. The origin of "Hyedang" is "Iksan 407" (SB951033-B-B-B-72). The initial cross was made in 1995 and the selected line showed a high yield and good quality characteristics under yield trial test in 2004. "Iksan407" consistently performed well for three years (2005-2007) from the four locations of regional yield trial (RYT) in Korea and released as "Hyedang". The characteristics of "Hyedang" were the following: rate III growth habit, green leaf and stem, compact spike and with long rough awns. The heading date was April 25 in upland and April 17 in paddy field, which was 2 and 3 days earlier than that of check cultivar, "Olbori". The culm length was 80 cm which was 8 cm shorter than those of check cultivar. It showed spike length of 4.3 cm and 696 spikes per m2, 51 grains per spike, 35.0 g of 1,000 grain weight and 704 g of test weight. It showed stronger winter hardiness and higher resistance to barley yellow mosaic virus (BaYMV) than those with check cultivar. It showed similar protein content and higher whiteness than those of the check cultivar and diastatic power was higher than that of Olbori. The average yield of the pearled grain in the RYT was 4.17 ton ha-1 in upland and 4.27 ton ha-1 in paddy field, which was 23% and 9% higher than that of the check cultivar, respectively. This cultivar would be suitable for the area above the daily minimum mean temperature of -8E°C in January in Korean peninsula. [ABSTRACT FROM AUTHOR]

A single cross hybrid, Heukjinjuchal, is a black color waxy corn (Zea mays L.) developed by the maize breeding team at NICS in 2008. Heukjinjuchal was produced by crossing two inbred lines, KBW24 as seed parent and KBW2 as pollen parent. Ear length and ear diameter of Heukjinjuchal was 16.0 cm and 4.4 cm, respectively. The ratio of kernel set length/ear length was 89%, similar with that of a check hybrid, Chalok1. It is resistant to Northern corn leaf blight disease and also lodging tolerant. Fresh ear yield of Heukjinjuchal comparable with those of a check hybrid, Chalok1 in regional yield trials for three years. Seed production of this hybrid is relatively easy because of well overlapping period of silking and pollen dispersal between the two parents. This cultivar would be well adaptable to the whole country. [ABSTRACT FROM AUTHOR]