Main disease resistance and breeding tendency of photosensitive hybrid rice varieties registered in Guangxi during the past decade

ObjectiveThe present study were conducted to analyze the main diseases ’ resistance performance and developing trend of photosensitive hybrid rice varieties registered in Guangxi during the past decade , in order to provide references for disease resistance breeding. MethodThe resistance to rice blast and bacterial leaf blight of 100 photo-sensitive hybrid rice varieties , which were registered in Guangxi from 2003 to 2014 , were analyzed according to the data came from Guangxi rice regional trials . ResultThe results showed that , the average comprehensive resistance index of rice blast showed a decreasing tendency during the past decade; it ranged from 7.92-8.75 during 2003-2009 and 6.61-7.50 during 2010-2014, and the lowest one (6.61) was observed in 2012. There was no obvious improve-ment in resistance to bacterial leaf blight of 100 hybrid rice varieties during 2003-2014. The comprehensive index of resistance to Ⅳtype andⅤtype of Xanthomonas oryzae pv. Oryzae ranged from 6.33 to 7.75 and from 7.00 to 9.00, re-spectively. The index of Ⅳ type was lower than that of Ⅴtype in each year. Furthermore, 44 hybrid varieties were de-rived from male sterile line BoA combining with different restorers , which was account for 44%; while other 56 vari-eties were derived from 35 sterile lines , which was account for 56%. For rice blast , there were no significant differ-ences in resistance indices between the hybrids derived from BoA combinations and the other male sterile lines ’ combi-nations during 2003-2007, and all of them ranged from 8.00-8.75. While the resistance indices of hybrids derived from BoA combinations were higher than those of the other male sterile lines ’ combinations during 2009-2014. No sig-nificant differences were found in resistance to bacterial leaf blight between these hybrids derived from different combi-nations . ConclusionThe resistance to rice blast of photosensitive hybrids registered in Guangxi improved gradually during the past decade , while no significant improvement was found in bacterial leaf blight. Therefore , the resistance breeding for rice blast should be strengthened in future. Meanwhile , more emphasis should be given on resistance breeding for bacterial leaf blight. It is important to enrich the genetic background of photosensitive hybrid rice for en-hancing disease resistance level in Guangxi rice breeding.