Layering contrasting photoselective filters improves the simulation of foliar shade

Table 9 The effects of high-pressure sodium (HPS) lamps on filter spectral quality

Filter(s)	R:FR^a	PPE^b	B:G^c	Blue^d	Green^e	Red^f	PPF reduction^g
Filter(s)	R:FR^a	PPE^b	B:G^c	%
Lamp only	3.45 Aⁱ	0.87 A	0.23 C	6.0 C	59.3 G	34.7 A	–
0.60 ND^h	0.73 D	0.80 C	0.20 D	5.4 D	64.6 D	30.0 C	79.0 D
1/2 CTB	1.25 C	0.84 B	0.40 A	10.0 A	60.0 F	30.0 C	53.0 E
1/2 PG	2.47 B	0.87 A	0.14 E	5.1 D	62.6 E	32.3 B	22.3 F
0.60 ND + 1/2 CTB	0.28 F	0.73 E	0.29 B	7.4 B	66.6 C	26.0 E	90.3 B
0.60 ND + 1/2 PG	0.54 E	0.79 D	0.11 F	4.0 E	68.0 B	28.0 D	83.3 C
0.60 ND + 1/2 PG + 1/2 CTB	0.21 F	0.70 F	0.15 E	6.0 C	69.5 A	24.5 F	92.3 A

^aR:FR = 655–665/725–735
^bPPE = Phytochrome photoequilibria
^cB:G = 420–490/500–570
^dBlue = Percentage of PPF between 400 and 499 nm relative to total PPF
^eGreen = Percentage of PPF between 500 and 599 nm relative to total PPF
^fRed = Percentage of PPF between 600 and 700 nm relative to total PPF
^gPPF reduction = Percent reduction in PPF relative to full sun; PPF from HPS lamps only = 41 µmol m⁻² s⁻¹
^hRosco Cinegel was used for CTB and Rosco e-colour + was used for PG and ND filters
ⁱData are presented as averages acquired on three different days: 12 June, 13 June, and 14 June 2020 at 22:00 h in a greenhouse. Means are only compared within column and were separated with Fisher’s LSD. Means followed by a common letter are not significantly different (P = 0.05)

ISSN: 1746-4811