boron dyanamics

1. WELCOME
M. Tejaswini
PAMM 0024
Senior M.Sc. (Agri.)
Dep. of SS & AC
27 August 2022 Department of SS&AC 1
2nd seminar

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Importance of boron
in plant nutrition

3. INTRODUCTION
FUNCTIONS OFBORON IN PLANTS
BORON DEFICIENCY
BORON TOXICITY
MANAGEMENT PRACTICES
ROLE BORON IN HUMAN NUTRITION
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FLOW OF THE SEMINAR

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In 1808 - Boron was discovered
by Joseph-Louis Gay-Lussac &
Louis-Jacques Thenard
Independently by Sir
Humphry Davy, an English
chemist in 1808
One of the 8th essential micronutrient required for normal
growth of most plants in very small quantity & essentiality of
boron in plant nutrition was demonstrated in USA by Katherine
Warrington in 1923.

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6. • Boron is electron-deficient, possessing a vacant p-orbital
• Boron family - group 13 & 2nd period
• In this group, five elements namely Boron, Aluminium, Gallium, Indium
and Thallium are included, of which only boron is a metalloid.
• Boron existing as a dark brown to black amorphous powder or
extremely hard black silver-gray, brittle, lustrous metallic crystalline.
• . Boron does not occur in nature as a pure element and so it is always
associated with oxygen in nature. Boron ion is small (r= 0.11Å) and
can occur in both triangular and tetrahedral coordination to oxygen.
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7. Total boron content in Indian soils
Total B content in diversified types of Indian soils varied from
2.8-630 mg kg-1.
Soils in arid and semiarid tropical regions had the highest
contents of boron and the content varied with parent materials.
Total B content in calcareous soils of India reportedly as high
as 83 mg kg-1, while that of the same content in coarse textured
leached soils showed lower B contents
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Prasad et al., 2014

8. Available B content in soils of India ranged from 0.04 to 7.40 mg
kg-1 with a mean value of 1.7 mg kg-1
Out of about 40,000 soil samples. About 4.0, 19.2, 21.5, 12.1, 11.4
and 31.7% area shows acute, deficient, latent deficient, adequate,
high and very high in available B content in Indian soils
respectively.
In general, the magnitude of B deficiency in soils of North-East and
Eastern India is relatively higher.
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FAO, 2018

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Boron content in southern Karnataka
Narayana et al., 2013

10. Total boron concentrations in major rock types
Rock type Boron (mg kg-1 )
Igneous Basic: Gabbro, Basalt 5-20
Intermediate: Diorite 9-25
Acid: Granite, Rhyolite 10-30
Metamorphic Gneiss 10-30
Sedimentary Shale 120-130
Sandstone 30
Limestone & dolomite 20-30
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11. Mineral sources of boron
Ulexite (NaCaB5O9.8H2O) Borax (Na2B4O5(OH)4.8H2O) Colemanite (Na2B4O5(OH)4.8H2O)
Kernite (Na2B4O6(OH)2.3H2O). Tourmaline Kotoite
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12. Forms
of boron
in soil
Soil
Solution
Adsorbed Organically
bound
Residual
B
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Largest pool

13. Factors affecting Boron availability
Soil pH
Soil texture
Soil moisture
Temperature
Boron absorbing surfaces in soils
Oxides
Clay minerals:- Kaolinite < Montmorillonite <
Illite
Calcium carbonate
Organic matter
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Boron adsorption on a surface
and a subsurface sample of an
arid zone soil as a function of pH.
Boron uptake by alfalfa
(Medicago sativa) as a function
of water soluble B for two soil
textures

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Boron adsorption on an arid
zone soil as a function of
temperature.
Boron adsorption on clay
minerals as a function of pH

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Boron adsorption on a reference
calcite as a function of pH
Boron adsorption on a humic
acid extracted from soil
Berg et al., 2002

17.  There are three pathways
1. Passive diffusion through plasma membrane
2. Facilitated transport via channel proteins
Nodulin 26-like intrinsic proteins [NIPs]
(Root epidermis, cortical & endodermal cells)
3. High affinity active transport
Borate transporters [BOR]
(Pericycle cell)
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Mechanism of B uptake

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Mechanism of Boron uptake & transport in plants
H3BO3 , H2BO3
-
Shireen et al., 2018

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20. • Typical component of cell wall include cellulose, non-
cellulose, pectin polysaccharides, proteins, phenolic
compounds and water.
• Rhamnogalacturonan II (RGII) is a pectin polysaccharide
where B cross-links two RGII monomers by a borate bridge
and thus provides stability to the cell-wall matrix.
• Limited B supply reduces RGII dimer formation, resulting in
abnormal cell wall formation.
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Ishii et al., 2001

