The influence of ethephon application to processing tomato plants on yield structure in relation to weather conditions during the growing period

The aim of the study was to evaluate the effect of ethephon application (Agrostym 480 SL) on the yield and yield structure of five processing tomato cultivars (Rumba, Hubal, Sokal F₁ , Mieszko F₁ and Polset F₁ ). The experiment was carried out in the open field in the years 2009-2011 in Mydlniki near Kraków, Poland. Two weeks before harvesting, half of the plants of each cultivar were treated with Agrostym 480 SL (3 dm³ ha^-1) and the other half were left as a control without spraying. Marketable yield included properly shaped and welldeveloped light red and red fruits. Non-marketable yield included pink and turning fruits, mature green and breaker fruits, and diseased fruits. A generalized linear model (GLM) for Poisson distribution with the log link function was used to determine the relationship between the years of the study and cultivar and selected values of the yield structure. The yield structure of tomato depended significantly on the weather conditions during the growing period in different years of the study, on the cultivar, and on the use of ethephon. Ethephon had a particularly beneficial effect on yield structure in the years with an unfavourable distribution of precipitation. Ethephon application in the years 2009 and 2010 had a beneficial effect on the health of tomato plants.