Feasibility of boron fertilization for yield, seed quality and B uptake of canola in northeastern Saskatchewan
Authors: Malhi S. S. , Raza M. , Schoenau J. J. , Mermut A. R. , Kutcher R. , Johnston A. M. , Gill K. S. 
Published: April 2011

(Brassica napus L . and B. rapa L.) grown on the sandy soils of northeastern Saskatchewan has been observed to exhibit symptoms similar to B deficiency, and soil testing laboratories often recommend B fertilization on these soils. The objective of the present study was to determine if yield, seed quality and diseases of canola are related to different rates, times and methods of B fertilization on some northeastern Saskatchewan soils (Gray Luvisol) expected to be B deficient. Two growth chamber and seven field experiments were conducted in 1997, 1998, 1999 and 2000. In the field experiments, the treatments included application of B fertilizers as broadcast followed by incorporation (1 to 4 kg B ha-1) prior to seeding, seedrow placement at seeding (0.5 to 2 kg B ha-1) and foliar spray at 10–20% bloom stage (0.25 and 0.50 kg B ha-1) plus a zero B control treatment. In the growth chamber experiments, rates of 1 to 3 mg B kg-1 soil were tested. In the field experiments, seed and straw yields tended to increase in very few of the treatments, with significant increases from incorporated B fertilization at one site for seed and at three sites for straw. The protein content in the seed was significantly increased by B fertilization at one site, while oil content in the seed was not influenced by B fertilization in any field experiment. The B fertilization treatments either increased or tended to increase the B concentration and uptake of B in seed and straw in most cases, with significant contrasts for control vs. incorporated B and seedrow B methods of applications in many cases. The increase in B concentration and uptake of B was usually greater in straw than in seed. Among the methods of B application, the effectiveness of B application could be considered as incorporated B > seedrow B > foliar B. Averaged across the sites and two treatments for each application method for example, B uptake in seed increased by 6.7, 3.8 and 1.0 g ha-1 with incorporated, seedrow and foliar B treatments, respectively. Corresponding methods showed an increase of B uptake in straw by 46, 33 and 23 g ha-1. Disease levels were low for sclerotinia stem rot (Sclerotinia sclerotorum) and low to moderate for blackleg (Leptosphaeria maculans) and alternaria pod spot (Alternaria brassica and A. raphani), and B fertilizer treatments had no impact on the amount or severity of infection for these diseases. In the growth chamber experiments, B fertilization tended to increase the yield of seed and straw (up to 13%) in both soils, with significant contrasts for 0 k g B ha-1 vs. 1, 2 and 3 kg B ha-1 in many cases. In conclusion, the findings of this study suggest that canola rarely responds to B fertilization in field conditions on soils suspected to be B deficient, but canola response to B was influenced by the method of B application. Key words: Boron concentration and uptake, boron fertilizer, canola (Brassica napus L. and Brassica rapa L.), oil and proteincontent, yield