The results of the floral color (Table I) and their respective difference over period of time are shown in Table II. Figure 1a to 1f depicts the flowers selected for the study.
Floral color difference calculated as delta E 2000 between species studied. Delta E 2000 > 3.5 between two consecutive measurements (highlighted as bold digits) indicates perceptible difference in flower colour (Table II). Petal color of Allamanda cathartica did not have any perceptible difference during the time period of observation. Although color of Hibiscus rosasinensis was more or less constant, a discernible difference was found for consecutive measurements made at 14.30 PM and 15.15 PM. Wrightia tinctoria, recorded constant color for the first couple of hours of the day and then showed consistent changes till 1.00 PM.
Table I. Floral color change over period of time (9.00 AM to 4.00 PM)
Species | Lab | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 | T12 | T13 |
Allamanda cathartica | L | 28.79 | 28.87 | 28.11 | 28.60 | 27.56 | 27.71 | 28.17 | 27.51 | 27.37 | 27.08 | 27.36 | 27.41 | 27.19 |
a | 15.93 | 12.49 | 10.19 | 14.46 | 13.17 | 13.27 | 14.03 | 13.76 | 16.05 | 17.44 | 17.19 | 17.46 | 16.68 |
b | 34.36 | 32.87 | 32.62 | 34.17 | 34.38 | 34.27 | 34.16 | 33.86 | 34.50 | 34.92 | 34.81 | 35.06 | 34.66 |
Hibiscus rosasinensis | L | 26.43 | 26.86 | 26.46 | 26.04 | 26.38 | 26.60 | 26.31 | 26.05 | 25.96 | 26.43 | 26.24 | 28.41 | 27.41 |
a | 34.75 | 37.29 | 31.30 | 32.03 | 34.51 | 33.68 | 33.18 | 27.29 | 25.23 | 31.63 | 28.98 | 39.91 | 36.43 |
b | 16.78 | 18.42 | 16.90 | 15.39 | 17.38 | 19.45 | 17.13 | 13.44 | 15.18 | 18.47 | 17.78 | 24.86 | 21.29 |
Wrightia tinctoria | L | 27.48 | 27.01 | 27.43 | 27.38 | 27.17 | 27.44 | 27.27 | 27.27 | 27.37 | 27.26 | 27.12 | 27.40 | 27.86 |
a | 0.31 | 0.98 | -2.27 | -1.14 | 1.56 | -4.08 | -0.92 | 0.88 | -0.98 | 0.53 | 0.85 | -0.90 | -6.81 |
b | 8.86 | 9.01 | 9.51 | 9.46 | 7.32 | 8.37 | 8.28 | 13.67 | 8.24 | 11.46 | 10.51 | 8.07 | 9.93 |
Portulaca grandifolia | L | 26.74 | 26.32 | 26.36 | 26.24 | 26.52 | | | | | | | | |
a | 29.65 | 19.66 | 15.61 | 17.66 | 21.08 | | | | | | | | |
b | 35.06 | 30.80 | 20.00 | 28.78 | 31.50 | | | | | | | | |
Melastoma malabathricum | L | 27.90 | 27.07 | 25.67 | 27.99 | 28.66 | 26.30 | 27.37 | | | | | | |
a | 41.18 | 37.57 | 31.24 | 40.70 | 43.76 | 29.58 | 35.42 | | | | | | |
b | 1.12 | -0.74 | -8.03 | 1.54 | 2.10 | 2.41 | 6.71 | | | | | | |
Hibiscus mutabilis | L | 28.30 | 28.20 | 28.47 | 28.53 | 28.35 | 28.32 | 27.09 | 26.63 | 26.67 | 28.19 | 29.87 | 30.15 | 31.33 |
a | 1.75 | 1.15 | -1.98 | -2.88 | -1.44 | -3.03 | 10.23 | 21.62 | 27.56 | 38.36 | 45.07 | 45.63 | 49.11 |
b | 22.97 | 19.10 | 15.88 | 14.57 | 14.92 | 10.15 | 14.56 | 14.09 | 13.57 | 20.20 | 25.03 | 27.71 | 30.17 |
* L – Lightness, a –Red/ Green, b – Yellow/ Blue
* T1 (9.00AM), T2 (9.30AM), T3(10.00AM), T4(10.30AM), T5(11.00AM), T6(11.30AM), T7(12.00PM), T8(12.30PM), T9 (1.00 PM), T10(1.45PM), T11(2.30PM), T12(3.15PM), T13(4.00PM).
