Effect of transplanting date on the phenology and production of 4 tomato (Lycopersicon esculentum Mill.) hybrids grown under greenhouse

Early production is an important issue in many areas of greenhouse tomato production. Studying the behavior of new cultivars and the relationships among transplant characteristics and their productivity after transplant could help to improve early yields. The aims of this work were to evaluate the relationship among seedling characteristics at transplant and ambient conditions during nursery time, and the effect of seedling characteristics on early fruit production. Four indeterminate growing habit tomato hybrids: Sofia, Silvana, Badro and Superman were sowed on 3 dates during 2007: June 2nd, July 14th and August 1st and transplanted on: July 25th, August 17th and September 18th respectively, to a parabolic greenhouse placed in La Plata, Buenos Aires, Argentine (34°55’ S, 57°57' W). Plant height, leaf area, dry weight, number of expanded and none expanded leaves and position of the inflorescence was measured at transplant. After transplant it was registered flowering, fruiting and first harvest dates. Fruits harvesting from the two first trusses were considered as early yield. Average, maximum and minimum daily temperatures were recorded from sowing to harvest inside the greenhouse. The experimental design was a complete randomized block, with 3 x 4 factorial arrangement and 3 replications. Analysis of variance was performed and means differences were compared by Duncan multiple range test. At transplant, inflorescence differentiation was achieving by seedlings from the three sowing dates. Plants from the third sowing were exposed to higher temperatures during nursery time, achieving the highest plant size. Later transplant dates reduced the number of days to first harvest in all hybrids, with highest early production during the first date, prevailing small fruits; meanwhile, individual larger fruits were obtained during the third date of transplant.