Toleransi Varietas Padi terhadap Salinitas pada Fase Perkecambahan
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Salt tolerance of r i c e plant (Oryza sativa L.) varies among v a r i e t i e s a s well as among growth stages. Laboratory and greenhouse experiments were conducted t o study the v a r i e t a l tolerance during the germination and the seedling stages. The seeds of PB 28 and PB 32, susceptible and tolerant varieties , respectively, were germinated i n petridishes with f i l t e r paper saturated with 0, 0.25, 0.50, 1.00, 2.00, and 4.00 % (W/V) NaC1. The germinating seeds were transplanted to soil culturesalinize d with 0.30 % NaC1. The seeds unable t o germinate i n 10 days were throughly washed t o remove the N a C l and then were germinated in petridishes with filter paper saturated with water. High eoncentrations of NaCl reduced both the germination r a t e and the number of germinating seeds. Low concentrat ions, however, only reduced the germination rate . Not all of the nongerminating seeds could germinate after the washing, indicating a toxic effect of NaC1. Salt concentration did not affect water absorption during the f i r s t two days, but decreased the absorption t h e r e a f t e r . Water absorption was s i g n i f i c a n t l y correlated (P < 0.01) with the s a l t concentration ( r = -0.8782) , the r a t e of germination ( r = 0.9476), and the number of germinating seeds ( r = 0.8669). It was not possible to detect significant varieta1 differences in salt tolerance based on the number of germinating seeds, germination rate , water absorption, dry weight of three-week-old seedlings , or the surviving seedling percentage. Significant differences (P< 0.05) were observed between the two varieties based on the percentage of seeds t h a t germi-nated on water-saturated paper following the 10-day salt treatment. The screening of breeding material for salt tolerance can be done during germination, ietreating the seeds with 2.00 % NaCl for 10 days, and then determining percentage germinat ion on water-saturated paper. However, further experiments should be conducted toverify the finding.