Sintered composites of Al-8wt%Cu-10vol%SiCp were deformed by repressing or equal channel angular pressing(ECAP) at room temperature, and . Repressing produced more densification than ECAP but resulted in much lower transverse rupture strengths. In both cases, deformation at room temperature and , resulted in much lower strengths than deformation at , and also caused the fracturing of some SiC particles. The higher bend strengths and less SiC fracturing at are attributable to the presence of an Al-Cu liquid phase during deformation. The employment of copper coated SiC instead of bare SiC particles for preparing the composites was found not improving the properties.

Molecular markers are useful tools for evaluating genetic diversity and determining cultivar identity. Present study was conducted to evaluate the genetic diversity within a diverse collection of rice accessions used for Korean breeding programs. Two hundred eighty-seven rice cultivars, composed of temperate japonica, tropical japonica, indica, and Tongil-type of Korean crossing parents were evaluated by means of 15 simple sequence repeat (SSR) markers. A total of 99 alleles were detected, and the number of alleles per marker ranged from 4 to 11, with an average of 6.6 per locus. Polymorphism information content (PIC) for each of the SSR markers ranged from 0.2924 to 0.8102 with an average of 0.5785. These results, with the result that use of only 15 SSR markers made all rice cultivars examined could be uniquely distinguished, imply the efficiency of SSR markers for analysis of genetic diversity in rice. Cluster analysis was performed on similar coefficient matrics calculated from SSR markers to generate a dendogram in which two major groups corresponding to japonica (Group I) and indica and Tongil type rice (group II) with additional subclasses within both major groups. The narrowness of the Korean breeding germplasm was revealed by the fact that most of the Korean-bred and Japan-bred temperate japonica cultivars were concentrated into only 2 of the sub-group I-1 (143 cultivars) and I-2 (58 cultivars) among six sub-groups in major group of japonica. This is because of the japonica accessions used in this study was a very closely related ones because of frequent sharing of the crossing parents with similar genetic background with synergy effect of the inherited genetic difference between indica and japonica. A rice breeding strategy with the use of molecular markers was discussed for overcoming of genetic vulnerability owing to this genetic narrowness.

If a quantitative trait loci (QTL) marker identified in a population is applicable to different populations (marker universality), this will not only reduce the labor and cost in marker assisted selection (MAS), but accelerate the application of molecular markers to real breeding programs. Present study aims to evaluate the defined QTL related markers from a population to a different breeding population for the MAS. Four rice breeding populations were subjected to seventy-five simple sequence repeat (SSR) markers which were already identified for their polymorphism information content (PIC) in the parents of the crossings. Among them, eight markers were evaluated for their correlation between presence of marker alleles and phenotypic expression in breeding populations. A reasonable level of polymorphism for the mapped markers originated from any sources of rice accessions was observed between crosses of any sources (marker repeatability). However, correlation between presence of markers and expression of the traits in rice breeding populations was not significant except for minor portion of traits and markers examined (failure of marker universality). In the present study, various strategies were discussed to develop new markers with universality of breeding application.

The heading date is known to be controlled by two kinds of genetic constituent, photosensitivity and basic vegetable phase. For the latter, the effect of temperature in early growth period is critical to determine the shortness of vegetative growth periods in plant's life. A phytotron experiment on 55 rice cultivars, consisting of two ecotypes of rices, indica and japonica, was conducted at high and low temperature treatments at early growth stage to investigate the possible role of plant growth stimulus by high temperature to associate with shortening of heading date. The high temperature during the early growth stage stimulated the rice growth as measured by plant height with much difference of the growth response between indica and japonica. The conclusive finding that these growth stimulus in early growth stage was highly correlated with the acceleration of heading is, more or less, correlated with the heading of the late growth stage although we could not conclude the genes for early plant growth stimulus by high temperature is the same genes as the genes for accelerating of heading in the late growth stage of plants.

One of the most attractive short-term possibilities for increasing freezing tolerance of winter crops may be the application of chemicals. This research was conducted to determine the effect of two plant growth regulators. Terpal-C and Cerone on freezing tolerance and winter survival of canola. Three cultivars were planted on the michigan state University Agronimy Farm at East Lansing. MI. on Sept. 10. 1992 and 1993 Chemicals were applied to one-month-old plants when they reached the 5 leaf stage. Ion leakage tests for freezing tolerance were conducted before and after chemical treatment. Winter survival was evaluated by counting the plant standing in the fall and spring. Neither of the chemicals. Terpal-C. inhibited natural cold hardening.