Research

Environmental factors that influence plant phenotypes include light, temperature, humidity, carbon dioxide concentration, and fertilization. We aim to better understand how plant phenotypes respond to changes in these environmental factors and their interactions. This allows us to 1) determine plant stress responses and 2) identify optimal, efficient environmental conditions for specialty crops in controlled environments. We leverage capabilities of advanced plant growth chambers to generate research insights relevant to indoor vertical farms, greenhouses, and space exploration. Our research focuses on improvements in crop yield (photosynthesis), appearance (morphology and coloration), taste (organoleptic properties), and nutrition (nutrients and phytochemicals) to increase productivity, add value, and conserve resources.

Research highlight

Hydroponic red-leaf lettuce and mustard mizuna grew until maturation in plant growth chambers under different combinations of light wavelengths and carbon dioxide concentrations. M.S. student, Emily Kennebeck, executed the experiment and collected data on plant growth and morphology.

Research sponsored by NASA. Video shot and produced by Dr. Qingwu Meng.

Light conveys energy to drive photosynthesis, constitutes signals to steer morphology, and influences secondary metabolism. Crops grown indoors depend on electric lighting as the sole source of radiation, commonly from light-emitting diodes (LEDs). In a vertical growing system, we use tunable, multicolored LED fixtures to study plant phenotypic plasticity in response to interactions of light quality (spectrum), light intensity (photon flux density), light duration (photoperiod), and plant age. This research aims to develop temporally optimized light regimens that increase light use efficiency, decrease the cost of lighting per plant, and achieve desirable plant phenotypes. In addition, we focus on interactions between light and root-zone factors in indoor hydroponic systems.

Research highlight

Two cultivars of hydroponic hot peppers grew indoors on vertically stacked layers under LED fixtures with different combinations of light wavelengths and intensities. Ph.D. student, Eva Birtell, aims to quantify spectral effects on pepper seedling propagation, vegetative growth, flowering, and fruiting.

Video shot and produced by Dr. Qingwu Meng.

Many floriculture crops flower in response to the photoperiod (daylength). They are categorized as long-day plants (e.g., petunia) and short-day plants (e.g., chrysanthemum). When the natural photoperiod does not elicit desired flowering responses, photoperiodic lighting can be used at night to promote or inhibit flowering. We study how its spectrum, intensity, timing, and duration influence flowering time, stem elongation, flower characteristics, and leaf development. Our goal is to develop low-cost lighting strategies that help greenhouse growers control flowering and extension growth effectively and efficiently. Strategic regulation of flowering can increase greenhouse profitability and sustainability by streamlining crop production and scheduling, saving on labor and resources, and improving crop quality and value.

Crops

We work on a wide range of specialty food crops (e.g., leafy greens, culinary herbs, and fruiting crops) and photoperiodic floriculture crops. With a fundamental understanding of environmental plant physiology, our research generates applied knowledge to help indoor and greenhouse growers address crop production challenges and increase productivity and efficiency.