短期连续光照下水培生菜品质指标变化及其关联性分析

以温室自然光照下水培20 d的生菜为试验材料, 研究其在72 h连续光照下叶片和叶柄中硝酸盐、可溶性糖及Vc含量的变化规律及其关联性。结果表明: 在72 h的连续光照下, 生菜叶片和叶柄中的硝酸盐含量大幅度降低, 但在不同光照时期降低速度各不相同, 叶片和叶柄中的硝酸盐含量分别在连续光照24 h和48 h后趋向于稳定; 而可溶性糖和Vc含量以近似恒定的速度快速提高, 其增速在72 h后并未表现出变缓趋势。可溶性糖在叶片和叶柄中的分布无显著差异, 但叶片中的Vc含量显著高于叶柄。无论是在叶片还是叶柄中, 硝酸盐含量与可溶性糖及Vc含量均呈极显著负相关。短期连续光照可实现生菜低硝酸盐与高可溶性糖及Vc的统一, 显著提高了生菜的综合品质。

Changes in and correlation analysis of quality indices of hydroponic lettuce under short-term continuous light

Nitrate easily accumulates in vegetables (especially leaf vegetables) and poses serious health hazard if excessively ingested. Light is a critical environmental factor influencing plant nitrate content. In this study, changes in contents of nitrate, soluble sugar and vitamin C (Vc) in hydroponic lettuce under 72 h continuous light and their correlation were analyzed. The aim of the study was to explore quality control measures of vegetables grown in controlled environments. The study showed that nitrate content in both leaf blade and petiole decreased significantly with variational rate in different time. Nitrate content in blade and petiole tended to steady after 24 h and 48 h continuous light respectively, while soluble sugar and Vc contents increased rapidly at a roughly constant rate and showed little trend of slowing down. There was no significant difference between blade and petiole soluble sugar contents. However, blade Vc content was much higher than that in petiole. Both in blade and petiole, nitrate content was significantly negatively correlated with soluble sugar and Vc contents. The results showed that short-term exposing to continuous illumination was suited to produce high quality lettuce with perfect unity of low nitrate accumulation and high soluble sugar and Vc contents.