Sweet colored peppers can yield well in the protected conditions of an unheated high tunnel, but information is lacking about which varieties are adapted for high tunnel production and their performance. During 2018 we evaluated ten sweet pepper varieties at the Purdue Student Farm, West Lafayette, Indiana (Table 1).
How was the evaluation conducted?
The evaluation was conducted on a Mahalasville (Md), silty clay loam. The spring soil test showed 9.5% organic matter, pH 7.5, and 201 ppm phosphorus (P), 250 ppm potassium (K), 810 ppm magnesium (Mg), and 4200 ppm calcium (Ca). The cation exchange capacity was 28.4 meq/100 gram. Micro nutrients tested at 11.5 ppm zinc (Zn), 34 ppm manganese (Mn), 100 ppm iron (Fe), 2.7 ppm copper (Cu) and 2.9 ppm boron (B). Nitrogen, 60 lb. N/A from Nature’s Source® Professional 10-4-3 liquid plant food, was applied by fertigating 15 lb./A N four times at 2, 4, 6, and 8 weeks after transplanting.
The evaluation was set up in a high tunnel that was 30 feet wide and 96 feet long (Fig. 1). The high tunnel was equipped with louvered gable vents (one at each end wall) and rollup side walls. The gable vents were open all the time, but the side walls were opened when inside temperatures reached 75°F and closed when temperatures dropped below 60°F. Peppers were seeded May 7, 2018 and transplanted into raised beds on June 4, 2018 with an in-row spacing of 1.5 feet and between-row spacing of 4 feet. (7,260 plants per acre). The entire area between the raised beds (4 feet center-to-center) was covered with a black woven polypropylene ground cover. Additionally, a 3 feet wide white woven polypropylene groundcover was placed between the rows to increase light in the lower plant canopy. Irrigation was applied once per day using 2 gallon per hour pressure compensated emitters (Netafim), flex vinyl spaghetti tubing and 90 degree angle stakes.
Figure 1. High tunnel layout, 9 weeks after transplanting
The Nature’s Source® Professional 10-4-3 liquid plant food was mixed in a concentrated stock tank at 100 times the normal concentration and injected at a 1:100 rate using a water powered Dosatron D14MZ2 injection unit. Initial plant support was provided with a stake and Florida weave trellis system. The remainder was box stringed. Additionally, plants were treated with a biological fungicide BotryStopTM (BioWorks®) at a rate of 3 lb./A dissolved in 100 gallons water and RootshieldTM (BioWorks®) at 6 oz per 100 gallons water. The treatments were applied through the irrigation system. No pruning was done during the growing season. Weed control was minimal and done by hand. No pesticides were applied during the growing season.
Plots were harvested ten days after the peppers reached their mature color. Harvesting was delayed as a result of a planned field day. Harvesting continued once a week between 92 and 127 days after transplanting. For each plot the marketable and unmarketable number of fruits, fruit weight, fruit size (length and width) and flesh thickness were recorded. During the last harvest (October 9, 2018) all mature colored and mature green fruit were harvested and recorded.
How did the varieties perform?
The yield results are presented in Table 2. Chesapeake produced the highest number of fruits per plant (17.2), followed by Marcato (Fig. 2), Tequila and Flavorburst (Fig. 3). Entries producing significantly heavier fruit included Archimedes (11.07 oz), Blitz (10.73 oz) and Vanguard (10.71 oz). Tequila and Marcato produced the lowest fruit weight, 5.34 and 6.12 oz, respectively. Unmarketable fruit was insignificantly low and are therefore not reported. During harvest some fruits were affected by bacterial soft rot, but did not have a significant effect on yield. No fruit showed any symptoms of blossom end rot.
Figure 2. Marcato just before harvesting
Figure 3. Flavorburst just before harvesting
Delirio produced the lowest yield. The combination of a lower fruit weight and a low number of fruit per plant contributed to the poor performance. There was no statistical difference between the yields of all other entries, which performed well under high tunnel conditions. Chesapeake produced the highest yield. For more information regarding this variety evaluation, download the full report from the 2018 Midwest Variety Trial Report https://ag.purdue.edu/hla/fruitveg/Pages/mvtr2018.aspx.