Table II. Floral color difference in selected species between 9.00AM to 4.00PM
Time | Species | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 | T12 | T13 |
T1 | a | 0.00 | | | | | | | | | | | | |
b | 0.00 | | | | | | | | | | | | |
c | 0.00 | | | | | | | | | | | | |
d | 0.00 | | | | | | | | | | | | |
e | 0.00 | | | | | | | | | | | | |
f | 0.00 | | | | | | | | | | | | |
T2 | a | 2.24 | 0.00 | | | | | | | | | | | |
b | 1.14 | 0.00 | | | | | | | | | | | |
c | 0.99 | 0.00 | | | | | | | | | | | |
d | 5.15 | 0.00 | | | | | | | | | | | |
e | 1.78 | 0.00 | | | | | | | | | | | |
f | 2.04 | 0.00 | | | | | | | | | | | |
T3 | a | 3.94 | 1.78 | 0.00 | | | | | | | | | | |
b | 1.62 | 2.42 | 0.00 | | | | | | | | | | |
c | 3.46 | 4.40 | 0.00 | | | | | | | | | | |
d | 7.99 | 5.17 | 0.00 | | | | | | | | | | |
e | 6.82 | 5.15 | 0.00 | | | | | | | | | | |
f | 5.63 | 4.12 | 0.00 | | | | | | | | | | |
T4 | a | 1.01 | 1.29 | 2.94 | 0.00 | | | | | | | | | |
b | 1.19 | 2.32 | 1.20 | 0.00 | | | | | | | | | |
c | 2.01 | 2.92 | 1.48 | 0.00 | | | | | | | | | |
d | 6.17 | 1.18 | 4.43 | 0.00 | | | | | | | | | |
e | 0.30 | 1.84 | 6.93 | 0.00 | | | | | | | | | |
f | 7.05 | 5.54 | 1.43 | 0.00 | | | | | | | | | |
T5 | a | 2.19 | 1.18 | 2.06 | 1.26 | 0.00 | | | | | | | | |
b | 0.43 | 1.13 | 1.37 | 1.30 | 0.00 | | | | | | | | |
c | 2.16 | 1.56 | 5.46 | 4.10 | 0.00 | | | | | | | | |
d | 4.36 | 0.80 | 5.46 | 1.93 | 0.00 | | | | | | | | |
e | 1.17 | 2.94 | 7.87 | 1.20 | 0.00 | | | | | | | | |
f | 5.63 | 3.90 | 0.82 | 1.78 | 0.00 | | | | | | | | |
T6 | a | 2.05 | 1.08 | 2.11 | 1.11 | 0.15 | 0.00 | | | | | | | |
b | 1.93 | 2.00 | 1.44 | 2.30 | 1.50 | 0.00 | | | | | | | |
c | 5.79 | 6.75 | 2.51 | 3.90 | 7.57 | 0.00 | | | | | | | |
e | 4.77 | 3.81 | 6.24 | 4.60 | 5.69 | 0.00 | | | | | | | |
f | 9.53 | 7.73 | 4.09 | 2.94 | 3.91 | 0.00 | | | | | | | |
T7 | a | 1.39 | 1.13 | 2.62 | 0.45 | 0.82 | 0.67 | 0.00 | | | | | | |
b | 0.83 | 1.66 | 0.83 | 1.00 | 0.55 | 1.36 | 0.00 | | | | | | |
c | 1.76 | 2.67 | 1.90 | 0.90 | 3.54 | 4.00 | 0.00 | | | | | | |
e | 4.08 | 4.52 | 8.91 | 3.80 | 4.36 | 3.46 | 0.00 | | | | | | |
f | 11.33 | 11.05 | 14.32 | 15.44 | 13.62 | 15.94 | 0.00 | | | | | | |
T8 | a | 1.74 | 1.32 | 2.51 | 0.94 | 0.58 | 0.49 | 0.53 | 0.00 | | | | | |
b | 3.25 | 4.33 | 2.28 | 2.10 | 3.26 | 3.70 | 2.80 | 0.00 | | | | | |
c | 3.25 | 3.12 | 5.07 | 3.90 | 4.54 | 7.60 | 4.35 | 0.00 | | | | | |
f | 19.57 | 19.46 | 22.68 | 23.76 | 21.99 | 24.11 | 8.72 | 0.00 | | | | | |
T9 | a | 1.08 | 2.57 | 4.01 | 1.41 | 2.04 | 1.95 | 1.49 | 1.51 | 0.00 | | | | |
b | 4.28 | 5.17 | 2.77 | 3.30 | 4.10 | 3.80 | 3.56 | 1.89 | 0.00 | | | | |
c | 1.84 | 2.77 | 1.83 | 0.90 | 3.62 | 3.90 | 0.12 | 4.42 | 0.00 | | | | |
f | 22.74 | 22.47 | 25.44 | 26.44 | 24.76 | 26.70 | 11.96 | 3.41 | 0.00 | | | | |
T10 | a | 1.60 | 3.45 | 4.91 | 2.25 | 2.93 | 2.85 | 2.39 | 2.41 | 0.91 | 0.00 | | | |
b | 2.15 | 2.60 | 0.92 | 2.10 | 1.76 | 0.86 | 1.35 | 3.00 | 2.96 | 0.00 | | | |
c | 1.81 | 1.84 | 4.02 | 2.70 | 3.36 | 6.60 | 2.98 | 1.46 | 3.10 | 0.00 | | | |
f | 25.19 | 24.79 | 27.46 | 28.33 | 26.75 | 28.33 | 14.98 | 7.37 | 4.94 | 0.00 | | | |
