8 research outputs found
Lightâlimited photosynthesis under energyâsaving film decreases eggplant yield
Glasshouse films with adjustable light transmittance and energyâefficient designs have the potential to reduce (up to 80%) the high energy cost for greenhouse horticulture operations. Whether these films compromise the quantity and quality of light transmission for photosynthesis and crop yield remains unclear. A âSmart Glassâ film ULRâ80 (SG) was applied to a highâtech greenhouse horticulture facility, and two experimental trials were conducted by growing eggplant (Solanum melongena) using commercial vertical cultivation and management practices. SG blocked 85% of ultraviolet (UV), 58% of farâred, and 26% of red light, leading to an overall reduction of 19% in photosynthetically active radiation (PAR, 380â699 nm) and a 25% reduction in total season fruit yield. There was a 53% (season mean) reduction in net shortâwave radiation (radiometer range, 385â2,105 nm upward; 295â2,685 nm downward) that generated a net reduction of 8% in heat load and reduced water and nutrient consumption by 18%, leading to improved energy and resource use efficiency. Eggplant adjusted to the altered SG light environment via decreased maximum lightâsaturated photosynthetic rates (Amax) and lower xanthophyll deâepoxidation state. The shift in light characteristics under SG led to reduced photosynthesis, which may have reduced source (leaf) to sink (fruit) carbon distribution, increased fruit abortion and decreased fruit yield, but did not affect nutritional quality. We conclude that SG increases energy and resource use efficiency, without affecting fruit quality, but the reduction in photosynthesis and eggplant yield is high. The solution is to reâengineer the SG to increase penetration of UV and PAR, while maintaining blockage of glasshouse heat gain
Short-term exposure to silicon rapidly enhances plant resistance to herbivory.
Abstract: Silicon (Si) can adversely affect insect herbivores, particularly in plants that evolved the ability to accumulate large quantities of Si. Very rapid herbivore-induced accumulation of Si has recently been demonstrated, but the level of protection against herbivory this affords plants remains unknown. Brachypodium distachyon, a model Si hyperaccumulating grass, was exposed to the chewing herbivore, Helicoverpa armigera, and grown under threeconditions: supplied Si over 34 d (+Si), not supplied Si (-Si), or supplied Si once herbivory began (-Si +Si). We evaluated the effectiveness of each Si treatment at reducing herbivore performance and measured Si-based defenses and phenolics (another form of defense often reduced by Si). Although Si concentrations remained lower, within 72 h of exposure to Si, -Si +Si plants were as resistant to herbivory as +Si plants. Both +Si and -Si ? +Si treatments reduced herbivore damage and growth, and increased mandible wear compared to Si. After 6 h, herbivory increased filled Si cell density in -Si ? +Si plants, and within 24 h, -Si ? +Si plants reached similar filled Si cell densities to +Si plants, although decreased phenolics only occurred in +Si plants. We demonstrate that plants with short-term Si exposure can rapidly accumulate Si-based antiherbivore defenses as effectively as plants with long-term exposure