洋葱种子含水量与贮藏温度对其寿命的影响

The Effect of Moisture Content and Storage Temperature on Onion Seed Longevity

不同含水量 (MC 7.1%～ 1.2 % )的洋葱种子贮藏在 3 5℃、室温、15℃和 5℃条件下 1～ 3年 ,适度超干处理能延长种子的贮藏寿命 ;种子的贮藏寿命与种子含水量和贮藏温度密切相关。种子贮藏的最适含水量随温度的改变而发生相应的变化 ,3 5℃时MC为3 .4 % ;室温时为 3 .4 %～ 4 .5 % ;15℃时为 4 .5 %～5 .1%。MC≤ 2 .2 %不利于延长种子寿命。在室温自然条件下贮藏 1～ 3年 ,适度超干种子 (MC 3 .4 % )内MDA和H2 O2 含量、O- ·2 产生速率和LOX活性明显地低于未超干种子 (MC 7.1% )和高度超干种子 (MC1.2 % ) ,而抗氧化酶AsA POD、CAT和SOD的活性显著地高于未超干种子 (MC 7.1% )和高度超干种子 (MC 1.2 % )。据此认为对脂质过氧化的抑制作用是适度超干种子耐贮藏的生理原因之一。

Seeds dried to moisture contents of 7.1% to 1.2% were stored at 35℃,room temperature, 15℃ and 5℃ for 1～3 years. Moderate drying during storage could improve the longevity of onion seeds, but drying to extremely low moisture contents resulted in reduced seed longevity. The optimum moisture content for onion seeds during storage depended on temperature. The optimum moisture content in which onion seeds were stored at 35℃,room temperature, 15℃ and 5℃ were 3.4%, 3.4 %～4.5%, 4.5%～5.1%, respectively (Fig.1). Excessive drying (MC≤2.2%)decreased seed longevity(Fig.1). During room temperature storage, the MDA and H 2 O 2 contents, the production rate of O -· 2and LOX activity in moderately dried seeds (MC 3.4%) were lower than those in the control (MC 7.1%) and excessively dried seeds (MC 1.2%). Activities of catalase, ascorbate peroxidase and superoxide dismutase in moderately dried seeds (MC 3.4%) were higher than those in the control (MC 7.1%) and excessively dried seeds (MC 1.2%)(Figs.2,3). These results show that aging results in a general deterioration of seed cells or organization, and that these changes can be slowed by drying seeds to moisture contents as low as 3.4%.