Screening technique for salinity tolerance at reproductive stage in rice
2004
Islam, M.M. | Gregorio, G.B.,International Rice Research Inst., DAP Box 7777, Metro Manila (Philippines). Plant Breeding, Genetics and Biochemistry Div. | Barrion, A.A. | Mendoza, R. | Adorada, D.
Salinity tolerance at reproductive stage is the most important trait for rice because yield reduction is the ultimate determining factor for tolerance. An experiment was set up to evaluate the effect of salinity on yield and yield components at different growth stages of rice using plastic pots with holes on salinized water bath. Five varieties with known reaction to salinity stress were chosen for this experiment. Pokkali (tolerant), PSBRc 50 (moderately tolerant), PSBRc 86 (moderately tolerant), IR64 (moderately susceptible) and IR29 (susceptible). Set-ups were salinized at electrical conductivity (EC) level 8 dS/m after 30, 50, 63 and 82 days of sowing at tillering, panicle initiation, flowering and grain filling stages, respectively. Salinity was maintained for two weeks at each stage and desalinized back to normal. Results showed no significant differences in plant height at all growth stages. Rice under normal condition produced more green leaves than salinized plants at all stages. The greener the leaves the higher the photosynthesis and produced higher yields. Salinity had negative impact on yield components including number of panicles, number of tillers, spikelets/plant; floret sterility and individual grain size. Delayed heading were observed in all salinized set-ups. There was no clear evidence that tolerance at one stage implies tolerance at other stages, and the response of rice to salinity can vary greatly with stage of development. F8 recombinant inbred lines (RIL) mapping population of the cross IR29 x Pokkali are now being used to tag the genes responsible for salinity tolerance at reproductive stage.
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