MODEL OF CUCUMBER GROWTH AND PREDICTION OF YIELDS

Several cucumber growth models have been built in recent years. Most of them deal with the early phases of crop growth. Models concerning the phase of fruiting plants have to consider some special difficulties. Some of them were reported in Acta Horticulturae No. 118.

To predict yields (e.g. number of fruits per week) one has to realize the increasing length of this phase and thus the increasing number of sources of variance. In 1975 experiments were started in Hannover to examine the effects of temperature and radiation. More than 1500 data were recorded with an average of 1.89 ± 1.35 fruits of first grade per week (coefficient of variability = 71%). Results of regression analysis indicated temperature to be less important than radiation and plant age.

Using equations derived from multiple regression analysis about 50% of variability could be explained. The increasing importance of other factors like water and nutrient supply or plant protection may be concluded from this figure. Another problem was to elaborate parameters and coefficients that allow reasonable predicting of yield not only in the middle of the response surfaces but also at its outer areas. With different methods attempts have been made to overcome these problems.