>20% Light Use Efficiency Exhibited in Tomato Trial

Results 

The objectives of this study are to evaluate the effects of an altered sunlight environment resulting from the application of a retrofit QD film on the growth and fruit production of greenhouse-grown tomato plants. The hypothesis is that a red-shifted spectrum and increased light diffusion compared to a control greenhouse compartment will overcome a reduction in light intensity to result in higher fruit production and increased vegetative growth metrics.

Throughout the experiment, vegetative growth metrics were monitored by selecting two rows with eight tomato stems in each compartment and the following parameters were measured weekly: vine length, head thickness, number of set trusses, number of flowering trusses, number of fruits set, leaf length, number of leaves, flowering speed, and ripening time. On average, plants under the QD film grew 2.1 cm/week faster than control plants, corresponding to a +9.7% increase in vine growth. The average weekly leaf length showed a 3.8-cm increase under the QD film, a +9.5% increase. Other growth metrics showed negligible differences between the plants grown in the test and control compartments. A t-test on two samples assuming unequal variances was performed on vegetative growth metrics using each measurement week for n = 23, resulting in a p-values (two tails). p-values < 0.05 indicate that the difference in the measured metric was significant over the variance in the dataset. The data show statistical significance for both vine growth and leaf length, but no statistical significance for the other metrics, although production of one additional leaf per plant on average, over the duration of the trial, was relatively close to significant. While internodal spacing was not measured in this study, the observed increase in leaf number, leaf length, and vine length indicates more vigorous growth under the QD film. Flowering speed and fruit set data for the trial can be found in the supplemental information within the trial document.

Despite a 14% reduction in overall DLI under the QD film, this altered spectral and diffuse light environment employed over tomato plants gave rise to a +10% faster vegetative growth rate (vine stem and leaf length) and -36% reduced fruit waste, resulting in an overall +5.7% improved saleable production yield per unit area. With a +4.4% increase in Far-Red light content under the QD film, the increase in vine stem elongation and leaf length are not surprising, especially when accompanied by a reduced DLI.