The influence of air temperature on truss weight of tomatoes

Data for fruit production of tomato, cli. Dombito, grown during the period 1987 to 1994 in Greece and the U.K., and cv. Solairo grown in 1997 in the U .K., have been coupled with continuous records of glasshouse air temperatur e and solar radiation, in an attempt to produce a basis for improving yield . The plants were grown using soilless culture, and produced fruit from 20 tr usses in the period from December to June in Greece and up to 27 trusses fr om March to December in the U.K. Most of the yield data were linearly relat ed to accumulated solar radiation reaching the plants. With Dombito however , which was grown with mean air temperatures during the truss growth period in the range from 12 degrees C to 26 degrees C, the results for 2 out of 8 batches of plants were non-linear. Extremes of temperature had resulted in lower truss weights. Solairo was grown in a heated glasshouse, with a rang e of mean air temperatures during the truss growth periods from 18.4 degree s C to 21.8 degrees C. Over this range of temperatures, truss weight decrea sed linearly with increase in temperature. The data suggested that for Sola iro, instead of having glasshouse air temperature control based on set poin ts, the aim of heating and ventilating control should be to produce a 24-ho ur mean air temperature as near as possible to 18 degrees C.