Abstract:

Objective: Under natural conditions, Quercus variabilis seeds have uneven emergence. This study monitored the characteristics of seed germination and emergence of Q. variabilis day by day, explored the characteristics of seed germination and emergence of Q. variabilis and its own physiological and biochemical change process, analyzed the mechanism of irregular emergence, and provided theoretical support for accurate regulation of seedling quality. Method: Through the dynamic observation of the germination and emergence process of Q. variabilis seeds, according to the characteristics of seed morphological changes and emergence statistics during the germination and emergence process of Q. variabilis seeds, the germination and emergence process of Q. variabilis seeds was divided into stages and periods, and the physiological and biochemical changes of Q. variabilis seeds germinated and emerged at different stages and periods were measured, The activities of peroxidase (POD) and superoxide dismutase (SOD) were determined by plant physiological method, the contents of gibberellin (GA₃), indoleacetic acid (IAA) and abscisic acid (ABA) were determined by high performance liquid chromatography, and the contents of soluble sugar and starch were determined by anthrone colorimetry, α- amylase and β- amylase was determined by 3, 5-dinitrosalicylic acid colorimetry. Result: 1) Q. variabilis seeds began to germinate on the 6th day after sowing, and ended on the 33rd day. The germination cycle was 27 days, and the cumulative germination rate was 73.6%, of which the median germination was 14 days. Q. variabilis seeds began to emerge on the 21st day after sowing and ended on the 60th day. The emergence cycle was 40 days, and the cumulative emergence rate was 66.6%, of which the median emergence was 29 days. The emergence process of Q. variabilis seeds can be divided into three periods. When the average daily emergence rate of Q. variabilis seeds exceeds 3%, it is the emergence peak (25-30 days after sowing), which accounts for 10% of the whole emergence cycle. During this period, the number of seedlings accounts for 44% of the total number of seedlings; Before this period, the emergence stage is the rising stage (1-24 days after sowing), accounting for 40% of the whole emergence cycle, and the number of emerging seeds accounts for 11% of the total number of seedlings; The peak period is followed by the emergence decline period (31-60 days after sowing), accounting for 50% of the whole emergence cycle, and the number of emergence seeds accounts for 45% of the total number of emergence. 2) In the process of Q. variabilis seed germination, the POD activity in the first germinated Q. variabilis seed is higher. In the process of Q. variabilis seed emergence, the pod and SOD activities in the seed are higher when the number of seeds is large. 3) Compared with germinating seeds, GA₃ increased by 64%, ABA decreased by 30.3%, soluble sugar content decreased by 51% and starch content decreased by 24.1%, α-amylase activity decreased by 45%, while β- amylase activity increased by 67.7%. Conclusion: The germination and emergence of Q. variabilis seeds are two independent processes, and some seeds have germinated but not emerged in the end. The long period from seed germination to seedling emergence and large individual differences are the main factors leading to uneven seedling emergence of Q. variabilis while seed dormancy of Q. variabilis is different among individuals, and the seed germination cycle is long, which is also one of the reasons for the uneven emergence of Q. variabilis seeds; POD and SOD mainly affected the germination stage of Q. variabilis seeds; GA₃ and IAA promoted the emergence of Q. variabilis seeds. The higher the content, the faster the emergence rate; ABA inhibited the emergence of Q. variabilis seeds.

Key words: Quercus variabilis, seeds, germination, emergence of seedlings, enzyme activity, endogenous hormone