Vigour of greenhouse tomato plants (Lycopersicon esculentumMill.): Analysis of the criteria used by growers and search for objective criteria

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SummaryIn greenhouse tomato crops, growers examine the “vigour” of the plants to choose cultivation techniques, but their observations are subjective. We aimed to determine what growers mean by vigour and to identify objective criteria for measuring it. Two trials were conducted, in 1994 and 1996. For both, four growers were asked to give a vigour score to each plant in the trial, and this was compared with agronomic variables such as leaf area, plant dry weight, stem diameter and fruit yield. The main criteria growers observe are stem diameter and internode length, on the top of the plant, between the apex and the flowering truss. They also take into account foliage colour and habit. Vigour scores and vegetative measurements were well correlated (r from 0.6 to 0.9). Therefore, although the growers’ definition of vigour is subjective, it characterizes the vegetative plant state. In particular, the vigour score was correlated with the measurement of stem diameter. Vigour on one occasion was correlated with the mean weight of the fruits harvested two and a half months later. This suggests that growers can use vigour to determine which cultivation techniques to apply to modify plant habit and fruit size.