Browsing by Author "Chen, Yuqi"

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    Shortening Silphium integrifolium Juvenility and Establishing a Sterilization Protocol for Micropropagation
    (2021-12) Chen, Yuqi
    Perennial crops hold great potential to move towards more sustainable agriculture by offering a long-term solution to the ongoing problem of soil erosion and degradation associated with annual cropping systems. A new candidate to perennial agriculture is Silphium integrifolium Michx (rosinweed), a native herbaceous perennial plant closely related to sunflower. This project aims at exploring the vernalization process to shorten S. integrifolium juvenility, induce precocious flowering, and establish a sterilization protocol for micropropagation to facilitate and accelerate its breeding and domestication process. Current breeding efforts focus on developing populations with improved agronomic traits such as seed yield, seed size, plant stature, and size and number of flowers. An impediment to breeding efforts of Silphium is its delayed flowering, i.e. long term of juvenility. Silphium plants when grown from seed usually have to grow and experience vernalization before flowering the next year. Because of the long period of juvenility in Silphium, the breeding cycle is lengthy, which involves time needed to break the seed dormancy, rosette forming and developing in the first season, and then bolting and flowering in the following season; thus shortening Silphium’s prolonged juvenility period and inducing flowering can help to shorten the breeding cycle and accelerate domestication. This study aims at exploring the vernalization process for S. integrefolium and understanding the age response to vernalization in order to achieve dependable early flowering, which will ultimately shorten its juvenility and enable faster breeding cycles and accelerate its domestication process. We discovered that plants required at least three weeks of cold to consistently induce flowering and as the length of cold treatment increased, time to bolting and flowering after cold treatment decreased. We also determined that young plants needed to grow to the stage of 8 to 10 leaves to be successfully vernalized after 4 weeks of cold treatment. Perennial crops are constantly exposed to fungi and bacteria in their environment, and thus explants from field-grown plants are difficult to disinfect for micropropagation because of both endophytic and epiphytic microbes. Field grown S. integrifolium plants were potted and grown in the greenhouse for five weeks; new stems and anthers along with seeds were tested for in vitro sterilization. We report successful sterilization protocols that involved disinfecting seeds with isothiazolone biocides (PPM) and NaClO and sterilizing stems and anthers through vacuum infiltration of PPM. These protocols should be useful for subsequent micropropagation which could be used to facilitate Silphium breeding and domestication.