Applied Plant Biology London Fieldcourse 2018 – Part 3

Tozer Seeds & Chelsea Physic Garden

by Elizabeth Vanveen (3rd Year Applied Plant Biology)

This day differed from previous ones throughout this field trip as it involved visiting two different companies. The first half of the day was dedicated to visiting Tozer Seeds, the largest independent family business selling vegetable seeds in the UK. This event commenced with a presentation that explained the company’s goals and ideals. Although Tozer began as a local company, it is now multinational with offices present around the globe such as that of Santa Maria in California, and Murcia in Spain. Plant breeding is at the heart of this company which has also been central to human civilisation for over 10,000 years (Lev-Yadun et al., 2000). By utilising the plant breeding skills adopted and used by humans throughout history, Tozer Seeds strives to develop innovative products with excellent flavour and good field performance. The seeds produced are sold directly to packet seed companies or grocery growers.

Tozer produces seeds from both obligate self-pollinating plants and cross pollinating plants. The top seller of this company is parsnip seeds. Parsnips are an example of a plant can exhibit cytoplasmic male sterility; a maternally inherited condition in which a plant is unable to produce functional pollen (Schnablea and Wiseb, 1998). This is particularly useful for hybridisation as the flowers cannot self-pollinate and eliminates the need for mechanical emasculation. Therefore male-sterile plants can be crossed with wild-type male-fertile plants to produce heterozygous hybrids with increased hybrid vigor. Due to the cytoplasm of a zygote usually being inherited by female gametes (male-sterile plant), the progeny will remain sterile. This acts as a form of security for Tozer as the seeds must be rebought. Similarly Tozer also produces F1 hybrid seeds. Selective breeding is also utilised to create new plant varieties, however this is a time consuming process that can take anywhere from 15 – 20 years to reach a desired outcome.

Following this presentation a tour was carried out through the premises beginning with the seed germination room. One particular project being carried out was testing for mildew tolerance in seedlings. Those seeds that appeared to be resistant will go on to be grown in field conditions, and homozygous / uniform individuals will be selected. The process is then repeated until resistance is and homozygosity is achieved. The seed washing station was also observed. Seed washing is necessary for those seeds that are prone to pathogens, however this comes with challenges as moisture typically reduces seed longevity (Vertucci and Roos, 1990). Therefore thorough drying of seeds follows the washing stage. The tour continued through to the glasshouses. Where a number of different plants were being growing at different stages of development. Amongst the most abundant plants on site were celery, peppers and basil. Of the plants growing here only those exhibiting homozygosity will be pollinated. The pollination stage is carried out by hand and plants are then tagged identifying the family, plant number and age. The final stage in this tour was to the seed storage area where a range of machines are utilised to clean and grade the seeds by weight and size. After this point the seeds are packaged, labelled and dispatched.

Although Tozer Seeds is involved in work that is similar to that of Syngenta, both companies contrast greatly. For example, Tozer utilised biological control in their glasshouses while Syngenta has recently moved away from these methods of crop protection, and focusses on agrochemicals. The ethos of both companies also differs with Tozer being of a smaller scale, with more simplified apparatus’ and being family rooted. Despite both companies being multinational, Tozer is strongly rooted in the UK.

The second half of this day was spent at Chelsea Physic Garden, a three and a half acre garden growing approximately 5,000 different plant species. The garden was initially established by the apothecaries as a place to study medicinally important plants and learn to accurate identify different species. At present however, the garden holds an arrangement of useful plants including those that are edible, poisonous and medicinal. The different plants are subdivided into different areas throughout the garden.

The conservatory holds a number of cacti and succulents which are typically watered only once every two weeks. Alongside these plants which have evolved to deal with drought, there are also an arrangement of plants that have evolved to live on nutrient poor soils. These are carnivorous plants which meet much of their nitrogen requirements through the capture of insects by either passive traps (pitcher plant) or active traps (sundews).

One other particularly interesting area within the garden was a bed containing an arrangement of poisonous plants. Unpalatability is an evolutionary strategy against herbivory which remains a problem particularly for children. In 2012, the US poison control centres reported that over 30,000 potential exposures of children under the age of five to toxic plants were reported (Mowry et al., 2012). Therefore accurate identification of poisonous plants is particularly important to avoid poisoning, particularly because many poisonous and edible plant have similar physiology. The plants within this area included the mandrake and the deadly nightshade (Atropa belladonna).

A number of plants that are poisonous are also of medicinal value which can be clearly observed in Chelsea Physic Garden as T. baccata is found in both the poisonous and medicinal gardens due to its anti-cancer qualities (Rowinsky and Donehower, 1995). Other useful medicinal plants exhibited in the garden include the opium poppy (Papaver somniferum) and star anise (Pimpinella anisum). The tour also included a guide through an evolutionary glasshouse containing a range of bryophytes and ferns, a tropical glasshouse containing many important plants including Cinchona (source of antimalarial quinine), and dicotyledonous order beds containing plants arranged by family. The final area visited during the tour was the garden of useful plants which displayed plants such as bamboo and sunflower.

Chelsea Physic Garden typically gives good insight to plants that are or have been of interest to human civilisation in an approachable manner by subdividing the garden. This garden may have some similarities to Kew Gardens in terms of horticulture, however Kew would be of greater interest to an individual who cares for ecology and conservation. Chelsea Physic Garden would be best suited to an individual with an interest in taxonomy and medicine.

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