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22. Structural
integrity
Ion flux
P.M bound
enzymes
Cell
division
&amp;
elongation
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23. • Boron plays an important role in both structural and functional
integrity of plasma membranes.
• In B-deficient plants, plasma membranes are highly leaky and
lose their functional integrity
• Alterations in ion fluxes i.e. H+ , K+ , Rb+ , PO4
-3 , and Ca+2 is
associated with B deficiency
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K transport
Opening & closing of stomata
Photosynthesis &chlorophyll
formation

25. • Boron supply enhances the activity of membrane bound
ATPase
Hyperpolarization
Boron
ATPase
K+ ions uptake
(Opening of stomata)
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Ahmad et al., 2009

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Anther formation
Pollen germination & pollen
tube growth
Flower & Fruit production

27. Effect of different concentrations of B on number of flower Cluster Plant-1 of
Rio Grand and Rio Figue cultivars of Tomato
B (kg/ha) Rio Grand Rio Figue Mean
Control 17.13 16.37 16.75 c
0.5 23.69 22.24 22.97 b
1.0 25.83 23.16 24.50 b
2.0 30.70 24.77 27.73 a
3.0 24.17 26.43 25.30 ab
5.0 25.35 23.16 24.25 b
Mean 24.48 22.69 -
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28. B (kg/ha) Rio Grand Rio Figue Mean
Control 41.64 d 37.91 c 39.77 c
0.5 54.11 b 51.18 bc 52.64 ab
1.0 49.63 c 52.14 bc 50.88 b
2.0 59.34 a 52.32 bc 55.83 a
3.0 51.52 c 49.57 c 50.54 b
5.0 50.54 c 50.01 c 50.27 b
Mean 51.13 48.85 -
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Effect of different concentrations of B on fruit set percentage of
Rio Grand and Rio Figue cultivars of Tomato
Naz et al., 2012

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Wang et al., 2003
Dose-dependent effects of boron on Picea meyeri
pollen germination.

30. Effect of different concentration of B on growth parameters in
Brinjal
Treaments
B (ppm)
No. of flower
buds / plant
No. of flower /
cluster
Total number
of flower
clusters/plant
Total number
of
flowers/plant
50 34.33 b 3.3 b 11.67 b 25.00 bc
100 38.67 a b 3.3 b 13.0 ab 33.67 b
150 47.00 a 5.3 a 16.33 a 43.67 c
Control 27.67 b 2.2 b 11.00 b 19.67 c
F-test 0.0218 0.0152 0.0437 0.0018
LSD 11.059 1.66 3.72 9.367
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Kumuthini et al., 2014

31. Ion uptake
Nitrogen
fixation
Root hair
formation
Lateral root
development
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Weeks after inoculation
Nodule weight in pea root growth with sufficient and
deficient boron supply
Dalton et al., 2009

33. • Uptake rate of phosphate was decreased by B
deficiency, and the reduction in phosphate uptake was
rapidly restored by resupply of B to deficient plant
for 1 h
Faba bean Maize
+B -B +B -B
No boron 112 52 116 66
10-5 M B 152 108 190 171
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Phosphate uptake (n mol g-1 h-1)
Pollard et al., 2005

34. B
Phenolic
metabolism
Nucleic
acid
&amp;
IAA
metabolism
Plant
respiration
Sugars
transport
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Pentose P
pathway
6-phosphogluconate dehydrogenase
6-phosphogluconate

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Phenol Metabolism

37. Plant age
(days)
Deficiency
symptoms
Leaf extract Detached leaves
+B
(50µM)
-B
(0.05µM)
+B
(50µM)
-B
(0.05µM)
4 Absent 100 106 100 102
6 Mild 100 442 100 900
8 Severe 100 475 100 1466
10 Very
severe
100 542 100 2200
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Activity of polyphenol oxidase in sunflower leaves
(1mM DOPA as a substrate)
Shelp et al., 2001

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Spectrophotometric analysis dipicting IAA contents of
Triticum durum viz Gediz seedlings grown in different media
containing varying boron levels
Guven et al., 2003

39. BoronDeficiency
 With <0.5 ppm usually being deficient
 Deficiency symptoms first appear in young growing
parts of the plant
 Boron deficiency symptoms appears in both leaf and
fruit.
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40. visual symptoms
 The main leaf symptoms are distortion of new leaves
and Young fruit can die or abort and Leaves may be
thickened, curled, and brittle. Stems may also become
cracked.
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B deficiency in potato

41. • The terminal growth shows resetting, die back,
discolouration, necrosis of tips and leaf margins,
elongate, but such symptoms varied with nature and
type of individual crop.
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Brown heart of cauliflower Chaffy grains in wheat

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Chicken and hen
disease in grapes
Hallow stem in broccoli
 Carrot, Coffee, Cotton, Grapes, Groundnut, Mustard, Oil
palm, Sugar beet, sunflower, Turnip.

