ISHS Acta Horticulturae 156: XII Working Party on Greenhouse Cucumbers
MODEL OF CUCUMBER GROWTH AND YIELD I. RAISING THE CROP UNDER LOW TEMPERATURE REGIMES |
| Author: | H.-P. Liebig |
| Abstract:
Results of earlier experiments indicated low temperature set points of the heating system of 20° C day and 16° C night to be superior to set points of - 22° C. To improve modelling of crop growth more investigations concerning the effects of lower temperature regimes especially the low temperature limits were needed. In 1981 several experiments were started in Hannover to examine the action of low temperature regimes. Grafted and ungrafted plants (c v. 'Pepinex') were tested at air temperatures ranging from 10° C to - 20° C using unheated soils. Minimum temperature requirements were determined to be 14° C. It became evident that low soil temperatures are more growth limiting than low air temperatures. Grafted or soil heated plants survived at 10° C air temperature, but severe wilting and chlorosis occurred if longer periods were taken into account. With just superlethal temperatures stem elongation rates were drastically reduced. But no after-effects could be found once the production had started again after the temperature had been raised to 18° C. Soil heating or grafting are recommended to overcome short term periods of low air temperatures, substitution of suitable air temperature cannot be achieved. | |
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