A population of 120 double-haploid lines derived from Samgang/Nagdong was used for analyzing the developmental behaviors of plant height and tiller number by conditional mapping via composite interval approaches at five growth stages of rice. The traits were normally distributed with transgressive segregations in both directions. A total of 4 QTLs associated with plant height were identified in 40th/initial, 50th/40th and 60th/50th periods, respectively. The qph7.1 was observed in 50th/40th and 60th/50th periods, with increasing effects from Samgang and Nagdong alleles, respectively. This indicated that an individual gene or genes at the same genomic region might have opposite genetic effects at various growth stages. Five QTLs associated with tiller number were identified in four stages except 60th/50th stage. Four of five increasing effects of QTLs were from Nagdong alleles. Six of nine QTLs for two traits were detected before 60 days. It was evident that the expression of QTLs for plant height and tiller number was more active at early stages than at maturity stage. Furthermore, QTLs identified at early stages showed opposite additive effects on plant height and tiller number. These results provided a possible genetic explanation for the negative correlation between two traits.

This study was conducted to investigate the occurrence of Soil borne wheat mosaic virus(SbWMV) in barley fields in Korea and to examine the host pathogenicity of SbWMV. By using the ELISA test, SbWMV was detected in the six regions : Suwon, Milyang, Jinju, Youngkwang, Iksan, and Chonju. SbWMV was isolated from the two strains, Albori strain from Jinju and Eunpamil strain from Milyang. SbWMV was collected from leaves showing mosaic, yellowing and necrosis stripes. SbWMV was inoculated mechanically on 1∼1.5 leaf stages with leaf-rubbing to identify the host pathogenicity of 36 Korean barley cultivars, a wheat cultivar, two rye cultivars, three Japanese barley cultivars and Chenopodium amaranticola. Viral sympoms of inoculated leaves appeared on moulted loaves about 4 to 6 weeks of inoculation. Baegdong and Tapgolbori, infected from Albori strain and Eunpamil strain infected from Samdobori showed much higher susceptibility than C. amaranticola and C. quinoa which showed ring spots and chlorotic spots respectively. Virus particles were observed by the electron microscope. They were rod-shapes, which are bipartite, of 142 nm or 281 nm in length with 20 nm diameter on infected leaves. Specific detection and identification of SbWMV was set up using the RT-PCR. PCR fragments of SbWMV(0.5kb) were obtained by using the designed primers for SbWMV RNA 2.