|Webster James A,|
Submitted to: Crop Science
Publication Type: Germplasm Release
Publication Acceptance Date: July 31, 1994
Publication Date: N/A
Interpretive Summary: This article registers STARS-9301B barley germplasm which was formally released by USDA-ARS in June 1993. No new research results are reported; interpretive summary not required.
Technical Abstract: STARS-9301B is a 6-rowed spring barley germplasm developed as a source of resistance to the Russian wheat aphid (RWA). This line is a selection out of PI 366450. Although nearly homogeneous for RWA resistance, it did segregate for height gene(s). Plants were selected for RWA resistance and medium plant height, and progeny were evaluated for RWA resistance before seed was bulked for release. This germplasm is highly resistant to RWA whe tested as seedling plants under controlled greenhouse conditions. This resistance persisted when plants are grown to maturity in the greenhouse under constant RWA infestation at levels 100 times greater than natural field infestation. RWA-infested leaves of STARS-9301B develop normally, while leaves of susceptible plants are rolled, which traps the awns of emerging spikes. This interferes with seed set and development and results in yield reduction. The flat leaves of STARS-9301B reduces the yield- limiting effects of rolled leaves typical of RWA feeding. Results of field studies under natural RWA infestations confirmed the high level of RWA resistance of STARS-9301B detected in greenhouse tests. Yield reduction due to tiller loss does not occur in STARS-9301B. Genetic analysis of parent, F1, F2, BC1F1, and F3 populations of th3 cross 'Morex'/STARS-9301B indicate that 2 genes are responsible for resistance in this line. Chi-square analysis of F2 and BC1 to either parent suggests mutual epistasis between 1 additive gene and 1 dominant gene. STARS-9301B is similar to Morex in plant height and only slightly later than Morex in maturity in greenhouse studies, as well as in diverse field locations ranging from Colorado to sourthern Canada. Resistance is primarily tolerance with antibiosis secondary.