상추는 전형적인 광발아 종자로서 품종별, 광질 및 생장조절물질 등의 영향을 크게 받는다. 대부분의 품종은 백색광과 적색광 하에서는 85% 이상의 발아율을 보였으나, 청색광에서는 발아세가 저하되었으며, 초적색광에서는 거의 모든 품종에서 발아가 되지 않아 광에 의한 발아억제효과가 인정되었다. 'Cheongguangcheongchima'는 초적색광 하에서도 78%, 'Okdol'은 63%, 'Manchudaecheongchima'도 48% 이상의 발아율을 나타내어 이들 품종은 광에 둔감한 품종으로 분류되었다. 초적색광의 발아 불량조건 하에서 BAP와 kinetin은 종자발아 및 정상유묘출현율을 촉진시킨 반면, ethephon은 효과적이지 못하였다. BAP, kinetin, TDZ, zeatin과 같은 cytokinin류는 50mg·L-1 이하로 처리하여 초적색광에 의한 발아억제효과가 상쇄되었으나, IBA, 2,4-D, NAA의 auxin류는 별다른 극복효과를 나타내지 않았다.
Lettuce, a typical light-induced seed germination type, exhibits different germination responses according to cultivars, light quality, and plant growth regulator (PGR) treatments. Germination rates in most tested cultivars were over 85% under both white and red light, and were slightly decreased by blue light. Although photo-inhibition in germination was observed from most cultivars by far-red light, 'Cheongguangcheongchima', 'Okdol', and 'Manchudaecheongchima' could be classified as photo-insensitive lettuce cultivars by exhibiting the germination rates as 78,63, and 48% under for-red light, respectively. 6-Benzylamino purine (BAP) and kinetin promoted seed germination and normal seedling production under far-red light, but ethephon did not show any positive effects. Cytokinins such as BAP, kinetin, thidiazuron (TDZ), and zeatin overcame photo-inhibition of seed germination even the concentration of below 50 mg·L-1. However, auxins such as IBA, 2,4-D, and NAA failed to overcome the far-red light-induced photo-inhibition.