Possible Causes of Poor Germination of Large Cardamom Seeds
P. P. Khatiwada and A.J. Murdoch
Department of Agriculture, the University of Reading
Early Gate, Reading, RG6 2AT, Berkshire, United Kingdom
(Presently: Agriculture Research Station, Pakhribas, Dhankuta)
This paper reports on studies which were conducted to find out the reason(s) for the poor and irregular germination of large cardamom seeds including possible hardseededness, poor oxygen exchange, the presence of inhibitors, embryo immaturity or of a combination of these reasons. Poor (< 5 percent) germination was found in seeds even after a six month germination test at 20/30⁰C (16h/8h). Viability also dropped to 50.7 percent from 85.3 percent during this test. Similarly no seeds germinated over a shorter period (10 weeks) even after the application of dormancy-relieving treatments to seeds over 80 percent of which were viable. The seed coat did not greatly impede inhibitions of water. The moisture level in seeds increased from 16.1 percent to 37.8 percent in unrubbed seeds and 39.9 percent in individually rubbed seeds in 24 hours. Mechanical scarification (rubbing) treatment was found to be detrimental to the seeds. No germination and 100 percent decay were found in individually rubbed seeds during an 18 week germination test compared to 32 percent in the unrubbed control. Elongation of the linear embryo during warm stratification suggested that embryo immaturity is one possible reason for dormancy in large cardamom. The embryo grew at the rate of 0.08 mm per week at 25⁰C but was 16.2 percent slower at 35⁰C. The warm stratified seeds did not, however, germinated in a 10 week test and indeed some loss of viability occurred. Further work on warm stratification is recommended but at a temperature lower than 25⁰C to avoid loss of viability. Similarly, temperature regimes other than 20/30⁰C and 5/25⁰C (8h/16h) are advised for germination tests.