Early Sweetpotato Plant Production Increased by GA3 and BA Plus GA4+7

Abstract

Table 1. Influence of immersion in GA3 or BA + GA4+7 on cumulative number of early z plants harvested Treatments that decrease the interval from bedding to plant harvest or increase the number of sweetpotato [Ipomoea batatas (L.) Lam.] plants produced from bedded roots help reduce propagation cost and facilitate early transplanting. Immersing roots in 250 to 1000 mg/ liter gibberellic acid (GA3) before bedding increased the number of early and total plants produced (Tompkins and Bowers, 1970; Tompkins et al., 1973). However, those plants had thin, tough, wiry stems that could not be satisfactorily. transplanted mechanically (Tompkins et al., 1973). The cytokinin benzyladenine (BA) has been reported to interact with the activity of GA3 (Malik and Archbold, 1992) and GA,.,, the latter in a proprietary material (Miller, 1988). The objective of this study was to determine if using lower GA concentrations than previously reported would increase plant production without the plant distortion reported by Tompkins et al. (1973). ‘Georgia Jet’ and ‘Jewel’ roots were removed from storage on 13 Apr. 1990 and sorted for uniformly large canner size (2.5 to 5 cm in diameter, 5 to 18 cm long). Roots of each cultivar were assigned randomly to lots of 20 and immersed 10 min in solutions of GA3 at 0.5 or 1 mg·liter-1 (Pro Gibb 4%; Abbott Lab., North Chicago, Ill.), in solutions of BA + GA4+7 at 5 or 50 mg·liter -1(Promalin; Abbott Lab.), or not immersed (nontreated control). Roots were air-dried, placed in 40 × 60-cm contiguous plots in a greenhouse, and drenched with a fungicide solution prepared with 16 g of 75% wettable powder 2,6-dichloro-4-nitroaniline (dicloran)/liter. Roots were covered with 5 cm of fumigated Tifton loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudults). The propagating bed was watered immediately after bedding and thereafter as needed to ensure adequate moisture levels for plant production. After the first plant harvest, granular fertilizer [28.0N–12.3P–23.2K