EFECTS OF STRATIFICATION AND TEMPERATURE ON THE GERMINATION OF <em>DALBERGI</em> <em>COCHINCHINENSIS</em>, <em>PINUS <em>KESIYA</em> AND <em>PINUS</em> <em>MERKUSII</em>

Abstract

The effects of stratification and incubation temperature on seed germination were investigated for Dalbergia cochinchinensis, Pinus kesiya and Pinus merkusii. Seeds were either soaked for 24 h, or stratified (soaked in water for 24 h and stored at 2 - 5 °C) for 2 weeks, then incubated for 21 days at 30/20 °C, 30 °C, or 20 °C. Germination test results were compared to results of two rapid viability tests, X ray and tetrazolium chloride (TZ). This information will assist in determining the true potential of seeds used for reforestation and facilitate nursery operations in tropical countries where D. cochinchinensis, P. kesiya, and P. merkusii are grown. Total germination of D. cochinchinensis was greater when seeds received no stratification treatment. Of the three incubation temperatures, germination was most rapid when seeds were incubated at 30 °C, but highest when seeds were incubated at 30/20"C. Stratification enhanced germination rates of P. kesiya and P. merkusii under all incubation temperatures. Temperature also enhanced the speed of germination; germination was most rapid when the seeds were incubated at 30 °C, and slowest when incubated at 20 °C. For D. cochinchinensis, germination test results agreed well with results of X-ray tests, but poorly with TZ tests. Both X-ray and TZ tests corresponded well with germination tests of P. kesiya, but neither quick test correlated well with germination test results of P. merkusii. The poor correspondence may have been due to the relatively low quality of the P. merkusii seed source used in this study, and further refinement is needed for this species. Nevertheless, the use of X-ray and TZ quick tests appears feasible in those instances when there is insufficient time available for a standard test.