Cephalotaxus fortunei seed-physiological changes and differences among three seed sources during low temperature priming

Key words: 
• botany /
• Cephalotaxus fortunei /
• seed /
• seed source /
• dormancy-breaking /
• low temperature priming /
• physiological mechanism

Abstract: Cephalotaxus fortunei seeds from three seed sources, namely Liping,Guizhou Province;Mingxi,Fujian Province; and Yanyuan, Sichuan Province, were used to determine physiological changes during low temperature priming(direct sand storage in 5℃ for 10 days, 20 days or 30 days)as well as variation among seed sources by measuring fattiness, amylum, amino acid, POD(peroxidase), CAT(catalase), IAA(indoleacetic acid), GA3(gibberellin), ABA(abscisic acid) and ZR(zealin) concentrations in seeds. Results after low temperature priming indicated that the average germination rate of Liping seeds(30.9%) was greater than Mingxi seeds (9.9%)and Yanyuan seeds(1.9%). Of the different treatments, the 10 days low temperature priming had the highest seed germination rate. In addition, during low temperature priming, active metabolism, decreased levels of fat and starch, increased amino acids, and enhanced POD CAT activity were detected. In the endosperm, seeds fromMingxi possessed lower levels of ABA after low temperature treatmentwith no obvious change or little increase of GA3 ABA ratio.Thismightbe one reason for seed dormancy-breaking. In spite of a lowABA content and a high GA3 ABAratio in the endospermof Yanyuan seedsbefore lowtemperature priming,germination did notoccur;ABA in the seed endospermincreased mostly after lowtemperature priming.This indicated thatwith Yanyuan seeds some unknown factors controlled seed dormancy; also, the lack of germinationwith lowtemperature primingmightbe the result of a long adaptation to warmerwinters in Sichuan.Moreover, the low germination rate of seeds fromMingxi with direct sand storage seemed to be related to high ABA content in the endosperm.[Ch, 5 tab. 8 ref.]