Effect of Treatment Light Colour (Red/Blue) and Growth Light Intensity (High/Low) as binary interaction terms on the weighted regression of Φi PSII vs 1 - qP
Where:
Treatment Light Colour = colour 
Growth Light Intensity = Growth.Light
Φi PSII = Sigma.i.PSII
1 - qP = one.minus.qp

Call:
lm(formula = Sigma.i.PSII ~ colour * Growth.Light * one.minus.qp, 
    data = colour.test, weights = 1/Sigma.i.PSII.CI)

Weighted Residuals:
       Min         1Q     Median         3Q        Max 
-1.109e-03 -2.975e-04  4.551e-05  3.784e-04  1.469e-03 

Coefficients:
                                           Estimate Std. Error t value Pr(>|t|)   
(Intercept)                               3.286e-07  1.013e-07   3.244  0.00182 **
colourBlue                                1.330e-07  1.083e-07   1.227  0.22381   
Growth.LightHigh                         -1.017e-07  1.576e-07  -0.645  0.52079   
one.minus.qp                              2.080e-07  1.458e-07   1.427  0.15809   
colourBlue:Growth.LightHigh              -7.001e-08  1.758e-07  -0.398  0.69160   
colourBlue:one.minus.qp                   1.097e-07  1.560e-07   0.703  0.48435   
Growth.LightHigh:one.minus.qp            -1.271e-07  3.080e-07  -0.413  0.68108   
colourBlue:Growth.LightHigh:one.minus.qp  3.405e-07  3.298e-07   1.032  0.30551   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.0005516 on 69 degrees of freedom
  (2 observations deleted due to missingness)
Multiple R-squared:  0.6788,	Adjusted R-squared:  0.6462 
F-statistic: 20.83 on 7 and 69 DF,  p-value: 8.995e-15

Growth Light Intensity showed no effect; collapse down to look only at Treatment Light Colour


Effect of Treatment Light Colour (Red/Blue) as a binary interaction term on the weighted regression of Φi PSII vs 1 - qP

Call:
lm(formula = Sigma.i.PSII ~ colour * one.minus.qp, data = colour.test, 
    weights = 1/Sigma.i.PSII.CI)

Weighted Residuals:
       Min         1Q     Median         3Q        Max 
-1.026e-03 -3.458e-04  3.596e-05  4.267e-04  1.521e-03 

Coefficients:
                         Estimate Std. Error t value Pr(>|t|)   
(Intercept)             2.090e-07  7.350e-08   2.844  0.00578 **
colourBlue              2.101e-07  8.138e-08   2.582  0.01184 * 
one.minus.qp            3.220e-07  1.192e-07   2.701  0.00858 **
colourBlue:one.minus.qp 4.782e-08  1.297e-07   0.369  0.71347   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.0005776 on 73 degrees of freedom
  (2 observations deleted due to missingness)
Multiple R-squared:  0.6274,	Adjusted R-squared:  0.6121 
F-statistic: 40.98 on 3 and 73 DF,  p-value: 1.23e-15