Additional leaf picking from the head of the crop increases production and lowers evaporation from the crop. However, leaf picking should be stopped in time. This follows from practical research by Proeftuin Zwaagdijk in crop season 2014-2015.
The study was conducted at two companies with varieties Merlice and Brioso. Both crops were illuminated in accordance with the standard tomato lighting strategy. The aim was to determine the effect of a lower Leaf Area Index (LAI) in crop development, production and energy saving. The LAI reduction was achieved by removing one additional leaf from the upper part of the plant throughout the winter period.
Up to 1 kg increase in production
With the Merlice breed this resulted in a maximum production increase of 1kg/m2 during the winter period in comparison with the standard crop. This measure also reduces the total vaporization of a crop and consequently the energy consumption. The additional leaf picking should be stopped in time because the crop’s LAI should be high enough to use all available light. An LAI that is too low in relation to the available light resulted in stress for the plants in this trial and an immediate reduction in production.
Neither in Merlice or Brioso effects were observed of the extra leaf picking in setting speed, plant load and the number of harvested trusses. However, in both varieties the stem was shorter than the standard crop. After leaf picking from the head was stopped, the difference in length remained stable.
Research Wageningen UR Greenhouse Horticulture
In the same year research was also done in test greenhouses at Wageningen UR Greenhouse Horticulture in Bleiswijk, with largely similar results. This growing season Wageningen UR started a new study. So far no production differences have been detected.