Height Control in Three Pepper Types Treated with Drench-applied Abscisic Acid

Abstract

Vegetable transplants can have excessive internode elongation before field establishment, producing challenges for the growers using mechanical transplanters to establish their crops. Thus, controlling the height of vegetable transplants before planting could be an advantage for commercial vegetable growers. A greenhouse experiment was conducted in 2008 (Year 1–2008) and 2009 (Year 2–2009) to determine the efficacy of exogenous drench-applied abscisic acid (ABA) applications for height control of transplanted pepper. Three types of pepper (Capsicum annuum L.) were investigated: bell pepper ‘Aristotle’, Jalapeño ‘Grande’, and banana pepper ‘Pageant’. In this greenhouse study, 10 ABA treatments, based on application frequency and timing, and an untreated control were arranged in a randomized complete block design with six (Year 1–2008) or five (Year 2–2009) replications and were evaluated over an 8-week period each year. Treatments included: single application at Week 1 (cotyledon stage), Week 2, Week 3, and Week 4; double applications were made at Weeks 1 + 2, Weeks 2 + 3, and Weeks 3 + 4; and multiple applications of ABA at Weeks 1 + 2 + 3, Weeks 2 + 3 + 4, and Weeks 1 + 2 + 3 + 4. All ABA applications were delivered as a drench applied directly to the planting container at a rate of 250 mg·L−1 ABA. Early, single-dose applications (Week 1) were more effective at controlling height than a single dose applied later; a Week 1 application measured during week 5 was 4.1 cm versus a Week 4 application measured at Week 5, which was 5.7 cm. Multiple ABA applications initiated early (at the cotyledon stage) of ‘Aristotle’ bell peppers were effective in controlling transplant height compared with any single ABA application; measured at Week 5, an application at Week 1 + 2 was 3.1 cm compared with the single application treatments from that same measurement date, which ranged from 4.1 to 5.7 cm. Differences among the response of pepper types to ABA application were observed. ‘Aristotle’ had significant treatment effects even 6 weeks after treatment. ‘Pageant’ (banana pepper) exhibited an intermediate response with effects lasting only 2 weeks. No significant height reductions resulting from ABA treatment were observed for ‘Grande’ (Jalapeño pepper). Multiple ABA dose applications initiated at the cotyledon plant growth stage can be used to effectively control transplant height of ‘Aristotle’ bell pepper seedlings.