| Περίληψη: |
Sweetpotato (Ipomoea batatas L.) produces edible roots and leaves, which may offer two crops from the same plant for direct-market farmers. Other studies indicate that harvesting sweetpotato greens impacts root yield negatively; however, little is known about how the timing of the greens harvest changes the impact on root yield. Furthermore, it is not known whether the decrease in root yield may be offset economically by an increase in greens yield. A field study was conducted in Mount Vernon, WA, USA, in 2023 and 2024 to evaluate greens and root yield of three sweetpotato advanced breeding lines (USDA-04-136, USDA-04-284, and USDA-04-791) being evaluated for potential cultivar release. The study included four greens harvest schedules: early [greens harvest at 8, 10, 12, and 16 weeks after transplanting (WAT)] mid-late (greens harvest at 12, 14, and 16 WAT), continuous (greens harvest at 8, 10, 12, 14, and 16 WAT), and late (greens harvest at 16 WAT, just before root harvest; control). For each greens harvest, 15-cm vine tips were cut from all vines that were at least 15 cm in length. Greens harvest in the early, continuous, and mid-late harvest treatments reduced canopy cover. Greens yield was greatest for the early and continuous harvest treatments and averaged 4.02 t.ha-1 for the three breeding lines. Greens fresh weight peaked at 10 WAT, but production continued throughout the season, suggesting that repeated greens harvest at 2-week intervals is suitable for this region. Harvesting sweetpotato greens decreased total root yield by 47%, 54%, and 37% for the early, continuous, and mid-late harvest treatments, respectively. However, the decrease in root yield was offset by the greens yield in the continuous harvest treatment, and gross economic returns were similar for the continuous and late harvest treatments when greens were sold at $3 per bunch (20 stems) and roots were sold at $6.60 per kg ($3 per lb), which was common for direct-market growers in Northwest Washington. Thus, dual-cropping sweetpotato for greens and roots may be economically viable for direct-market farmers. [ABSTRACT FROM AUTHOR] |