Microtomato Fruit Production Varies among Cultivar and Photosynthetic Photon Flux Density in an Indoor Vertical Production System

Seven microtomato ( Solanum lycopersicum L.) cultivars were initially screened for appropriate heights adaptable to indoor vertical rack systems. Of the seven tested, two (29%) exceeded the height limit to fit within indoor racks even though they were described commercially as microtomatoes. Of the five within the height limits, ‘Micro Tom’, ‘Venus’, and ‘Jochalos’ were selected as test cultivars and grown in vertical racks at photosynthetic photon flux densities (PPFDs) of 260, 350 and 430 μmol·m –2 ·s –1 , with a 16-h photoperiod. Cultivar and PPFD affected plant height. Plant height ranged from 11.8 to 12.8 cm across cultivars, and 11.8 to 12.5 cm across PPFDs, with plants grown at a PPFD of 430 μmol·m –2 ·s –1 being shorter than those grown under PPFDs of 260 and 350 μmol·m –2 ·s –1 . Cultivar affected days to first flower and first harvest, with ‘Micro Tom’ flowering and fruiting sooner than ‘Venus’ and ‘Jochalos’, although days to fruit harvest varied by only 3 days across the cultivars. Days to first flowering was affected by PPFD, but did not affect days to first harvest. There was a significant interaction between cultivar and PPFD for the number of fruit harvested. Total fruit number across all treatment combinations ranged from 50 to 96. Total fruit number increased for ‘Micro Tom’ as PPFD increased from 260 to 350 and 430 μmol·m –2 ·s –1 , but fruit number was not different for ‘Jochalos’ and ‘Venus’ across PPFDs. Cultivar affected total fruit weight, which ranged from 265.8 to 347.5 g, with ‘Jochalos’ having a greater total fruit weight than ‘Micro Tom’ and ‘Venus’, and ‘Micro Tom’ having a greater fruit weight than ‘Venus’. Fruit weight was affected by PPFD and ranged from 272 to 320 g, with plants grown at a PPFD of 350 and 430 μmol·m –2 ·s –1 having a greater fruit weight than those grown at 260 μmol·m –2 ·s –1 . Fruit Brix was affected by cultivar and PPFD, with an increasing PPFD resulting in a greater fruit Brix.