Wild Rices , Oryza rufipogon, a Source of Resisitance to Root-knot Nematodes in rice

Abstract

A wild rice collected from Khon Kaen Rice Experiment Station in 1986 was identified into the species of Oryza rufipogon by Songkran Chitrakorn. It was used as female parent to cross with cultivars in 1987 for studying its benefit genotypes. The F4 lines having cultivar characters SPR 871-1 to 12 from the cross SPR 871 (RD7/O. rufipogon) were tested in the naturally infested soil with Melodogyne graminicola for the reactions of the rice plants to root-knot nematodes under screenhouse conditions of Pathumthani Rice Research Center in October-December 1990.
Each testing line, resistant check (Khao Dawk Mali 105) , and susceptible check (Leuang Rai, and Taichung Native 1) were seeded in a row of 100 cm in length with a spacing of 5 cm between hills and 10 cm between rows. The test was replicated for 2 replications, and each row of testing lines was also randomized within each replication. Twenty days after seeding, the testing plants were put into drought stress by stop watering for 20 days. After watering was resumed for 10 days that the testing lines also reached 50 days old, the number of root knots and roots per plant was counted, and the longest root of each plant was measured. Results suggested that the F4 lines except SPR 871-1, wwere resistant to root-knot nematodes.
Since RD 7 had been tested proviously by Leuchai Arayarungsarit from Pathumthani Rice Research Center, RD7 was recognized as moderately susceptible to M. graminicola, Consequently, the resistant genotypes to root-knot nematodes as expressed in the F4 lines from teh cross SPR 871 must come from teh O. rufipogon.