A total of 2,765 accessions were used as the initial set having both seed coat color and 100-seed weight data. As a result of molecular profiling using six SSR markers followed by stratification based on their usages, 335 accessions(12.1%) were selected by clustering based on UPGMA. Since 75 out of 335 accessions were mixed in phenotypic traits as a result of characterization, 260 accessions were finally set as a core set. This core set revealed nearly the same diversity compared with the other results on morphological traits of Korean soybean landraces. In total, 115 alleles(19.2 alleles per locus) were detected in the initial set and 79 alleles(13.2 alleles per locus) were detected in the core set. All 30 major alleles were present in the initial set and in the core set as well. In allele coverage, the core set was 71.4% of the initial set. These comparisons of number of alleles, gene diversity and coverage indicated that the core set represented the entire set well.

The detection, characterization and use of quantitative traits loci, QTL, have significant potential to improve the efficiency of selective breeding of species. Therefore, a population with 59 advanced backcross lines($BC_2F_5$), derived from a cross between IR64 and Tarome molaei, were studied in Tonekabon Rice Research Station of Iran in order to map QTLs for panicle length, number of grain per panicle, and panicle grain sterility in rice. The parental screening wtih 235 SSR markers in agarose and polyacrylamide gels revealed 114 markers with clear polymorphic bands. To search for QTLs associated with panicle length, number of grain per panicle, and panicle grain sterility, we constructed a genetic linkage map using 114 microsatellite markers. Positive and negative transgressive segregations were observed in $BC_2F_5$ lines for all traits. Using multiple interval mapping(MIM), a total of 20 putative QTLs were detected, of which eight were for panicle length, three for number of grains, and nine for panicle grain sterility. The maximum number of QTLs were mapped on chromosomes 1 and 2 with eight QTLs. These QTL markers could possible be utilized for marker-assisted selection.

The agronomic traits, such as days to flowering and maturity, plant height, 100-seed weight and seed filling period, are quantitatively inherited and important characters in soybean(Glycine max L. Merr.). A total of 126 $F_5$ recombinant inbred lines(RILs) developed from the cross of PI 171451$\times$Hwaeomputkong were used to identify quantitative trait loci(QTLs) for days to flowering(FD), days to maturity(MD), plant height(PH), 100-seed weight(SW), number of branches(NB) and seed filling period(FP). A total of 136 simple sequence repeat(SSR) markers segregated in a RIL population were distributed over 20 linkage groups(LGs), covering 1073.9 cM of the soybean genome with the average distance between adjacent markers of 7.9 cM. Five independent QTLs were identified for FD, three for MD, two for PH, three for SW, one for NB and one for FP. Of these, three QTLs were related to more than two traits of FD, MD, PH, NB and FP and mapped near the same positions on LGs H and O. Thus, these traits could be correlated with biologically controlled major QTLs in this soybean RIL population.

Worldwide, cyst nematode(Heterodera glycines Ichinohe) is the most destructive pathogen of cultivated soybean. In the USA, current annual yield losses are estimated to be nearly a billion dollars. Crop losses are primarily reduced by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars over time because resistance primarily traces to two soybean accessions. It is important to use diverse resistance sources to develop new nematode resistant cultivars. Soybean PI 494182 is a recent introduction from Japan and found to be resistant to multiple nematode populations. It is yellow seeded and maturity group 0. We have determined inheritance of resistance in PI 494182 using $F_{2:3}$ families derived from cross PI 494182 X cv. Skylla. Skylla is a susceptible parent. Three nematode populations, races 1, 3, and 5, corresponding to HG types 2.5.7, 0, and 2.5.7 were used to bioassay 162 $F_{2:3}$ families in greenhouse experiments. Based on Chi-square tests, a two-gene model is proposed for resistance to race 1 and a three-gene model is proposed for conditioning resistance to both races 3 and 5. Correlation coefficient analysis indicated that some genes conditioning resistance to races 1, 3, and 5 are shared or closely linked with each other. These results will be useful to soybean breeders for developing soybean cultivars for broad resistance to nematodes.

