8/3/2019 Silicons key role in plant growth

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A and international plant and soil nutritionresearch suggests that low levels of the mineral elementsilicon (i) in its plant available form, is a major deciency

in our soils, particularly where cereal grains, rice and sugarcaneare grown. nd because plants, particularly cereals, are largeaccumulators of silicon during the plants various growth stages,a lot of silicon is transported out of the paddock in the harvestedproduct. s the seasons roll on, the soil reserves of plant availablesilcon (P) are diminished.

What role does silicon play in plant growth?

Plants typically absorb bio-available silicon as a silicate generally known as monosilicic or orthosilicic acid.

ilicon is deposited as silica in the plant cell walls, improvingcell wall structural rigidity and strength, plant architecture andleaf erectness. ilicon in plants can stimulate nutrient uptakeand plant photosynthesis, decrease susceptibility to disease and

insect damage, alleviate water and various mineral stresses anddecrease the toxic effects of aluminium.

P increases the translocation (movement) of nutrients withinthe plant and increases water efciency by reducing transpiration.he benet of a high P content fertiliser product is that itdelivers organic amorphous i (as opposed to crystalline i) in aneasily accessible form to the crop root zone.

here has been extensive research both in ustralia andoverseas investigating the responses of a wide range of crops andsoils to applications of P.

ilicon applications have been shown to break up a compactedsoil to allow air and water to penetrate deeper into the soil,including clays. he water retention has increased via the

better soil structure with some trials showing 35 to 40 per centincreases in moisture retention capability. Japanese study, published in theJournal of Plant Nutrition

in ugust 2008, found that silicon improved hydraulic resistance,allowing the sorghum plants with sufcient P to have a betterwater uptake rate than silicon-decient sorghum under waterstress.

Chinese research, also published in theJournal of PlantNutrition in 2003, studied silicons role in improving wheatdisease resistance. he researchers found that soil-applied Praised the i wheat leaf content and improved the wheat plantarchitecture leading to a higher dry matter yield and reduced spotblotch disease severity.

ilica amendments have also been shown to correct soil

toxicities from high levels of some elements such as Mn(Manganese), Fe (ron) and l (luminium).

For example, a collaborative study by Oxford Brookesniversity in the K and York niversity in Canada (Hadsonand angster) found that sorghum seedlings treated with anl solution had reduced root growth and a signicant increasein the shoot/root ratio. But when silica was included in the lsolution, this signicantly ameliorated the detrimental effects ofl on root growth.

Other trials have shown that high silica absorption by plantsalso helps improve drought resistance while increasing resistanceto fungi and other pathogens. Better growth rates and improvedyields were the result.

n an article published in The Australian Cottongrowerin 2005,

QDP plant researcher inda mith and colleagues described howi helped ward off disease in cotton (and other plants).

ilicon is taken up as silicic acid by the root system of higherplants and moves upwards in the transpiration stream to sites ofstrong evapotranspiration where it is transformed into insolublepolymers, inda wrote. Once polymerised, silicic acid is no longeravailable as a source of silicon for any other part of the plant.

mproved resistance to disease and pathogenic fungal attackdue to i applications has been reported for a number of crops.s most parasitic fungi penetrate the host by boring throughthe epidermal cell wall, i in these walls may act as a mechanicalbarrier.

n addition to decreased susceptibility to fungal pathogens(and insects), the benecial effects of adequate i includereduced manganese and iron toxicity, reduced salinity and waterstress, protection of leaves from ultraviolet radiation damage andincreased growth in some plants, inda added.

More information: Austin Smith 07 5446 6602 or see www.nutrifert.com.au n

MarchApril 2011 Australian Grain 35

Silicons key role in plant growthn By Austin Smith, Nutrifert

Paddock demonstrations in 2008 at Allora on Qlds DarlingDowns, showed greatly enhanced wheat root developmentin those plants where seed was coated with a silica product

(Amorsil Max) at 20 per cent.

AT A GLANCE

n Silicon ertilisers with high PAS content have many potential

benefts and sufcient Si supply aids healthy growth andproductive development.

n Applied silicon ertilisers interact positively with appliedmajor and trace elements improving their agronomicperormance and efciency.

n Silicon ertilisers also enhance the plants ability to resist ortolerate biotic stress such as attack o insect pests and ungalattacks.

n Silicon ertilisers can help alleviate abiotic stresses due toacidity, salinity and toxicities.

n Silicon ertilisers can help reduce water loss andtranspiration.