1 (6/2016)

Boron is an essential nutrient for plant growth and development. It is a critical building block for cell growth, aiding in the transfer of sugars and nutrients from roots to leaves and reproductive organs. It also increases pollen tube elongation and fruit development.

In coffee cultivation, boron is the most common micronutrient deficiency. . Boron’s primary role in coffee is to act as a key component in a number of vital processes such as cell division, root development, cell wall formation, and calcium uptake.

Symptoms of Boron DeficiencyBoron deficiency causes the death of the terminal growing point. The later development of secondary branches (sometimes as many as seven at the same node) below the dead terminal bud gives the typical fan-like effect. In severe cases the secondary branches quickly die resulting in the typical dieback of terminal sections of the new shoots. Such dieback can be distinguished from that caused by disease by the associated leaf symptoms, and if necessary, by analysis of young leaves.

The leaves are typically misshapen and reduced in size. They are often narrow and twisted with irregular edges and have a leathery texture. The internodes are short, leaf tips may fail to develop properly, and the apical portion may then characteristically turn a pale olive-green color. In contrast, the basal portion

of the leaf remains a deep dark green. It has been suggested that this apical chlorosis is due to a local calcium deficiency which may be the result of B deficiency reducing calcium translocation.

Defoliation can occur. The underside of the midrib of both chlorotic and otherwise healthy older leaves may become suberized.

Production will be seriously reduced because of poor fruit formation. In nutrient solution studies, it has been demonstrated that B deficiency does not seem to affect flowering but that in contrast fruiting is markedly reduced. In controlled experiments, no fruit was produced even though flowering was regular. This is an accord with work demonstrating that coffee shows a peak demand for B (and for calcium) just after flowering and when the formed cherry is developing.

Terminal dieback and the development of crinkled leaves towards the end of a dry period and at the start of the rainy season (due to reduced B absorption from the dry upper soil layers) are often the first signs that coffee is suffering from B deficiency.

Symptoms are also particularly noticeable at flowering and after liming due to the reduced availability of soil boron. Boron is mainly used on coffee to prevent the occurrence of the transient deficiency symptoms rather than to correct severe deficiencies which result in considerable branch dieback.

Brazil Coffee StudyPart of Rio Tinto

2 (6/2016)

Part of Rio Tinto

Minerals that make a differencewww.borax.com

Coffee Field TrialsUS Borax conducted coffee trials near Espìrito Santo do Pinhal, São Paulo state Brazil during the 2013/2014 and 2014/2015 growing seasons. The soil in the area of the test was found to be low in boron, but not deficient (0.5ppm B). In this test, US Borax’s product Granubor 2 was compared to locally sourced granular ulexite for soil application at a dose of 1.5kg B (10.5kg product)/ ha. Both products claim similar boron content – Granubor 2 contains 14.3%

B and granular ulexite contains 10% B. The results from the trial showed that Granubor 2 had superior performance over both control and granular ulexite, winning at highest yield and highest quality.

4.96

6.39

7.89

5.315.81

n Control n Ulexite n Granubor 2 n Boric Acid n Disodium Octaborate

Figure 1. Yield (average of 2 years)

Fruit/plant (L/plant) 1.5 kg B/ha

Figure 2. Yield (average of 2 years)

Yield (t/ha) 1.5 kg B/ha

n Control n Ulexite n Granubor 2 n Boric Acid n Disodium Octaborate

2.12

2.8

3.79

2.332.66

32.5 35.022.5

67.5 65.0 77.5

Control Ulexite Granubor 2 (1.5kg/ha) (1.5kg/ha)

Figure 3. Quality from 1st year

Qualityn % Floating

n % Green/Mature

100.00

90.0

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

0.0

Suggested rates of application

Application by soil Granubor 2

15 – 30 g/plant

Field studies conducted by Adubai www.adubai.com.br