Lithuanian Research Centre for Agriculture and Forestry, Institute of Horticulture, Kaunas, Lithuania.
Institute of Photonics and Nanotechnology, Vilnius University, Vilnius, Lithuania.
J Sci Food Agric. 2019 Nov;99(14):6608-6619. doi: 10.1002/jsfa.9948. Epub 2019 Sep 1.
Understanding plant responses to light quantity in indoor horticultural systems is important for optimising lettuce growth and metabolism as well as energy utilisation efficiency. Light intensity and photoperiod sufficient for normal plant growth parameters might be not efficient for nitrate assimilation. Therefore, this study explored and compared the effects of different light intensities (100-500 μmol m s ) and photoperiods (12-24 h) on the growth and nitrate assimilation in red and green leaf lettuce (Lactuca sativa L.).
For efficient nitrate assimilation, 300-400 μmol m s photosynthetic photon flux density (PPFD) and 16-18 h photoperiod is necessary for red and green lettuces. The insufficient light quantity resulted in reduced growth and remarkable increase in nitrate and nitrite contents in both cultivars. Short photoperiods, similarly to low PPFD, growth parameters, chlorophyll indices and nitrate assimilation indices showed the shortage of photosynthetic products for normal plant physiological processes. Short photoperiods had the least pronounced effect on nitrate and nitrite contents in lettuce leaves.
Light intensity was superior compared to photoperiods for efficient nitrate assimilation in both lettuce cultivars. Under short photoperiods, similarly to low intensity, growth parameters, chlorophyll index and nitrate assimilation indices showed a shortage of photosynthetic products for normal physiological processes. The free amino acid concentration increased, but it was not efficiently incorporated in proteins, as their level in lettuce was lower compared to those for moderate photoperiods. © 2019 Society of Chemical Industry.
了解室内园艺系统中植物对光量的响应对于优化生菜生长和代谢以及能源利用效率非常重要。对于硝酸盐同化来说，足以满足正常植物生长参数的光强和光周期可能效率不高。因此，本研究探索并比较了不同光强（100-500 μmol m s ）和光周期（12-24 h）对红色和绿色生菜（Lactuca sativa L.）生长和硝酸盐同化的影响。
为了有效同化硝酸盐，红色和绿色生菜需要 300-400 μmol m s 的光合光子通量密度（PPFD）和 16-18 h 的光周期。光照不足会导致生长减少，两种品种的硝酸盐和亚硝酸盐含量显著增加。与低 PPFD 类似，短光周期也会导致生长参数、叶绿素指数和硝酸盐同化指数减少，表明光合作用产物不足，无法满足正常植物生理过程的需要。短光周期对生菜叶片中硝酸盐和亚硝酸盐含量的影响最小。
与光周期相比，光强更有利于两种生菜品种的硝酸盐有效同化。在短光周期下，与低光强类似，生长参数、叶绿素指数和硝酸盐同化指数均表明光合作用产物不足，无法满足正常生理过程的需要。游离氨基酸浓度增加，但未能有效地掺入蛋白质中，因为其在生菜中的水平低于中光周期的水平。© 2019 英国化学学会。
