Vegetable Transplant Production
Evaluating the Impact of Transplanting Depth on Tomato Yield
by Charles Vavrina
Because of the statewide success by researchers in consistently increasing bell
pepper yield by increasing transplant depth, the next logical step was to see if
this phenomenon occurred in tomatoes. With the help of Phyllis Gilreath, Manatee
County Extension and Steve Olson, North Florida Research and Education Center, the
hypothesis was tested statewide. The studies were set out with Agriset in Immokalee
and Manatee under seepage irrigation, and Colonial and Sunny in Quincy under drip
irrigation. All crops were on polyethylene mulch in the spring of 1994.
Tomato yield (mature green) increased as planting depth increased at first and third
harvest, and in combined harvest total yield (Fig- 1). A 26 percent increase in
25 pound boxes of fruit was found at first harvest by planting transplants to the
first true leaf, when compared to just covering the root ball. With all harvests
combined, plants transplanted to the first true leaf showed an 18 percent increase
in total yield. Transplants planted to the cotyledon leaf produced yields intermediate
between the root ball and true leaf plantings.
Figure 1. Tomato planting depth yields of Agriset mature green fruit. Immokalee,
Extra-large fruit volume was increased at first harvest by deeper planting (Figure
2). Extra-large fruit volume was greatest for the deepest planting and was significantly
less for the cotyledon and root ball plantings. The extra-large fruit response appeared
to be a first harvest phenomenon as the other treatments "caught up" after four
harvests. Sunny did not show the same response as Agriset and Colonial, implying
different cultivars may respond differently to planting depth. This aspect is undergoing
Figure 2. Effect of planting depth of early yield size distribution of Colonial
tomatoes. NFREC, Quincy 1994.
The investigation into tomato planting depth continues this fall with trials in
Manatee, Collier and Dade counties. While trial conclusions were not identical at
every site, they were similar enough to suggest that planting tomato transplants
to the first true leaf will result in larger fruit yields and more extra-large fruit
especially at first harvest.