Vine-Kill Treatment and Harvest Date Have Persistant Effects on Tuber Physiology After Harvest

Authors: Bethke, Paul; Busse, James

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2010
Publication Date: 6/1/2010
Citation: Bethke, P.C., Busse, J.S. 2010. Vine-Kill Treatment and Harvest Date Have Persistant Effects on Tuber Physiology After Harvest. American Journal of Potato Research. 87(3):299-309.

Interpretive Summary: Potato is a high value vegetable crop that is intensively managed. Producing high quality tubers requires careful attention to irrigation, nutrient availability, insect control, and pathogen suppression. These grower activities encourage and sustain the natural developmental progression that leads from tuber initiation to maturation. Vine desiccation and harvest are two grower activities that have the potential to disturb this natural progression and may be detrimental to post-harvest tuber quality. For this research Russet Burbank potato tubers were harvested at early, mid and late season. For the first two harvests, half of the research plots were sprayed with herbicide and half were left untreated. Vine-kill prior to harvest is standard practice in many parts of the US. The data presented here show that vine kill-treatment influences tuber physiology after harvest, and that the effects of vine-kill treatment can persist for several months. Under the conditions of these experiments, the effects of vine-kill treatment on skin set, tuber respiration rates and tuber sugar contents were most apparent when tubers were harvested early. The data also confirm earlier reports showing that harvest date has a major impact on tuber sugar profiles after harvest. Skin set, respiration rate and sugar contents are key physiological parameters that have large impacts on tuber quality, storability, and value coming out of storage. Learning how to better manage harvests to optimize these parameters will have a significant benefit to potato growers, storage managers, and potato processors.

Technical Abstract: Potato tuber development follows a genetically programmed progression from tuber initiation to maturation. Most grower activities nurture this process, but vine kill and harvest are exceptions that have the potential to affect the quality of the crop. Experiments conducted for two years determined the effects of harvest date and vine-kill treatment on the physiology and processing quality of potato tubers stored for up to 12 weeks. Russet Burbank potatoes were grown in central Wisconsin using standard procedures for planting, fertilization, irrigation, and pest management. Tubers were harvested in late July before vines had begun to senescence, in mid-August when limited senescence was observed, and in September after complete natural senescence. Vines were either killed with diquat two weeks prior to the first two harvests or were left untreated. Data were collected at harvest and in storage for skin set, respiration rate, and tuber glucose, fructose and sucrose. Skin set at harvest increased with vine-kill treatment at the early harvest date, but not at the middle harvest date. Significant, persistent differences in respiration rates and sugar profiles were observed for tubers from the different treatments. In particular, the early harvest/vine killed treatment resulted in tubers with respiration rates that were elevated relative to those from the other treatments. Tubers harvested in July after vine kill had lower tuber bud-end glucose than tuber harvested without vine-kill treatment, but stem-end glucose values were comparable. Across treatments, tuber sucrose or glucose content six weeks after harvest was a poor predictor of tuber glucose content twelve weeks after harvest.