Population dynamics of Xanthomonas oryzae pv. oryzae in cultivars with different levels of resistance

Abstract

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is one of the most destructive diseases of rice in majority of the rice growing countries especially in Asia. As the chemical control of this disease is not very successful, greater emphasis has been given on host plant resistance. In the present investigation, rate of multiplication of Xoo was observed in three different rice varieties having different levels of resistance against BB viz., TN1 (susceptible), Ajaya (moderately resistant) and Improved Samba Mahsuri (ISM) (resistant). The results revealed that rate of multiplication was faster in susceptible TN1 after 5th day, population shot up at POI in TN1 and gradually decreased after 7th day probably due to the rapid death of leaf tissue and unavailability of nutrients, and however the movement of the bacteria was also high in TN1 when compared to other two varieties Ajaya, Improved samba mahsuri. However, there were significant differences in Xoo population at 1 cm below POI. At 1 cm below of POI, Xoo multiplied rapidly in TN1 compared to resistant variety, ISM.