Vertical lamellae highly diffusive for light : Effect on growth of young tomato plants in a climate chamber

Summary

Experiments done in the past have shown a clear advantage for many crops of receiving more diffuse light in relation to direct light. However, in these experiments, extremely high light scattering levels were never tested, and therefore, we do not know whether such results could be extrapolated, and how. The scattering is quantifi ed by means of the Hortiscatter (0-100%) parameter as defi ned in norm NEN2675. In this trial an innovative material in the form of rectangular lamellae has been used, that when positioned vertically above the crop and below the source of light, can generate a very high Hortiscatter (>90%). These highly diffusive vertical lamellae were tested in three trials in a climate chamber using young tomato plants, with both direct light and a conventional Hortiscatter (50%) as reference treatments. Light interception, leaf photosynthetic capacity of different layers and dry matter (and other related production values) were compared. Despite the efforts in optimizing the set up, it was not possible to maintain a homogeneous horizontal PAR intensity distribution. However, results indicate that, regardless of the light intensity, young tomato plants under a very high Hortiscatter intercepted more PAR light in the three trials. On the other hand, both top and bottom leaves under this treatment did not show a higher photosynthetic capacity than under a direct light treatment. Finally, results indicate a trend to higher total dry matter production under the very high Hortiscatter. However, more research, if possible under sunlight conditions and trying to minimize the sources of variation are needed in the future.