Dissertation
MAXIMIZING POTATO QUALITY AND MARKETABLE YIELD OF FIVE CULTIVARS BY ASSESSING EVAPOTRANSPIRATION, REFINING CROP COEFFICIENTS, AND REDUCING LATE-SEASON IRRIGATION
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000002427
Handle:
https://hdl.handle.net/2376/120868
Abstract
This study was conducted to determine whether reduced late-season irrigation improves tuber quality while maintaining yield and to investigate evapotranspiration (ETc) differences and develop crop coefficient (Kc) values of five potato cultivars: Alturas, Clearwater Russet (R.), Ranger R., R. Burbank, and Umatilla R., The effects of reduced late-season irrigation and evapotranspiration measurements were investigated from 2018 to 2020 at the WSU-Othello research farm under over-head irrigation. Based on modeled evapotranspiration (ET) recommendations, different irrigation levels (ILs), 40%, 60%, 80%, 100%, and 120% ET, were implemented at approximately 1500 day-degrees, between 95 and 110 days after planting. This timing was chosen to investigate if irrigation could be reduced below ET once the canopy and roots had reached their developmental peak. ETc was measured using a combination of environmental and soil sensors and the soil water balance method. Reducing irrigation below 100% ET during the latter half of the season significantly reduced the total yield of all cultivars. Grower return was maximized for four cultivars when soil moisture was replaced at 100% ET; however, grower return for Alturas peaked at 80% ET. A significant positive linear relationship was found between the ILs and growth crack incidence in Alturas. For all cultivars, a significant negative relationship was found between the ILs and tuber specific gravity. Tuber fry color improved when late-season irrigation was reduced on all cultivars except for Ranger R., enabling tubers to be stored at colder temperatures; this is highly desired by the frozen-processing industry. Lastly, season-long crop evapotranspiration (ETc) significantly differed among the five potato cultivars, with Alturas and Clearwater R. producing the highest evapotranspiration rates during the mid-season. Furthermore, using the five cultivars’ ETc measurements, Kc values were developed, with average Kc values of 0.4, 0.95, and 0.57 for initial, mid-season, and late-season stages, respectively. These findings provide growers with storage and production options and incentives to reduce water consumption while maximizing profits from higher-quality tubers.
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Details
- Title
- MAXIMIZING POTATO QUALITY AND MARKETABLE YIELD OF FIVE CULTIVARS BY ASSESSING EVAPOTRANSPIRATION, REFINING CROP COEFFICIENTS, AND REDUCING LATE-SEASON IRRIGATION
- Creators
- Francisco Gonzalez Tapia
- Contributors
- Mark J. Pavek (Advisor)Lynne A. Carpenter-Boggs (Committee Member)Norman R. Knowles (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 240
- Identifiers
- 99900606756601842
- Language
- English
- Resource Type
- Dissertation