In 1995, development of the second-generation NPT lines was begun by crossing the first-generation tropical japonica NPT lines with elite indica parents.
Indica parents have effectively increased tillering capacity and reduced panicle size (i.e., number of spikelets per panicle)
in the second-generation NPT lines.
Indica germplasm also helped improve other NPT attributes such as grain quality and disease and insect resistance.
Some second-generation NPT lines (F5 generation) were planted in a replicated observational trial for the first time in the 1998 wet season. Overall, the second-genera-tion NPT lines showed yield advantage over the first-gen-eration NPT lines.
A rigorous comparison between the second-generation NPT lines and indica inbred varieties is needed, however, to determine the progress of improving rice grain yield by NPT breeding.