THE EFFECTS OF BORON ON THE PRODUCTIVITY OF CANOLA

 

Denis Pageau1, Jean Lafond1 and GaŽtan F. Tremblay2

 

1Agriculture and Agri-Food Canada, 1468 St-Cyrille street, Normandin QC, CANADA, G8M 4K3, email: pageaud@em.agr. ca

2Agriculture and Agri-Food Canada, 2560 Hochelaga, Sainte-Foy QC, CANADA, G1V 2J3

 

ABSTRACT

 

Canola is well adapted to the cool and humid climate of Northern Quebec (Canada).† A previous study conducted on barley indicated that some soils of this area are deficient in boron.† Boron is one of the essential micronutrients for plant production and canola has higher B requirements than cereals.† This study was conducted at three sites during three years to assess the effect of B fertilization on yield and oil content.† Boron deficiency has been previously identified on two of the three locations.† Four B rates (0, 0.5, 1.0, and 2.0 kg B ha-1) applied as a foliar spray were evaluated with an additional rate of 5 kg B ha-1 during the last two years.† Treatments were applied to the cultivars Cyclone, Global, and Hyola 401.†† During two years, at the two B deficiency sites, B addition increased B concentration in leaves at flowering, grain yield and oil content.† Generally, at these sites, when no B fertilization was applied, B concentration of canola leaves was lower than 15 mg B kg-1.† At the other site, B leaf concentration at flowering was higher than 30 mg kg‑1 without B addition and B fertilization had no effect on grain yield and oil content.† Low grain yields, poor seedset, red leaves and continuous flowering were symptoms associated with B deficiency.† An application of 1 kg B ha-1 was sufficient to overcome these B deficiency symptoms.† Applications of up to 5 kg B ha-1 did not induce symptoms of toxicity.† This study showed that a B foliar application can increase grain yield and oil content when canola grows on B deficient soils.

 

KEYWORDS: †micronutrient, deficiency, fertilization

 

INTRODUCTION

 

In Northern Quebec (Canada), a previous study indicated that some barley fields presented symptoms of† boron deficiency as low grain yield and high ergot content. In the same area, canola crop was introduced in 1986 and some fields had continuous flowering and low grain yields. These symptoms were also associated with B deficiency.

 

Boron is one of the essential micronutrients for plant production and canola plants have higher B requirements than cereals (Grant and Bailey, 1993). A review on boron roles in plant (Gupta 1993) indicates that B is an important factor in flower fertilization process.† Boron deficient plant may grow normally but seed yield may be severely reduced.† Nuttal et al. (1987) and Porter (1993) indicated that B increased canola grain yield by decreasing the number of sterile florets and improving pod development.

 

The objective of this study was to determine the effect of B fertilization on grain yield and oil content of canola.

 

MATERIALS AND METHODS

 

This study was conducted at three sites in Northern Quebec (Canada) in 1994, 1995 and 1996.† In St-Edmond and St-Prime sites, B deficiency has been previously observed on barley.† In Normandin location, B deficiency has never been observed. The experimental design was a complete randomized block with four repetitions. Each plot was 6-m long and 1.62-m wide.† An area of 3.96 m2 was used to determine grain yields. In 1994, four B rates applied as foliar spray at the rosette stage were evaluated (0, 0.5, 1.0, and 2.0 kg B ha‑1) on three Argentine canola cultivars (Cyclone, Global, and Hyola 401). In 1995, an additional treatment (5.0 kg B ha‑1) was tested. At all sites, nitrogen fertilization was 80 kg N ha-1.† Phosphorus and potassium fertilizations were applied according to soil tests on each site. The seeding rate was 5.0 kg ha‑1 in 1994 and 7.5 kg ha‑1 in 1995 and 1996.† Grain yields, seed oil content, and B concentration of leaves at flowering were determined on each plot.

 

RESULTS AND DISCUSSION

 

Grain yield

 

The effect of B fertilization on grain yield is presented in Table 1.† In 1994, B addition increased canola grain yield in St-Prime only.† At this site, a boron application of 0.5, 1.0 and 2.0 kg ha-1 increased grain yield by 19, 26, and 31%, respectively.† Results from Porter (1993) indicated that a B foliar application of 0.84 kg ha-1 increased grain yield by 6.5%.† In 1995, B application had no significant effect in Normandin, but it had an important effect at the two locations (St-Prime and St-Edmond) where B deficiency has been previously identified.† The year 1995 was very dry and B deficiency symptoms were very apparent.† At those locations, B deficient plant presented red leaves and continuous flowering. Without B fertilization, grain yields were very low; 598 and 63 kg ha-1 at St-Prime and St-Edmond, respectively.† The application of† 1.0 kg B ha-1 was sufficient to eliminate those symptoms and obtain grain yield three to four times larger than controls.† In 1996, B fertilization increased grain yield only in St-Edmond.† At the other locations, B fertilization had no significant effect on grain yield.†

 

These results indicated that boron fertilization increased grain yield two years on three only at the B deficient sites.

