{Oryza sativa}

Boron and Rice

Boron is essential to rice growth. Enough boron in the soil has the following benefits for rice:

  • Increased pollination and seed set
  • Increased grain filling
  • Reduced chaffiness
  • Reduced bursting when cooking
  • Increased uptake of macronutrients which leads to greater vigor and better use of fertilizer
  • Speeds maturity
  • Increased yield, quality, and income from the crop

When there is not enough boron in the soil, boron deficiency results in reduced pollen viability.

What causes boron deficiency?

Boron deficiency in rice can be caused by one or more of the following:

  • Very little available boron in soil
  • Boron adsorption on organic matter, clay minerals, and sequioxides
  • Reduction in boron mobility due to drought
  • Excessive liming
The critical soil level for occurrence of boron deficiency is 0.5 mg B kg-1.

How common is boron deficiency?

Boron deficiency is not very common in rice, but can occur in the following soils:
  • Highly weathered, acid red soils and sandy rice soils in China
  • Acid soils derived from igneous rocks (as opposed to soils formed from marine sediments)
  • High organic matter status soils in Japan

What does boron deficiency look like?

In rice plants, boron is relatively immobile—it does not move throughout the plant. Because it does not move to new growth, boron deficiency symptoms usually appear first on young leaves. These leaves don’t grow properly—remaining short and narrow with faint white or yellow, rolled leaf tips.
The next emerging leaves will be folded, bent, and almost white. If such leaves open up, a large part of the blade will quickly dry up. Boron deficiency also leads to shorter plant height. When the deficiency is severe, growth stops completely, but new tillers continue to be produced. These tillers will quickly show the same symptoms and remain stunted.
Rice plants may fail to produce panicles if they are affected by boron deficiency at the panicle formation stage. Roots of severely affected plants are stubby, tough and light brown in color.

Prevent and cure boron deficiency

  • Granubor® 2 is an ideal material for dry blends that are applied broadcast preplant or sidedressed.
  • Fertibor® works best in fertilizer suspensions for preplant broadcasts, sidedressing, or band sprayed over the pre-emergent seed row.
  • Solubor® allows the most flexibility for applying boron. It can be dissolved alone in water or in liquid fertilizers and/or pesticides and then applied to the soil or directly onto the foliage.
  • Apply 20 Mule Team® borate fertilizers in soluble forms for rapid treatment of boron deficiency broadcast and incorporated before planting, topdressed, using Fertibor or Granubor or as foliar spray using Solubor during vegetative rice growth.
  • For foliar application, 10g of Solubor in 15L of water is a recommended concentration of the spray solution. Solubor can be mixed with common insecticides or fungicides used in the nursery. Split the boron foliar spray into three or four applications along with the insecticidal or fungicidal spraying rounds.
  • For soil application, broadcast or topdress 4-6kg of Fertibor or Granubor per hectare in one time application before planting or split on twice application half dosage before planting and half dosage at vegetative growth stage.

Soil Application (Suggested rates of application)

  Granubor 2 Fertibor
LBS./ACRE 3-6 3-6
KG/HA 3.38 - 6.75 3.38 - 6.75

Foliar Application (Suggested rates of application)

KG/HA 2.25 - 4.5

Crop study: Rice

China 2013

Hear the key results of a two-year rice trial, conducted by U.S. Borax and the International Rice Research Institute, on the effect of borates on rice quality... Watch video

U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 500 customers with more than 1,700 delivery locations globally. We supply 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles east of Los Angeles.  Learn more about Rio Tinto

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