Smart glass impacts stomatal sensitivity of greenhouse Capsicum through altered light

Abstract

Optical films that alter light transmittance may reduce energy consumption in high-tech greenhouses, but their impact on crop physiology remains unclear. We compared the stomatal responses of Capsicum plants grown hydroponically under control glass (70% diffuse light) or smart glass (SG) film ULR-80, which blocked >50% of short-wave radiation and ~9% of photosynthetically active radiation (PAR). SG had no significant effects on steady-state (gs) or maximal (gmax) stomatal conductance. In contrast, SG reduced stomatal pore size and sensitivity to exogenous ABA thereby increasing rates of leaf water loss, guard cell K + and Cl - efflux, and Ca 2+ influx. SG induced faster stomatal closing and opening rates on transition between low (100 µmol m -2 s -1) and high PAR (1500 µmol m -2 s -1), which compromised water use efficiency relative to control plants. The fraction of blue light (0% or 10%) did not affect gs in either treatment. Increased expression of stomatal closure and photoreceptor genes in epidermal peels of SG plants is consistent with fast stomatal responses to light changes. In conclusion, stomatal responses of Capsicum to SG were more affected by changes in light intensity than spectral quality, and re-engineering of the SG should maximize PAR transmission, and hence CO2 assimilation.

Smart Glass Film Reduced Ascorbic Acid in Red and Orange Capsicum Fruit Cultivars without Impacting Shelf Life

“…The experiment was conducted in a controlled environment greenhouse facility with east–west orientation located on the Hawkesbury Campus of Western Sydney University, Richmond, NSW, Australia. The four research bays (105 m 2 each) were fitted with HD1AR diffuse glass (70% haze, roof; 5% haze, wall), as previously described [ 13 , 59 ]. Two bays with diffuse glass were designated control bays and two bays (roof and side walls) were coated with SGF (ULR-80, Solar Gard, Saint-Gobain Performance Plastics, Sydney, Australia) and designated as treatment bays.…”

An energy-saving glasshouse film reduces seasonal, and cultivar dependent Capsicum yield due to light limited photosynthesis

“…The facility included four experimental bays (105 m 2 each) fitted with HD1AR diffuse glass on the roof (70% haze) and on the sidewall (5% haze). Two bays were coated with SG film (Solar Gard, Saint-Gobain Performance Plastics, Sydney, Australia) on both roof and side walls and the other two bays were used as "Control' as described previously (Chavan et al 2020;Zhao et al 2021). To investigate the effect of SG and time of planting on capsicum, a 2×2 factorial design was adopted with two cultivars, Orange included six gutters that were 10.8 m (length) × 25 cm (width, AIS Greenworks, Castle Hill, NSW, Australia), and contained 10 Rockwool slabs (90×15×10 cm, Grodan, The Netherlands) as a substrate for plants, per gutter.…”

“…Studies investigating the impact of cover materials are not generally conducted at a commercial scale (Loik et al, 2017; Shen et al, 2021) nor do they comprehensively assess plant growth responses to altered light regimes caused by seasonal change or reduction in PAR (Aroca-Delgado et al, 2019). Recently, we have investigated the impact of light changes on crop growth, photosynthesis, yield, post-harvest fruit quality, and energy assessment using commercial practices of greenhouse vegetable production of eggplant and capsicum in a research facility with the precise climate control of a high-tech commercial glasshouse (Chavan et al, 2020; He et al, 2021, 2022; Lin et al, 2022; Zhao et al, 2021).…”

Energy Minimisation in a Protected Cropping Facility Using Multi-Temperature Acquisition Points and Control of Ventilation Settings

“…Many researchers across continents have compared the energy use between open field cultivation and protected cropping [12][13][14][15]. They have also investigated various heat-filtering film coverings for greenhouse crop production [16][17][18] and developed prediction models of protected cropping energy consumption [19][20][21][22]. These investigations have shown consistent results in response to the effective management of energy consumption through temperature prediction, the introduction of new greenhouse covering materials, glass coatings, and the use of renewable energy sources.…”

“…[16,18] concluded that "Smart Glass" film (commercially available window film ULR-80 that blocks UV and higher light wavelengths which are not used for plant growth but contribute to heat generation) applied to the roof and walls of a greenhouse increase energy and resource use efficiency, without affecting fruit quality. The energy saving was accompanied by certain levels of yield reduction in both eggplant and capsicum crops [16,18]. However, there is still a lack of research investigation on energy analysis in protected cropping from adjustable ventilation and energy-efficient design perspectives.…”