43. • Abnormal cell wall formation
• Altered membrane potential &amp; reduced proton
pumping
• Alters plasma membrane permeability for ions &amp;
solutes
• Increased O2supply in root nodules
• Root growth will be decreased
Effect on cellular functions
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44. Boron Toxicity
 >1.5 ppm usually being toxic.
 Boron toxicity can arise under excessive
application of boron through fertilizers.
 Under low rainfall conditions.
 In arid & semi-arid regions with high boron
groundwater.
 Peach, Beans, grapes & Fig
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45. Toxicity symptoms
• Leaf margins may develop a red or yellow colour,
which may lead to necrosis, or death of plant tissue.
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Malus spp Grapevine

46.  Plant may experience stunted growth, bushy with few
small thinly branched leaves supporting small
chlorotic and curled up leaflets
 Boron toxicity symptoms occur in the marginal
region of mature leaves, and these portions become
chlorotic or necrotic
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Brassica rapa var. chinensis Boron toxicity in rice

47. Toxicity effect on cellular functions
 Reduced cell division
 Lower leaf chlorophyll content & photosynthetic rate
 Decreased lignin & suberin levels
 Reduced growth of shoots & roots
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Yermiyahu et al., 2007

49. Interactions of boron
with other nutrients
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50. Nutrients Interaction
B × N +Ve in plant
B × K +Ve at B high concentration in soil
-Ve at B low concentration in soil
B × Ca -Ve in alkaline soil and an over-liming
+Ve when microbial activity increases
B × S +Ve
B × P +Ve
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Kumar et al., 2018

51. Occurrence of controlled atmosphere (CA) conditions-related
disorders in boron and calcium treated ‘conference’ pears during a 5-
month CA-storage period at 5 % CO2 + 2 % O2 at -0.5°C.
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Effect of boron and boron + calcium application on ethylene
production of ‘conference’ pears stored for 5 months under CA
conditions (5 % CO2 + 2 % O2 at -0.5°C)
Xuan et al., 2003

53. Effects of the B/Ca2+ ratio on nodulation (B) of pea roots 3 weeks post
inoculation with Rhizobium
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Bolanos et al., 2003

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Hosseini et al., 2007

56. • Boron deficiency is identified by
I. Hot water method for soil available B estimation
(0.5-1.5ppm).
II. Plant tissue test (4-74 ppm)
Application methods
i. Soil application
ii. Foliar application
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Management of boron deficiency

57. Fertilizer sources of B
Boron fertilizer Nutrient content (%) Chemical formula
Borox 11 Na2B4O7. 10H2O
Boric acid 17 H3BO3
Colemanite (Portabor) 10-16 Ca2B6O11. 5H2O
Solubor 20-21 Na2B4O7.5H2O +
Na2B10O16. 10H2O
Boron frits 2 – 6 Complex borosilicates
Sodium tetraborate
(Fertilizer Borate-48,
Agribol, Fertibor)
15.2 Na2B4O7. 5H2O
Granubor 14.3 Na2B4O7. 5H2O
Boronated SSP 0.18 -
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B Fertilizer applied
to soil Soil solution
Bounded Boron
Organically bound B
Leaching
Plant
uptake

59. Effect of foliar B application to cotton during anthesis on yield
parameters in two locations (Larissa and Serres)
Treatments No. of bolls
per plant
No of bolls per
m2
Lint yield
(kg/ha)
Seed yield
(kg/ha)
Larissa
0 5.62 a 84.37 a 1135.98 a 1926.5 a
400 6.25 b 93.75 a 1980.7 b 2900.3 b
800 6.56 b 98.44 b 1870.5 b 2535.4 b
1200 7.18 c 107.81 c 2050.8 b 2700.5 b
Serres
0 4.12 a 61.87 a 1282.2 a 1747.8 a
400 5.45 b 81.75 b 2067.9 b 2049.5 b
800 6.35 b 95.25 b 1949.3 b 2040.7 b
1200 5.75 b 86.2 b 2052.3 b 2171.1 b
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Dordas et al., 2007

60. Importance of boron in humans
 In human nutrition BORON is classified in the category of
ossible essential element.
 Boron intakes above 1 mg day-1 could help people ‘‘live longer
and better.’’
 The mean intake of B from dietary supplement for
 Children: 0.269 mg day-1
 Adolescent : 0.160 mg day-1
 Males : 0.174 mg day-1
 Females : 0.178 mg day-1
 Pregnant and lactating women: 0.148 mg day-1
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Role of boron in humans

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