Page 189 - PC2019 Program & Proceedings

PLANT CANADA 2019

S163. Adapted crops for the low light indoor environment: a concept for year round sustainable
gardening in the home with potential for commercial greenhouse production
1
2
Tanino, K. ; E. Benic ; M. Nair
1
1 University of Saskatchewan
2 LLT Plants Inc.
Commercial greenhouses can offset power costs by either growing crops which are low light adapted and
do not require high irradiance conditions, or through double cropping. Vegetable and fruit cultivars have
been traditionally bred and selected under high light conditions in the greenhouse or under full sun
conditions in the field. Nevertheless, there appears to be a large genetic variation for adaptation to low
irradiance conditions within existing commercial vegetable cultivars. Over 55 crops/cultivars were
screened for potential commercial greenhouse production. Several crops show promise including a cool
temperature adapted Brassica japonica cv. ‘Kyoto Mizuna’ examined in a commercial greenhouse
environment. Furthermore, the limiting factor to producing plants year round indoors on home and
school windowsills is not heat, but light. After 38 years of breeding, a Low Light Tolerant lemon and
lime were developed: ‘First Canadian’ lemon and ‘First Canadian Golden’ lime, producing up to 12 – 15
commercial size lemon fruit/plant in a 15-cm pot on the windowsill. Microgreens are also an important
first step introducing growing and consuming fresh greens to children in schools. Collectively, these
plants have potential to introduce children to the idea of growing and eating tasty horticulture crops year-
round since plants can be produced indoors in the classrooms during the school term.

Karen Tanino (karen.tanino@usask.ca)

S164. Cultural and genetic approaches for improving the response of greenhouse vegetables to
extended photoperiod and supplemental lighting
Orozco, M.E.; T.R.J.G. Marie; M. Micallef; B.J. Micallef
University of Guelph

The three major greenhouse vegetable crops, including tomatoes, peppers and cucumbers, all show some
susceptibility to photoperiodic injury (PI). PI is characterized by chlorosis of vegetative tissues when
grown in extended photoperiods or non-24 h light-dark cycles. This phenomenon can limit the efficiency
in which greenhouse vegetable crops respond to supplemental lighting (SL) during the winter months, and
particularly when photoperiod extension is required to make SL economically feasible, such as in Ontario.
We have shown that PI in greenhouse vegetable crops is linked to nitrate uptake and assimilation and the
circadian clock. By establishing the physiological basis for PI in greenhouse crops, we have developed
cultural and genetic approaches to reduce PI and improve the response to supplemental lighting. Three
cultural methods that will be discussed include the use of: (1) specific time-of-day patterns of SL; (2)
time-of-fertigation techniques and altered nitrate fertilization; and (3) altered light spectrum. Some of
these approaches have been tested in commercial greenhouse operations in Leamington, ON, including
tomato and cucumber operations. Variation does exist in the severity of PI among existing cultivars of
greenhouse and field tomato and greenhouse cucumber, and our group has shown that two genes affect PI
in tomato. The potential and limitations in breeding greenhouse vegetables that show an improved
response to supplemental lighting will also be discussed.

Barry Micallef (bmicalle@uoguelph.ca)

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