Lettuce seedlings quality : the effects of white and blue light exposure

Abstract

In the Balkans, the production of globally cultivated green leaf lettuce (Lactuca sativa L.) can be slow due to reduced quality and intensity of solar insolation. Our research aimed to investigate the effects of artificial illumination and the duration of light exposure on the growth and quality of two lettuce genotypes seedlings: Genesis and Jukebox. The research was conducted at the Institute for Vegetable Crops Smederevska Palanka, Serbia. Lettuce seeds were sown in 9 styrofoam containers per genotype, filled with commercial substrate. In the phase of three leaves, plants were placed in plant growth chambers under multispectral white (W) LEDs and monochromatic blue (B) LEDs (three containers per LED and genotype), while three containers were kept in the greenhouse and served as control. The plants were cultured in plant growth chambers for 25 days under a 9h/15h and 10h/14h (light/dark) photoperiod, to simulate outdoor conditions. Morphological growth parameters (number of leaves and plant weight) were measured on the 11th and 25th days. Chlorophyll content was measured on the 4th, 11th, 18th and 25th days. Plants grown under W and B LEDs had a significantly higher number of leaves, plant weight, and chlorophyll content than plants grown in a greenhouse. Using energy-efficient white and blue LED lights in lettuce seedling production during 18-25 days positively impacts seedling quality, and with this seedling production, the plants can achieve high yields and quality.

Proizvodnja zelene salate (Lactuca sativa L.) na Balkanu može biti spora usled smanjenog kvaliteta i intenziteta sunčeve insolacije. Cilj ovog istraživanja bio je da se ispita uticaj veštačkog osvetljenja i trajanja izlaganja svetlosnim tretmanima na rast i kvalitet sadnica dva genotipa zelene salate: Genesis i Jukebox. Istraživanje je sprovedeno u Institutu za povrtarstvo Smederevska Palanka, Srbija. Zelena salata je zasejana u 9 kontejnera po genotipu, ispunjenih komercijalnim supstratom. U fazi tri lista, biljke su prebačene u komore za rast biljaka i gajene pod multispektralnim belim (W) i monohromatskim plavim (B) LED svetiljkama (tri kontejnera po LED svetlu i po genotipu), dok su tri kontejnera sa biljkama ostavljena u stakleniku i služila su kao kontrola. Biljke su gajene u komorama za rast biljaka 25 dana, sa 9h/15h i 10h/14h (svetlost/mrak) fotoperiodom, čime su simulirani spoljašnji uslovi. Morfološki parametri rasta (broj listova i težina biljaka) mereni su 11. i 25. dana. Sadržaj hlorofila meren je 4., 11., 18. i 25. dana. Biljke gajene pod belim i plavim LED svetiljkama imale su značajno veći broj listova, težinu i sadržaj hlorofila u poređenju sa biljkama gajenim u stakleniku. Upotreba energetski efikasnih belih i plavih LED svetiljki u proizvodnji rasada zelene salate tokom 18-25 dana pozitivno utiče na kvalitet rasada, a biljke dobijene iz ovakvog rasada mogu da ostvare visoke prinose i kvalitet.