whereas the recipient parent and the susceptible cultivar TN1 were
completely susceptible to the BPH (Fig. 4).
Under free choice conditions in the AFP test, the settling
response of BPH initially was not significantly different on all
cultivated rice. The number of BPH on RH and resistant IL plants
were significantly lower than TN1, susceptible IL and KD plants
after 24 h of infestation. The BPH nymphs were first randomly
landed on all rice plants and started to move to the susceptible
plants increasingly after 24 h of infestation. The number of BPH
nymphs settled on the susceptible plants remained significantly
higher and was found increasing after 72 h (Fig. 2).
To validate the level and broad spectrum of resistance against
BPH populations collected in Thailand, the selected lines were
evaluated at the seedling stage using SSBS. Six BPH populations
were selected based on its variations from the previous study
(Jairin et al., 2007a). All selected lines carrying Bph3 showed
resistance to all BPH populations (Table 3). The result indicated
that a broad spectrum BPH resistance gene which has been
introgressed from RH to KD was effectively against the variation of
BPH populations found in Thailand.