Effects of light colors on plants especially on effects of blue and twilight on Fuchsia and Hibiscus

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1 Effects of light colors on plants especially on effects of blue and twilight on Fuchsia and Hibiscus Greentech, RAI Amsterdam 15 June 2016, Filip van Noort

2 Photosynthesis at different light colors PAR light: nm Energy content photon determines efficiency of photosynthesis Highest efficiency photon: around 640 nm (red) 2

3 Light two functions Growth by supplementary light PAR light ( nm) Light intensity x duration = daily light integral Quality (plant shape, flowering): steering light UV, purple, blue ( nm) Red ( nm) Far Red ( nm) 3

4 How do plants respond to light? Through photoreceptors: phytochromes: R/FR ratio Cryptochromes: daylength Phototropins: movement towards light, stomata opening Influence on hormonal balance (auxins, gibberellins, cytokinins) and therefore on stomata opening, elongation, flowering, secondary metabolites 4

5 Supplementary light HPS Plasma lamps LED Differences in spectrum: HPS: much yellow/red Plasma: approaches sunlight LED: peaks in desired light color 5

6 Effects light color on tomato Young plants 3 weeks, 6 different light colors (200 μmol/m 2 /s): White Red Blue Amber Green Red/blue

7 Effects of light colors on tomato

8 Blue light Compact growth Small, thick leaves Higher pigment content Stomata wider open Stomata opening(h 2 O/m 2 /s) Tomato 8

9 Far-red light ( nm) Shade avoiding syndrom Stimulates elongation (petioles, internodes) Inhibits branching Bigger surface, thinner leaves Promotes flowering (?!) Promotes rooting 9

10 Red light Promotes photosynthesis Stimulates branching and compact plants Effects through red/far-red ratio Plays a role in plant resistance 10

11 Green light Higher reflection and transmission Gives elongation and open plant structure Opposite of blue light Effects are comparable to the effects of FR 11

12 Trial Fuchsia and Hibiscus Trial with different amounts of blue light in combination with or without twilight because To prevent elongation in some crops To investigate if blue could be an alternative for growth retardants The trial is financed from the strategic resources of the Club 100 of Wageningen UR Greenhouse Horticulture and the Top sector Horticulture and Propagation Materials 12

13 Design Trial with Hibiscus rosa-sinensis (4 varities) and Fuchsia (1 variety): Amounts of blue light (LED): 10%, 30% and 50% blue light Contribution of blue light from the sun is included 100 μmol/m 2 /s lamps; target 30 μmol/m 2 /s from outside (heavy screening) Different R/FR ratio s at the end of the day natural R/FR ratio in twilight Use artificial red light during twilight (high R/FR ratio)

14 high blue

15 Fuchsia (wk wk ) From left to right: 30% blue, 10% blue, 50% blue without twilight; 50% blue, 30% blue and 10 blue with twilight Left (3): more compact plants 50% blue are most compact plants (2 plants in the middle) 15

16 Hibiscus (wk wk ) From left to right: 10% blue, 30% blue, 50% blue without twilight; 10% blue, 30% blue and 50 blue with twilight No relevant differences 16

17 Conclusions Blue light give opportunities to replace growth retardants (partially) In some species If weight reduction is not a problem for quality Avoiding higher FR at the end of day trough screening and giving more red (and blue) is also reducing elongation and with fuchsia earlier flowering Combination of both actions have effect on more compact growth (In september almost the same trial will start again) 17

18 Thank you for your attention Special thanks to collegaes Tom Dueck, Anja Dieleman Thanks to: Ministry of economic affairs LTO Glaskracht EU Climate-KIC 18

19 Resultaten tussenmeting Tussenmeting Fuchsia: 18 januari 2016 Invloed schemering tafel Natuurl. schemer Bloei stadium* Lengte (cm) Aantal interno. Versgew. blad Versgew. stengel bladopp. 10 bladeren** 9-11 ja nee Lsd95% n.s Gemiddelde van 30 meetplanten * 5 ontwikkelingsstadia van geen bloem tot gekleurde open bloem **2e internodie na vertakking

20 Resultaten tussenmeting Tussenmeting Fuchsia: 18 januari 2016 Invloed lichtkleur blauw (%) Nat. schemer bloei stadium* lengte (cm) aantal interno. Versgew. blad Versgew. stengel bladopp. 10 bladeren** 10 ja d c 26.8 d ja c c 22.9 c ja c c 22.4 c nee b a 17.8 b nee c b 22.9 c nee a a 16.2 a 129 Lsd95% n.s. 2.5 n.s n.s. * 5 ontwikkelingsstadia van geen bloem tot gekleurde open bloem **2e internodie na vertakking

21 Resultaten eindmeting Eindmeting Fuchsia (7 maart) na toppen in jan. Invloed schemering tafel Natuurl. schemer Bloei stadium* Lengte (cm) Aantal internod. Versgew. Blad Versgew. stengel bladopp. 10 bladeren 9-11 ja nee Lsd95% n.s. Gemiddelde van 30 meetplanten * 5 ontwikkelingsstadia van geen bloem tot gekleurde open bloem

22 Resultaten eindmeting Eindmeting Fuchsia (7 maart) na toppen in jan. Invloed lichtkleur blauw (%) Schemer/ge en schemer bloei stadium lengte (cm) aantal interno. Versgew. blad Versgew. stengel bladopp. 10 bladeren** 10 samen b 8.2 b b samen ab 7.3 a a samen a 8.0 b ab 89 Lsd95% n.s n.s. 3.8 n.s. Gemiddelde van 20 meetplanten per behandeling