Yield and Quality of Snap Bean (Phaseolus vulgaris L.) Cultivars from Successive Harvests in Spring and Fall Production Seasons in Oklahoma

Numerous studies have evaluated snap bean pod yield and quality at different pod maturities, but only a few have evaluated yield and pod quality across different seasons within the same year or for pods harvested at the same relative maturity successively from the same plants. Hence, the aim of this study was to determine if snap bean yield or pod sugar accumulation differed for pods at the same relative stage of maturity from plants harvested multiple times in spring and fall planting seasons in north central Oklahoma. Nine snap bean cultivars (seven green-podded and two yellow-podded) were field-grown in Spring and Fall 2022 and 2023. Pods were harvested weekly for 3 weeks from the same plants and at the same relative pod development stage. Pod yield and sugar concentration were measured. The total pod yield pooled across seasons and years of ‘Sybaris’ was lower (approximately 4100 kg⋅ha −1 ) than that of six of the other cultivars, which yielded between 7000 to 8600 kg⋅ha −1 . In spring, pod yield increased from 900 to 1300 kg⋅ha −1 in the first harvest to 3500 to 3700 kg⋅ha −1 by the last harvest. In Fall 2022, the yield decreased from 1900 kg⋅ha −1 in the first harvest to 690 kg⋅ha −1 by the last harvest, whereas in Fall 2023 the pod yield remained steady at 2600 to 3000 kg⋅ha −1 at each weekly harvest. The Fall 2022 decrease in yield was likely caused by low temperatures during pod development and a freeze that shortened the harvest season. From the first to the last harvest, the total pod sugar concentration decreased from 145.5 to 107.2 mg⋅g −1 , glucose decreased from 48.4 to 33.0 mg⋅g −1 , and fructose decreased from 90.7 to 52.0 mg⋅g −1 . However, the sucrose concentration increased from 9.2 to 21.9 mg⋅g −1 . This decrease in the total and monomeric sugar concentrations, coupled with a disproportionally smaller increase in sucrose, is typical for overly mature snap bean pods, which are considered less desirable because of lower sweetness. Snap bean pods harvested later in the growing season in a successive harvest system at the same relative stage of maturity as earlier harvested pods had sugar concentrations resembling those of overly mature pods, indicating that snap bean plant age may influence the pod sugar concentration.