Effets de la fertilisation azotée et des conditions d'application de l'éthéphon sur la productivité de la tomate de transformation cv. Heinz 2653

Processing tomato crops (Lycopersicon esculentum Mill. 'Heinz' 2653) were grown during the years 1986–1988 to study the effects on fruit yield of side-dressed N rates (45, 90 or 135 kg N ha −1 ), ethephon spraying date (early or late) and dose (3.5 or 5.5 L ha −1 ). Total fruit production in 1987 was much higher than in 1986 and 1988. Early ethephon application increased by 6% the weight of #1 fruits which became more numerous, although smaller in size. The effect of the ethephon application date on yield was subject to production characteristics particular to each year. On the other hand, the effect of the ethephon dose was constant regardless of yearly conditions. The high ethephon dose did not significantly improve #1 fruit yield. Increasing N rate enhanced foliar N content but did not modify yield. It is suggested that N originating from sources other than the banded fertilizer maintained sufficient N levels for optimal growth. Key words: Ethrel, Lycopersicon esculentum, quality, ripening, yield, 2-chloroethylphosphonic acid