温度对叶用莴苣春化的影响

为了探讨温度对叶用莴苣春化的影响,进而明确其春化类型,本试验选用两个易抽薹叶用莴苣品种GB-30和GB-31为试材,分别进行20 d的4、20和25 ℃处理,然后均进行高温胁迫促进抽薹,采用石蜡切片观察茎尖花芽分化进程,并结合后期抽薹开花情况来判断是否进行春化,并确定其春化类型.结果表明:两个品种在前期经过3种温度处理后,在高温胁迫第8天时均有不同程度的抽薹.两个品种不同温度处理下花芽均进行了分化,前期4 ℃处理并没有使其花芽分化明显提前,后期的高温胁迫可以明显促进花芽分化进程.两品种间在不同温度处理下完成各发育阶段所需天数存在差异,两品种各处理从催芽到开花以及从高温到开花的有效积温也存在差异.前期未经低温处理的叶用莴苣也进入花芽分化、抽薹、现蕾及开花阶段,表明叶用莴苣为非低温春化型植物,后期高温处理能明显促进其抽薹开花,而且从催芽开始只有有效积温达到约2500 ℃·d才能开花.

Effects of temperature on leaf lettuce vernalization.

To investigate the effects of different temperatures on the vernalization of leaf lettuce, and declare their type, two easy bolting leaf lettuce varieties of GB-30 and GB-31 were selected as material, which were treated by 4 ℃, 20 ℃ and 25 ℃ for 20 d respectively and afterwards treated by high temperature stress. The process of flower bud differentiation was observed by using paraffin section technology, and combined the condition of bolting and flowering to estimate whether or not it underwent vernalization, and defined its vernalization type. The results showed that, two varieties of GB-30 and GB-31 appeared bolting to different degrees at the 8^th day under high temperature stress after temperature treatments in the early stage. Different temperatures in the early stage all made flower bud differentiated of two varieties. 4 ℃ treatment did not advance the flower bud differentiation, while the high temperature in later time accelerated this progress. Furthermore, the days required for the two varieties to complete development stages differed under different temperature treatments. The effective accumulated temperature whether from pregermination to flowering or from high temperature stress to flowering of two varieties were also different. The leaf lettuce without low temperature treatment in early stage could enter into the flower bud differentiation, bolting, budding and flowering stages, and it could be considered as non-low temperature vernalization plant. The high temperature treatment in later stage could obviously promote its bolting and flowering. In addition, the effective accumulated temperature had to reach about 2500 ℃·d from germination to blossom.