Silicon (Si) deficiency

Silicon (Si) deficiency effects the development of strong leaves, stems and roots. It also affect the formation of a thick silicated epidermal cell layer, and makes the rice plants susceptible to fungal and bacterial diseases, and insect and mite pests.

Silicon deficiency is not very common in irrigated rice. It occurs in areas with poor soil fertility, and is common in old and degraded paddy soils. It also occurs in organic soils with small mineral Si reserves, and in highly weathered and leached tropical soils in the rainfed lowland and upland areas.

The damage caused by Si deficiency is important throughout the growth cycle of the rice crop.

Severe Si deficiency reduces the number of panicles and the number of filled spikelets per panicle. Si-deficient plants are also particularly susceptible to lodging.

How to identify (symptoms)

• leaves and culms become soft and droopy thus increasing mutual shading
• reduced photosynthetic activity
• lower / reduced grain yield
• increased occurrence of diseases such as blast or brown spot

How to manage

• In the long term, Si deficiency is prevented by not removing the straw from the field following harvest, and recycling rice straw (5−6% Si) and rice husks (10% Si).
• If rice hulls or rice hulls ash are available, recycle them to replenish Si in soil.
• Avoid applying excessive amount of Nitrogen fertilizers
• where possible, apply peat soils at a rate of 1-3 ton /ha regularly to degraded paddy soils