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7.21.20 Ertle Thesis Final.pdf (1.06 MB)

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Effects of Short-term Chilling Stress on Seedling Quality and Post-transplanting Growth of Grafted and Nongrafted Watermelon

Ertle, John Michael
http://rave.ohiolink.edu/etdc/view?acc_num=osu1594742774066127

Abstract Details

2020, Master of Science, Ohio State University, Horticulture and Crop Science.
In recent years, the North American region has seen increased usage of grafted vegetable transplants to reduce soil-borne disease incidence, increase tolerance to abiotic stress, enhance fruit quality, and increase yields over conventional nongrafted transplants. Grafting itself is a unique agrotechnology that merges a vegetable crop (scion) with the root system of another plant (rootstock) to form one transplant that benefits from both traits. In North America, a recent survey showed nearly 60 million grafted transplants are produced annually for fruiting vegetable crops, including tomato, watermelon, cucumber, pepper, eggplant, and muskmelon. Due to the limited number of nurseries in North America, transplants are commonly shipped 3-5 d to distant producers and have reportedly experienced chilling stress during transportation that reduces transplant quality and may affect post-transplanting performance. However, few studies have explored the specific effects of transport-related chilling stress on seedling quality and post-transplanting development. Using watermelon (Citrullus lanatus), a highly chilling sensitive member of the Cucurbitacea family, we examined effects of acute chilling stress on seedlings quality and post-transplanting development. When grafted and nongrafted seedlings were exposed to 0 - 48 h of 3 °C chilling, we found that seedling quality and post-transplanting development were unaffected by chilling. However, when the chilling temperature was reduced to 1 °C, seedlings exhibited increased visual damage of seedlings with longer durations, decreased chlorophyll fluorescence (Fv/Fm), and increased delays in the number of days it took for plants to reach male and female flower anthesis after transplanting. Nongrafted plants had longer delays in days to flower anthesis than grafted plants, indicating that grafted plants may have been more resistant to chilling or had enhanced flower primordia development that reduced the effects of acute chilling. Based on these findings, we chilled nongrafted watermelon for various durations at chilling temperatures between -0.4 and 1.2 °C to determine if the chilling stress could be a cumulative response below a specific threshold temperature. Threshold temperatures, or base temperatures (BT), between 3 and 15 °C were found so that various measures of seedling quality were highly correlated with chilling degree hours (CDH). We found that seedling damage and reductions to Fv/Fm were highly correlated with CDH accumulation at base temperatures of 15 and 3 °C, respectively. Further, delays in female flower development increased linearly with CDH when a BT was selected as 4 °C. Therefore, reproductive development was directly inhibited by the chilling temperatures, and 4 °C was a critical temperature that caused post-transplanting reproductive delay. This result was confirmed when using the CDH model to analyze our previous results, indicating that this model can be used to predict delays in plant reproductive development when given various chilling conditions. Our results suggest that long-distance transportation of transplants above 4 °C will allow proper post-transplanting development without delays.
Chieri Kubota (Advisor)
Joseph Scheerens (Committee Member)
Matthew Kleinhenz (Committee Member)
156 p.
Agriculture; Horticulture; Physiology; Plant Biology; Plant Sciences
watermelon; grafting; chilling; physiology; abiotic stress; chilling degree hours; low-temperature; grafted; nongrafted; fruiting vegetable crop; cucurbitaceae; citrullus lanatus; transportation; shipping; flowering; development; seedling

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Citations

  • Ertle, J. M. (2020). Effects of Short-term Chilling Stress on Seedling Quality and Post-transplanting Growth of Grafted and Nongrafted Watermelon [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594742774066127

    APA Style (7th edition)

  • Ertle, John. Effects of Short-term Chilling Stress on Seedling Quality and Post-transplanting Growth of Grafted and Nongrafted Watermelon. 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1594742774066127.

    MLA Style (8th edition)

  • Ertle, John. "Effects of Short-term Chilling Stress on Seedling Quality and Post-transplanting Growth of Grafted and Nongrafted Watermelon." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594742774066127

    Chicago Manual of Style (17th edition)

osu1594742774066127
176
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