Effect of pre-soaking treatments and temperature on seed germination of guava (Psidium guajava']java L.)

The effect of various pre-soaking treatments (soaking in distilled water (DW), GA(3) 100, 500 and 1000 ppm for 24 and 48 h and HCI (35%) for 3 and 5 minutes) and temperature (constant - 32 degrees C for 24h and alternating temperatures of 32/29 32/25 and 32/20 degrees C for 6/18h) on promotion of seed germination in various guava accessions (EC147037, EC14039, EC147036 and EC 162904) was tested. Among the pre-soaking treatments soaking in DW followed by GA3 for 48 h was found superior whereas soaking in HCI (35%) for 5 minutes inhibited germination significantly. Alternating temperature of 32/20 degrees C resulted in maximum (100%) germination when compared to other temperature conditions. The magnitude between upper and lower temperatures in the alternating temperature range also affected seed germinability. When the temperature range was from 32 to 20 degrees C, all accessions demonstrated maximum germination, but when temperatures ranged from only 32 to 29 degrees C, germination of most of the accessions was lower, and closer to that when temperature was a constant 32 degrees C.