Plants need sunlight to grow, but let’s be more specific – plants need visible light to grow. What do we mean by this statement?
Sunlight is made up of 3 main components: visible light, ultraviolet radiation (UV) and infrared radiation (IR).
Visible light is beneficial for plants and is required for photosynthesis – the process whereby energy from sunlight is converted into nutrients and energy for the plant, too much UV radiation on the other hand can be detrimental.
What is ultraviolet (UV) radiation?
Ultraviolet (UV) radiation is a type of electro- magnetic radiation with a shorter wavelength that makes up about 10% of the electromag- netic radiation output from the sun.
UV radiation is divided into 3 ranges: UVA, UVB and UVC. UVA and UVB are not absorbed by the ozone layer while UVC is completely absorbed by the ozone layer. UVA radiation is typically associated with tanning as UVA rays are lower in energy but penetrate tissue more deeply, while UVB rays are associated with burning as UVB rays are higher in energy.
Why is UV radiation relevant in plant production? Cue: leaf scorch, sunburn browning and sunburn necrosis
Leaf scorch occurs when roots are unable to supply ample water to the foliage as rapidly as it is lost by transpiration and is typically characterised by browning of the leaf margins with yellowing of the areas between the main leaf veins resulting in the leaves becoming dry and brittle.
Sunburn browning, as a result of joint exposure to high surface temperature and UVB radiation, is less severe as it does not lead to cell death, but still stresses the plant.
Sunburn necrosis typically affects fruit and is due to high fruit surface temperature resulting in thermal death of the fruit cells leading to necrotic spots on the fruit.
So what is RayBlock™ and how does it work?
RayBlock™ is a kaolin clay-based product for foliar applications which provides protection against UV damage to a wide range of crops. It is a natural, biodegradable sunscreen designed to protect crops against leaf scorch, sunburn browning and sunburn necrosis.
Under hot conditions plants transpire more rapidly, leading to more rapid evaporation of water through the stomata. When the rate of transpiration is too high, then the rate of water loss is also too high, and the plant becomes stressed.
Application of RayBlock™ forms a thin film on the plant surface which acts as a reflective barrier that is able to reduce the amount of heat that the plant absorbs, which decreases the rate of transpiration when compared to untreated plants.
This in turn decreases the rate of water loss which results in reduced heat stress as the plants remain cooler and hydrated for longer, helping to prevent leaf scorch, sunburn browning and sunburn necrosis
Rayblock™: Reg. no. B 6624 Act No. 36 of 1947
Active ingredient: Silicon (Si) – 243,0 g/kg / Potassium (K) – 16,1 g/kg / *CONTAINS A PLANT-AVAILABLE SILICA. RayblockTM is a trademark of N Laboratories (PTY) LTD. Reg. no: 2015/165672/07. Marketing and distribution by: MBFi (PTY) LTD. Reg no: 2013/211882/07. Box 1137, Delmas, Mpumalanga, 2210. orders@mbfi.co.za, www.mbfi.co.za.
