REFLECTING PLASTIC MULCH WITH THE CULTURE OF EARLY HEATED TOMATOES IN THE LIGHT POOR WINTER-TIME
Because of the high cost, artificial illumination is not yet considered for a mass application.
In 1961 and 1962 the Institute of Horticultural Engineering experimented with white, light reflecting plastic film as mulch for the culture of heated tomatoes.
With the aid of a spherical heliometer light measurements were carried out a: a height of 30 cm above the light reflecting mulch. From numerous readings was found that the light intensity above the applied white plastic Film was about 30% higher than that above the uncovered soil.
Light measurements with the anthracene method, carried out with the same white plastic film later on, showed about identical results, but still higher values were found above an aluminium film.
On the 1st of February 1961 tomatoes were planted out in a heated glasshouse in the following way (see figure 1) :
South-east partition 7 rows 157 plants, white plastic film
south-west partition 5 rows 185 plants, control-plants
north-east partition 7 rows 252 plants, control-plants
north-west partition 5 rows 180 plants, white plastic film.
On the 21st of December 1962 in 3 repeats double-rows of tomatoes, running north-south, were planted out in a heated glasshouse.
3 Rows of 122 plants on a black film, the same number as control-plants, the same number on a white plastic film and the same number on a transparent plastic film. With regard to the growing results the following can be recorded :
The plants on the white plastic mulch showed an arrangement of leaves bent downwards (the apex of the leaves were directed downwards).
The tomatoplants on the white plastic mulch presented an accelerated and a stronger growth of shoots (From a biological point of view this is interesting).
The plants or the white plastic film flowered earlier. This holds good as well for the flowers of the 1st, 2nd, 3rd as 4th cluster.
The fruit setting on the white plastic mulch of the 1st and 2nd cluster was better than that of the control-plants and that of the plants on the black and transparent plastic mulch.
In 1961 the fruit weight of the tomatoes of the white mulch was higher than that of the fruit of the not covered area.
The harvest of the rows on the white plastic mulch started earlier than that on the black and transparent mulch and of the control-plants.
The accelerated product obtained a higher price.
In 1963 it was observed too that young tomato plants in plastic flower pots reacted favourable upon a white plastic collar, laid around the pot. On the 12th of December, after one month exposure, the fresh weight of the plants, grown up in the plastic pots with white plastic collars, was about 20% higher than that of the control-plants. The plants on the white plastic collar showed again a bent arrangement of leaves (distance to plastic much was Small, see photograph, fig. 2).
In 1965 and 1966 various research stations experimented with white plastic mulch for the culture of early tomatoes. The best results were gained with the very early