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

【Objective 】The 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. 【Method 】The 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. 【 Result 】 The 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 improvement in resistance to bacterial leaf blight of 100 hybrid rice varieties during 2003-2014. The comprehensive index of resistance to Ⅳtype andⅤ type of Xanthomonas oryzae pv. Oryzae ranged from 6.33 to 7.75 and from 7.00 to 9.00, respectively. The index of Ⅳ type was lower than that of Ⅴtype in each year. Furthermore, 44 hybrid varieties were derived from male sterile line Bo A combining with different restorers, which was account for 44%; while other 56 varieties were derived from 35 sterile lines, which was account for 56%. For rice blast, there were no significant differences in resistance indices between the hybrids derived from Bo A combinations and the other male sterile lines ' combinations during 2003-2007, and all of them ranged from 8.00-8.75. While the resistance indices of hybrids derived from Bo A combinations were higher than those of the other male sterile lines ' combinations during 2009-2014. No significant differences were found in resistance to bacterial leaf blight between these hybrids derived from different combi-nations. 【 Conclusion 】 The 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 enhancing disease resistance level in Guangxi rice breeding.