Lipolytic activity and chilling requirement for germination of some almond cultivars
Traditionally, cold stratification for three weeks is commonly used for almonds (Prunus amygdalus Mill.) seeds germination. In this study, the effect of cold stratification in two almonds varieties: ‘‘Achaak’’ a Tunisian cultivar and ‘‘Tuono’’ an Italian cultivar was tested. The study revealed, for the first time, that only the Tunisian cultivar ‘‘Achaak’’ was able to start up its germination after 16 h of imbibition, at 26°C without any previous chilling. In these conditions, (i) hypocotyl elongation was not affected compared to the Controls, suggesting that the cold requirement of a seed is an adaptation to climatic factors; (ii) the ability of germination of 5-year-old Achaak seeds was not totally affected; (iii) the partially purified lipase showed a true neutral activity, detected at the 3-day-old germinating step. This is the first published data regarding the almond lipase identification.
Key words: Germination, imbibition, stratification, chilling, triacylglycerol lipase, Prunus amygdalus Mill.