Abstract: In order to study  the effects of different frequency duty ratio combinations on the photosynthesis of lettuce, this paper took lettuce as test material; screened 3 combined treatments (T1: 2 048 Hz+20%; T2: 512 Hz+40%; T3: 128 Hz+80%) of minimum frequency and duty cycle under the conditions of the same net photosynthetic rate with continuous light; and taking the continuous light as the control(CK) studied the effect of different pulsed light on growth, quality and photosynthetic characteristics of lettuce. The results showed that the overall effect of pulsed light supply mode on lettuce morphology, dry and fresh weights, photosynthetic parameters and chlorophyll fluorescence parameters were not significant, but the content of chlorophyll could be significantly increased by high frequency and low duty ratio pulsed light treatment(T1). Except the content of VC, the quality indexes of lettuce under pulsed light treatment were not worse than those with continuous light, and some indexes such as nitrate nitrogen, soluble total sugar and reducing sugar were even better. As a whole, the quality of lettuce under T1 was the best, indicating under the same net photosynthetic rate as same as continuous light, the feeding mode of pulsed light, would not affect the growth of lettuce, but improve the quality. Under low frequency and high duty ratio pulsed light the lettuce had a better quality, but in actual production suitable light source should be chosen combined with pulsed light energy consumption.

Key words: pulsed light, lettuce, quality, photosynthetic characteristics

摘要： 为研究不同频率占空比组合对生菜光合作用的影响，以生菜为试验材料，筛选出与连续光相同净光合速率条件下的3个最小频率与占空比的组合处理（T1：2 048 Hz+20%；T2：512 Hz+40%；T3：128 Hz+80%），并以连续光为对照（CK），研究脉冲光对生菜生长、品质及光合特性的影响。结果表明，脉冲光供光模式对生菜形态、干鲜重、光合参数、叶绿素荧光参数总体影响不大，但高频低占空比处理（T1）能显著提高叶绿素含量；除维生素C含量外，所有脉冲光处理下生菜品质指标表现均不劣于连续光（CK），硝态氮含量、可溶性总糖及还原糖含量均优于连续光，总体来说T1处理的品质最好。说明在与连续光相同的净光合速率条件下，脉冲光的供光模式不仅不影响生菜生长，还能改善品质；低频高占空比组合的脉冲光处理生菜品质更好，但在实际生产中应结合脉冲光能耗选择合适的光源。

关键词: 脉冲光, 生菜, 品质, 光合特性