Cryopreservation of dormant Prunus armeniaca L. seeds

The techniques to break dormancy and feasibility of cryopreservation were investigated using freshly collected fully mature Prunus armeniaca seeds (true seeds + endocarp) from Xinjiang province, China. No seeds germinated at the time of collection when incubated at 20/25°C for five weeks. The endocarp was permeable to water, thus dormancy was not due to an impermeable coat, i.e physical dormancy. Manual removal of endocarps (half-seed) resulted in germination of 10% of seeds without any other treatment. Gibberellic acid treatment improved germination in 66-83% of the half-seeds and cold-wet stratification relieved dormancy in 69-80% of half-seeds. Thus, seeds have non-deep to deep physiological dormancy. Drying half-seeds to water content of 3.3% f.w.b. did not lead to viability loss confirming the orthodox nature. Half-seeds dried over silica gel (4.1% f.w.b.) survived better compared to air dried samples (7.8% f.w.b.) following liquid nitrogen storage. Although storing dormancy broken seeds in liquid nitrogen resulted in lesser germination percentage after six months of storage compared with the dormancy broken at the end of storage, this effect was not statistically significant (P > 0.05). Our results demonstrate seeds of P. armeniaca can be stored in liquid nitrogen for conservation purposes.