The Effect of Different LED Light Qualities and Intensities on Pepper Seedling Growth

CUI Dandan; ZHANG Yuyang; DONG Yao; XIAO Tieqi; QIN Jian; HU Yue

doi:10.3969∕j.issn.1004-440X.2025.03.001

Abstract：To explore an efficient light environment for pepper seedling cultivation,this experiment was conducted in a fully artificial light seedling factory,where different light spectra and intensities were applied for the cultivation of Zhang ShuGang pepper seedlings.The growth of pepper seedlings under various light environments was compared.The experiment included four light qualities:S1(R:G:B=38％:46％:16％);S2(R:G:B:Fr(far red)=60％:18％:8％:14％);S3(R:G:B=64％:26％:10％);and S4(R:B:Fr=64％:27％:9％).Three light intensities were used:HL(235 μmol/m2·s-1),ML(160 μmol/m2·s-1),LL(95 μmol/m2·s-1),with the Daily Light Integral(DLI)of 13.5 μmol/m2·d-1,9.3 μmol/m2·d-1,and 5.5 μmol/m2·d-1,respectively.The pepper seedling experiment was carried out under 12 different treatments,and the effects of different treatments on seedling SPAD value,plant height,stem diameter and seedling vigor index were compared.The results showed that:(1)The stems of pepper seedlings became thinner with as light intensity decreased,while plant height increased as light intensity decreased.Except for the S1 light quality,the seedling vigor index of pepper seedlings was positively correlated with light intensity.Except for the S4 light quality,under moderate light intensity(160 μmol/m2·s-1),the chlorophyll content of the pepper leaves was the highest.(2)Under a similar red-to-blue light ratio,adding far-red light in the S2 light quality significantly increased the plant height of the pepper seedlings compared to other spectra,but the stems were weak.The S4 light quality,with a higher proportion of blue light,resulted in the shortest plants,with darker leaves and a higher relative chlorophyll content.Under HL treatment,the dry matter weight of pepper seedlings with the S2 light quality was significantly higher than that of the other treatments,but this phenomenon was not observed under ML and LL light intensities.