To assess the potential as biofortified rice varieties, new endosperm and grain mutant lines were selected from $M_4$ generation seeds of the rice cultivar Shindongjin, which were either $\gamma$-irradiated or treated with N-methyl-N-nitrosourea(MNU) and lipid, sugar, and tocopherol content were analyzed. Amylose content in non-waxy mutants ranged from 8.8% in SM-4, a dull-type mutant, to 29.5% in SM-51, compared to 18.9% in the parental variety, Shindongjin. SM-23, a floury-type mutant, contained 0.09 ${\mu}g/g$ $\alpha$-tocopherol(40.9% of total tocopherol), was three times higher than in the parental variety. SM-32, a giant embryo-type mutant, had a 2.2-fold higher total tocopherol content, 2.1-fold higher $\alpha$-tocopherol, and 5.5-fold higher $\delta$-tocopherol content(47.3% of total tocopherol) than the parental variety(0.13 ${\mu}g/g$). Total free sugar content was elevated in all selected mutants and 1.2-8.6 times higher than in the parental variety(11.38 ${\mu}g/g$). These increased sugar levels were due to increase in sucrose concentration. SM-23(floury-type mutant) and SM-51(high amylose-type mutant) had 4.6 and 7.0 times more sugar, respectively, than the parental variety(11.38 ${\mu}g/g$). With relatively high concentrations, most mutants showed elevated fatty acid content in the SM 32(giant embryo-type) and SM-51(high amylose-type) mutants, at 124.56 and 89.59 mg/g, respectively. All selected mutants displayed valuable characteristics for the development of new varieties in rice-breeding programs.

The effects of some coumarins(coumarin, 7-hydroxycoumarin, scopoletin and esculetin) were investigated on pumpkin(Cucurbita maxima Duch.) seedlings and on pumpkin glutathione S-transferases(GSTs). Coumarin and esculetin suppressed the growth of seedlings, especially the elongation of roots as well as hypocotyls. Among the compounds tested, only esculetin inhibited the activity of a particular pumpkin GST by 50%, CmGSTU3 toward 1-chloro-2, 4- dinitrobenzene(CDNB) and at a concentration of 22 ${\mu}M$. Both ethylacetae(EtOAc) and water fractions in pumpkin seedlings and different organs of one-month-old pumpkin plants contained esculetin or similar hydrophobic fluorescent substances as well as hydrophilic substances, which showed different degrees of inhibitory effects on CmGSTU3 activity.

To develop a natural re-seeding technology, the optimum soil incorporation time of Chinese milk vetch(CMV) plant residues, seed persistence in soil, biomass production and subsequent rice yield were determined from 2005 to 2007 in rice with CMV green manure in southern Korea. Generally, insufficient seedling stand was regenerated with CMV incorporation to the soil at 20 and 25 days after flowering(DAF), while high regeneration of greater than 400 seedlings per $m^2$ was observed at 35 and 40 DAF. High re-seeding stand of CMV incorporated at 35 DAF or later was related with high seed viability and heavy seed weight. Appreciable number of CMV seeds remained 4 month after burial in soil and a good number of CMV seedlings regenerated from this seed bank at rice harvest time in the fall. Based on the relationships among re-seeding number of CMV plants, seed weight and seed viability, CMV plants should be incorporated into the soil 35 DAF(May 30) or later when CMV seeds were sufficiently matured. The natural re-seeding stand for the 3-year trials was stable ranging from 437 to 700 plants per $m^2$ and the biomass production was sufficient to supply nitrogen for rice growth. The use of re-seeding CMV plant can produce similar rice yield like that of rice without CMV green manure.

