Manipulating table beet growth using exogeneous gibberellic acid 3 in New York, USA

Abstract

Table beet (Beta vulgaris ssp. vulgaris) root suitability for processing into cans and jars is dictated by quality and shoulder diameter (crown width). For shoulder diameter, roots are sorted into six classes and those in the small (19.1–44.5 mm) and small/medium (44.6–40.8 mm) classes are considered suitable. Smaller (≤19 mm) roots are usually lost in harvesting while larger (≥40.9 mm) roots are typically discarded. Exogenous (foliar-applied) gibberellic acid 3 (GA₃) may alter source-sink carbohydrate partitioning with potential advantages for processing table beet producers. Small plot replicated trials were conducted in each of 3 years (2020, 2021 and 2022) to evaluate the effect and optimal timing of exogenous GA₃ on table beet yield components in New York, USA. GA₃ was applied as ProGibb at 30 ppm in all trials and as ProGibb at 30 ppm and FalGro 2X LV at 67 ppm (label rates) in 2022. GA₃ as ProGibb resulted in significant increases in foliar health attributes (leaf blade length and width, petiole diameter, normalized difference vegetative index and dry weight of foliage). GA₃ as ProGibb significantly reduced average root shoulder diameter and affected the percentage of roots in various size categories. The percentage of tiny roots (<19 mm) was significantly decreased while the percentage of small roots was increased. The percentage of small/medium roots were unaffected. In 2022, the percentage of small roots was significantly increased compared to nontreated plots but was not significantly different between GA₃ as either ProGibb or FalGro applied at 42 or 62 Days after Planting (DAP). Exogenous GA₃ had no consistent, significant effect on the severity of the foliar disease, Cercospora leaf spot. The significant increase in foliar health attributes from GA₃ is beneficial for harvest that relies upon top pulling machinery. Increases in the percentage of small roots and reductions in tiny roots can reduce wasted crop input investments. The optimal number of GA₃ applications was seasonally dependent, ranging from a single application at 40 or 62 DAP in 2 years, to two applications in 2021. GA₃ applications late (>80 DAP) in the cropping season had no significant effect on foliar health attributes or root yield components. The implications of these results on the New York table beet processing industry are discussed.