The effect of low temperature during germination stage on seeds germination characteristics of 12 cultivars of spring rapeseed (Brasicca napus L.)

摘要

An experiment was performed in 2005 in the seed laboratory of Tehran University to study the effect of low temperature during germination stage on seeds germination characteristics of 12.cultivars of spring rapeseed. The experimental design used for this study was factorial in the form of randomized completed design with four replications. Treatments were consisted of first factor in two levels: l-germination in standard conditions.2-germination with coldness as a pretreatment. Second factor was 12 cultivars of spring rapeseed. Germination in standard conditions was done at 25°C and for performing coldness pretreatment;seeds in swelling form were set within a period of 5.days at.5°C temperature and then transferred to 25°C temperature. In the basis of the results, the effect of germination conditions was significant on seedling dry weight, length of radicles and seedling, number of normal and abnormal seedlings, seed vitality, germination rate and seedling vigor index.(at the level of.0.001).and length of plumules.(at the level of.0.01)..Seedling, which was grown in standard conditions, had lower dry weight due to higher respiration and faster growth. Seed vitality, length of radicles and seedling, number of normal seedlings, germination rate and reduction of seedling weight due to daily respiration was higher in standard conditions and length of plumules, seedling vigor index and number of abnormal seedlings was greater in seeds under treatment of coldness. Second factor was influenced on some characters such as seedling dry weight, seedling vigor index (at the level of 0.001).and length of plumules and seedling, number of normal seedlings and length of radicles, number of abnormal seedlings.(at the level of 0.01),.too..OPTION500.and. RG405/02 cultivars had the greatest and KIMBERLY, HYOLA330 and AMICA cultivars had the lowest seed weight, seedling dry weight, length of radicles, total length of seedling and seedling vigor index. Also.RG405/02.and OPTION500.cultivars had the highest and. RGSOO3.and. ORS3150-3006.cultivars had the lowest final germination. Interaction effect was only significant on the length of plumules. Length of plumules of. RGSOO3.cultivar showed a significant increase in coldness treatment in comparison with standard conditions. RG405/02.seeds, in consequence of higher seed weight, could generate higher seedling dyy weight, length of radicles and seedling, missing dry matter amount during germination due to respiration and seed vitality, in both standard and coldness conditions.