关键词: 油松, 种子萌发, 呼吸代谢, 酶活性

Abstract:

The seeds of Pinus tabuliformis were cultivated at (25±1) ℃ in an incubator and the respiratory rate, activities of PGI, MDH and G-6-PDH and 6-PGDH of the seeds were measured to investigate changes in respiratory intensity and pathways during the initial germinating stages. The results showed that changes in the respiratory rate could be divided into three stages:rapid increase,stagnation and rapid increase again. The rapid increase stage occurred at the first 27 h,and the respiratory rate rose from 0.5 μmol·g^-1min^-1 to 12.79 μmol·g^-1min^-1. Within the following 18 h,respiratory rate was basically stable ranged from 12.79 to 13.55 μmol·g^-1min^-1. After 45 h incubation,the seed respiratory rate rapidly increased again. When the radicle emerged, the second peak value of respiration was 20.23 μmol·g^-1min^-1. Activities of all respiratory enzymes increased during the initial germinating stages. The PGI activity increased rapidly and reached to the maximal value of 52.25 OD·g^-1DW in 27 h, and then decreased rapidly. MDH activity did not change obviously in the first 36 h, and afterwards increased to a peak value of 30.84 U·g^-1min^-1 in 72 h. The G-6-PDH and 6-PGDH activity increased slowly from 21.6 U·g^-1min^-1 to 29.04 U·g^-1min^-1 in the first 36 h, thereafter, the activity increased rapidly and reached to a peak value of 57.9 U·g^-1min^-1 with radicle emergence. In conclusion, respiratory metabolism pathways at the early stages of incubation were mainly EMP and PPP,especially EMP pathway. Whereas,during the late stages,EMP, TCA and PPP pathways coexisted,and PPP pathway was predominant.

Key words: Pinus tabulaeformis, seed germinating, respiratory metabolism, enzyme activity