Straighthead and Agronomy Characters Testing for Selected Parent Lines and Hybrid Combinations at UAPB in 2011-2012

Abstract

Straighthead disease is a physiological disorder in rice and the most widespread non-fungal disease of the U.S. straighthead greatly reduces rice yield. Straighthead studies were most conducted in the artificial field which was Arsenic amendment plots due to the similarity of straighthead symptoms of Arsenic damage. To evaluate the straighthead disease resistance in natural condition, 46 rice lines, including 24 inbred lines and 22 hybrid combinations which were developed from breading program, were chosen for straighthead and agronomy characters testing in a native soil where straighthead naturally induced in the past years at University of Arkansas at Pine Bluff (UAPB), Arkansas in 2011 and 2012. The straighthead of rice were rated from 0 to 9 levels, and 0 was the least straighthead disorder and 9 was the most severe straighthead disorder. Cocodrie (CCDR) was used as the check in this study. The results of 2011 showed that the yields of 8 entries were higher than the check CCDR. The straighthead scores of these 8 entries were 0 - 1 which indicated their resistance to straighthead. The rest of the entries had lower yields than check CCDR with straighthead scores 5 - 6 which indicated their moderate susceptibility to straighthead. The yields were negatively related to the straighthead scores (r = - 0.9178, P < 0.01). The results of 2012 showed that the yields of 9 hybrids and 6 inbred entries were higher than the check CCDR. The straighthead scores of top 12 entries were 0 - 2 which indicated that they were resistant to straighthead and 3 entries with straighthead score of 3 which indicated they were moderately resistant to straighthead. The rest 3 hybrids and 4 inbred entries had lower yields than the check and their straighthead scores were 5 - 6 which indicated their moderately susceptible to straighthead. The yields was negatively related to the straighthead scores (r = -0.956, P < 0.01). Compared to CCDR, the yield of hybrids showed their straighthead resistance at some extent. The yields of top six entries, hybrid 33A/PB23, inbred 3053, hybrid 28s/PB22, 28s/PB24, 29s/PB24 and inbred 3222, were 10,376.4, 9991.4, 9566.7, 9334.3, 9183.9 and 9174.3 Kg/Ha, and 46.0%, 40.7%, 34.7%, 31.4%, 29.3%, and 29.5% higher than the check, respectively.