T11 | a | 1.34 | 3.23 | 4.73 | 2.02 | 2.76 | 2.68 | 2.18 | 2.24 | 0.73 | 0.26 | 0.00 | | |
b | 3.07 | 3.71 | 1.49 | 2.60 | 2.75 | 2.00 | 2.24 | 2.57 | 1.92 | 1.20 | 0.00 | | |
c | 1.36 | 1.08 | 4.27 | 2.80 | 2.59 | 6.80 | 2.88 | 2.05 | 2.98 | 0.80 | 0.00 | | |
f | 26.73 | 26.31 | 28.91 | 29.72 | 28.17 | 29.50 | 16.83 | 9.91 | 7.82 | 2.99 | 0.00 | | |
T12 | a | 1.40 | 3.36 | 4.87 | 2.13 | 2.89 | 2.81 | 2.31 | 2.38 | 0.87 | 0.25 | 0.16 | 0.00 | |
b | 4.40 | 3.54 | 4.59 | 5.30 | 4.11 | 3.23 | 4.31 | 6.81 | 6.70 | 4.00 | 4.90 | 0.00 | |
c | 1.77 | 2.69 | 1.98 | 1.00 | 3.49 | 4.00 | 0.18 | 4.46 | 0.16 | 3.10 | 2.96 | 0.00 | |
f | 26.39 | 26.06 | 28.73 | 29.57 | 28.00 | 29.42 | 16.81 | 10.33 | 8.60 | 3.95 | 1.37 | 0.00 | |
T13 | a | 1.30 | 2.99 | 4.43 | 1.81 | 2.45 | 2.37 | 1.92 | 1.93 | 0.43 | 0.48 | 0.35 | 0.50 | 0.00 |
b | 2.57 | 1.98 | 2.66 | 3.40 | 2.23 | 1.32 | 2.37 | 4.92 | 5.00 | 2.10 | 3.20 | 1.95 | 0.00 |
c | 8.65 | 9.64 | 5.16 | 6.60 | 10.60 | 2.97 | 6.91 | 9.95 | 6.80 | 9.20 | 9.51 | 6.90 | 0.00 |
f | 27.30 | 26.97 | 29.62 | 30.45 | 28.89 | 30.23 | 17.87 | 11.67 | 10.02 | 5.39 | 2.54 | 1.53 | 0.00 |
* T1 (9.00AM), T2 (9.30AM), T3(10.00AM), T4(10.30AM), T5(11.00AM), T6(11.30AM), T7(12.00PM), T8(12.30PM), T9 (1.00 PM), T10(1.45PM), T11(2.30PM), T12(3.15PM), T13(4.00PM).
* Species a, b, c, d, e and f representes Allamanda cathartica, Hibiscus rosasinensis, Wrightia tinctoria, Portulaca grandifolia, Melastoma malabathricum and Hibisus mutabilis respectively.
Perceptible difference in color was observed in 3 out of 4 consecutive measurements on flowers of Portulaca grandifloria, carried out at 30 minutes interval. The flower has a very short life span. Three instances of perceptible difference in color were observed in flowers of Melastoma malabathricum during the day. Flower colour of Hibiscus mutabilis was discernibly different during almost 40% of the 13 recordings. The transition was more during mid to late hours. The highest magnitude (15.94) of Delta E 2000 was recorded between 11.30AM and 12.00 PM for Hibiscus mutabilis.
The CIE L*a*b* colour space objectively represents fast colours. It is the widely adopted standard to represent colour. However, flower and floral colours are different. From a biological perspective, flower initiation is a change-over from indeterminate to determinate form of growth (Kwiatkowska 2008). Flowering is an energy intensive (Primack 2003) process and longevity of flowers range from hours to days (Ashman and Schoen 1994). Unlike fast colours that resist fading, flower colour changes with time. Spectacular floral chromatic transition is found in Hibiscus mutabilis. Petals of Hibiscus mutabilis, which are creamy white at dawn, changes to pink by afternoon and the flower withers at dusk. Highlighted cells in Table II indicates floral colour changes that are obviously different (Delta E > 3.5) (Mokrzycki and Tatol 2011). The decreasing order of color constancy observed by us was Allamanda cathartica, Hibiscus rosasinensis, Portulaca grandifolia and Melastoma malabathricum. Hibiscus mutabilis stands out as an exception.