INTERNATIONAL JOURNAL OF AGRICULTURAL TECHNOLOGY

Volume 15, No. 01, Month JANUARY, Year 2019, Pages 75 - 90

Effects of light intensity on the growth, photosynthesis and leaf microstructure of hydroponic cultivated spinach (spinacia oleracea l.) under a combination of red and blue leds in house

Nguyen, T. P. D., Tran, T. T. H. and Nguyen, Q. T.

Abstract Download PDF

The effect of four different light intensities (90, 140, 190 and 240 μmol/m2/s) on the growth, photosynthesis and leaf microstructure of hydroponic cultivated spinach under a combination of red and blue LEDs (R660/B450 = 80/20) in house was investigated. The plant height, leaf number, leaf area, NGR, NAR, Chla, Chl(a +b), photosynthetic capacity increased with increasing intensity. Althrough, there was not statistically significant difference in Chl(a+b) and carotenoid contents between the 190 and 240 μmol/m2/s treatments but they differed in Chla. Furthermore, the leaf area, NGR, NAR, Chla and Chl(a+b) contents were significantly higher in 190 μmol/m2/s treatment than 240 μmol/m2/s treatment. Differences in leaf thickness, palisade tissue length and spongy tissue length were statistically significant between 4 treatments. Even, leaf thickness in 190 μmol/m2/s treatment was found by 1.4 folds increased compare with 90 μmol/m2/s treatment. When light intensity increased, epidermal cell area, stomatal length, stomatal width increased. In the adaxial leaf surface and abaxial leaf surface, the epidermal cell area was highest in 190 μmol/m2/s treatment. But in all two leaf surfaces stomatal width was highest in the 240 μmol/m2/s treatment. The results showed that fresh weight and dry weight of stem and leaf, theoretical yeild, final harvest yeild were not highest in 240 μmol/m2/s treatment but in 190 μmol/m2/s treatment. Our results suggested that 190 μmol/m2/s light intensity may be appropriated the intensity for growth of spinach.

Keywords

carotenoid, Fv/Fm, leaf thickness, stomatal length, palisade tissue length

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