Seed dormancy behavior of weed seeds is a critical determinant of their survival rates in a given cropping system as it helps the weeds to evade herbicides and other weeding practices. We investigated the effects of red light, alternating temperature, stratification duration and different doses of nitrogen containing compounds alone or in combination with red light on breaking seed dormancy of Chenopodium album L. The application of red light(80 ${\mu}mols^{-1}m^{-2}$) significantly increased seed germination of C. album in all treatments. Germination rates of 12 h incubated seeds were highest under 20 min of red light irradiation than 1 min, 5 min and 10 min treated seeds. Germination rate was significantly higher at alternating temperatures of $25^{\circ}C\;and\;5^{\circ}C$ for 12 h each with an irradiation of red light(80 ${\mu}mols^{-1}m^{-2}$) for 10 min than other treatments. Stratification period of 15 days significantly stimulated germination percentage of seeds incubated in dark, although 5 days of stratification along with red light application for 10 minutes exhibit similar effects on seeds. Seed germination was also enhanced by nitrogen containing compounds like $NaNO_2,\;KNO_3,\;NH_4Cl\;and\;NH_4NO_3$. We observed that seed germination increased significantly with 25 mM $KNO_3$ and 10 mM $NH_4NO_3$ in dark condition, while $NaNO_2$ and $NH_4Cl$ enhanced seed germination under red light irradiation. It was concluded that red light alone or synergized with alternating temperatures, stratification and nitrogen compounds, especially nitrite and ammonium enhanced seed germination of C. album. Thus, the red light can play a vital role in present and future weed management strategies.

Blast disease caused by the fungal pathogen, Magnaporthe oryzae, is one of the most damaging diseases in rice. The use of resistant varieties is an effective measure to control the disease, however, many resistant varieties were broken down to their resistance effects by the differentiating of new virulent isolates. This study was done to analyze the haplotypes of 31 microsatellite markers linked to five major R genes and two QTLs and to identify the alleles for the putatively novel genes related to durable resistance to blast in 56 Korean japonica and four indica varieties. The 31 microsatellite markers produced 2 to 13 alleles(mean = 5.4) and had PICi values ranging from 0.065 to 0.860(mean=0.563) among the 60 rice accessions. Cluster analysis based on allele diversities of 31 microsatellite markers grouped into 60 haplotypes and ten major clusters in 0.810 genetic similarity. A subcluster IV-1 grouped of early flowering varieties harboring Piz and/or Pi9(t) on chromosome 6 and Pita/Pita-2 gene on chromosome 12. The other subcluster V-1 consisted of four stable resistance varieties Donghae, Seomjin, Palgong and Milyang20. The analysis of putative QTLs associated with seven blast resistance genes using ANOVA and linear regression showed high significance to blast resistance across regions and isolates in the markers of two genes Piz and/or Pi9(t) and Pita/Pita-2. These results illustrate the utility of microsatellite markers to identify rice varieties is likely carrying the same R genes and QTLs and rice lines with potentially novel resistant gene.

Multilocation trials on 36 rice(Oryza sativa) genotypes of 3 different maturity groups were conducted at four different locations of Orissa for 3 years and 30 ragi(Eleusine coracana) genotypes of 2 different maturity groups were evaluated in three environmental conditions for 3 years. Grain yield data were subjected to stability analysis following linear regression model to estimate adaptability and stability parameters, i.e. b, and $S^2d$ Stability of performance of genotypes was also estimated by two other stability parameters viz., ecovalence W and AMMI stability value ASV. The rice and ragi genotypes of different duration groups showed wide variation in their mean yield, b, $S^2d$, W and ASV parameters. Seeds of the 36 rice and 30 ragi genotypes were treated with 500 and 100 ppm aqueous solution of maleic hydrazide(MH) for 24 hours, respectively to study MH-sensitivity. Sensitivity of genotypes to MH treatment was estimated in terms of seedling growth inhibition index(SGI). The rice and ragi genotypes showed wide differences in their MH-sensitivity in terms of SGI. Relationship of MH-sensitivity of genotypes with their yielding ability, adaptability and stability of performance was tested by contingency $x^2$ test. Low sensitivity of rice and ragi genotypes to MH in terms of SGI appeared to be good indicators of high yielding ability of genotypes. Also, low and high MH-sensitivity of genotypes would be a good indicator of better adaptability to rich and poor environments, respectively, in ragi but not in rice. Low MH-sensitivity of genotypes could be the good indicator of stability of yield performance in rice but not in ragi.