Studies on rice seed inspection of bacterial leaf streak of rice: II. Rice leaf in vitro method.

Abstract: A series of rice seed inspection technique by rice leaf in vitro test for Xanthomonas campestris. pv. oryzicola were established after 3-year studies. With the method 44 samples of natural infected rice seeds of bacterial leaf streak were successfully inoculated onto the rice leaves in vitro, and produced lesions and bacterial beads on them. The method reveals young rice leaves in vitro on 1% water agar with 90 ppm of benzimidazole in petri dishes maintains green for 15-20 days under saturation of relative humidity, light of flurescent lamps at days or nights and temperature of 30℃, which satisfies the needs of the time for induction of lesions and bacterial beads. Due to these suitable conditions, concentration suspension of the samples of diseased seeds in weight of 1.2-4.0g can be inoculated onto young rice leaves in vitro with an insect needle, the lesions and bacterial beads appeared at 3 days and 5.5-8.5 days after inoculation respectively. The lowest concentration of the pure culture for the symptom induced is 5×10~3 cells/ml in this method.