 

Table 1:† Effect of B fertilization on grain yield.

 

B fertilization

(kg ha-1)

St-Prime

St-Edmond

Normandin

 

1994

1995

1996

1994

1995

1996

1994

1995

1996

 

grain yield (kg ha-1)

0

1676

598

2763

2073

63

927

2253

1403

2458

0.5

1987

1703

2878

2052

273

2227

2093

1093

2270

1.0

2107

2102

3105

2170

333

2089

2083

1251

2345

2.0

2195

2275

2912

2205

399

2393

2174

1412

2387

5.0

-

2398

3116

-

372

2216

-

1181

2431

Linear effect

Quadratic effect

**

**

**

**

n.s.

n.s.

n.s.

n.s.

**

**

**

**

n.s.

n.s.

n.s.

n.s.

n.s.

n.s.

** Significant at P < 0.01;† n.s.: not significant (P > 0.05).

 

Boron leaf concentration at flowering

 

Boron concentration of canola leaves increased with B fertilization (Table 2).† Without B fertilization, B leaf concentration was approximately 30‑40 mg kg-1 at the site Normandin where B deficiency symptoms were not observed.† However, B concentration was 7‑15 mg kg-1 at the two other locations where B fertilization significantly increased grain yield.

 

Table 2:† Effect of B fertilization on B leaf concentration.

 

B fertilization

(kg ha-1)

St-Prime

St-Edmond

Normandin

 

1994

1995

1996

1994

1995

1996

1994

1995

1996

 

B leaf concentration (mg kg-1)

0

15.0

10.6

14.0

14.9

10.8

7.5

32.3

39.0

34.2

0.5

19.2

16.8

27.4

21.1

19.3

13.6

34.1

42.2

36.5

1.0

22.0

19.0

36.7

23.2

20.6

15.3

35.8

50.4

44.7

2.0

26.8

24.7

70.7

27.1

25.2

20.7

44.7

65.5

51.6

5.0

-

52.1

130.7

-

46.6

34.5

-

91.7

85.4

Linear effect

Quadratic effect

**

**

**

**

**

n.s.

**

**

**

n.s.

**

n.s.

**

**

**

n.s.

**

n.s.

** Significant at P < 0.01;† n.s.: not significant (P > 0.05).

 

Grain oil content

 

Boron fertilization significantly increased grain oil content only when it had a significant effect on grain yield (Table 3).† On average for those sites and years, an application of 1 kg B ha-1 increased the oil content by 12% representing an increment of 4.4 % of the oil content.

 

Table 3:† Effect of B fertilization on oil content.

 

B fertilization

(kg ha-1)

St-Prime

St-Edmond

Normandin

 

1994

1995

1996

1994

1995

1996

1994

1995

1996

 

grain oil content (%)

0

39.4

35.3

43.6

38.9

33.4

40.0

42.1

43.1

40.0

0.5

41.1

41.4

44.1

38.8

38.9

42.7

41.8

42.3

39.6

1.0

41.5

42.6

44.5

38.9

39.3

42.2

41.7

42.6

39.7

2.0

40.8

43.7

44.1

39.4

41.1

42.9

41.7

43.1

39.9

5.0

-

43.8

44.2

-

40.5

42.8

-

42.6

40.6

Linear effect

Quadratic effect

*

**

**

**

n.s.

n.s.

n.s.

n.s.

**

**

**

**

n.s.

n.s.

n.s.

n.s.

n.s.

n.s.

*,** Significant at P < 0.01 and 0.05 respectively;† n.s.: not significant (P > 0.05).

 

CONCLUSION

 

Boron deficiency in canola is associated with low grain yields, red leaves and continuous flowering. This study indicated that boron fertilization can increase canola grain yield and oil content only when plants are boron deficient.† Boron concentration in leaves at flowering for B deficient plants was generally lower than 15 mg B kg-1.† In the present experiment, an application of 1 kg B ha-1 was sufficient to correct B deficiency.

 

REFERENCES

 

Grant C.A. and L. D. Bailey. 1993. Fertility management in canola production.† Can. J. Plant Sci.† 73:651-670.

 

Gupta U.C.† 1993.† Boron and its role in crop production.† CRC Press.† 237 pages.

 

Nuttall, W.F., H. Ukrainetz, J.W.B. Stewart and D.T. Spurr. 1987.† The effect of nitrogen, sulfur and boron on yield and quality of rapeseed (Brassica napus L. and† Brassica campestris L.).† Can. J. Soil Sci.† 67:545-559.

 

Porter P.M.† 1993.† Canola response to boron and nitrogen grown on the southeastern Coastal Plain.† J. Plant Nut.16:2371-2381.