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Jaworski, C.A. and S.C. Phatak. 1993. Canola seed yield in relation to harvest methods. p. 300-301. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Canola Seed Yield in Relation to Harvest Methods

Casimir A. Jaworski and Sharad C. Phatak


  1. METHODOLOGY
  2. RESULTS
  3. REFERENCES
  4. Table 1
  5. Table 2

Rapeseed/canola (Brassica napus L. and B. campestris L.) recently moved up to the world's third most important edible oil source after soybean and palm, and has the largest annual growth rate of the 10 major edible oils (Downey 1990). Canola consumption is rapidly increasing in the United States due to its lowest saturated oil (6%) of all vegetable and animal oils, the granting of GRAS (Generally Regarded As Safe) status to low erucic acid rapeseed (LEAR) oil by the Food and Drug Administration (FDA) in 1985, and allowance of the term canola on food labels by FDA in late 1988 (Neshem 1990). Most of the canola presently consumed domestically is imported.

Available area potential for double cropping with traditional summer row crops, adequate rainfall and mild winters are factors which make the southeastern United States very promising for canola production (Raymer and Thomas 1990). However, the natural dehiscent process, indeterminate growth, long period of seed maturity, and variable weather conditions such as wind and rain are some factors which can lead to large seed losses (Hall 1990; Ogilvy 1989). Seed shattering and seed loss at harvest become even more critical since late spring cultivars seeded as winter annuals in south Georgia mature earlier and produce larger yields than winter cultivars; however, these spring cultivars are more subject to seed shattering than the winter cultivars. The objective of this study was to determine if swathing canola improves seed recovery as compared to direct combining.

METHODOLOGY

Four canola harvest tests were conducted in 1990 with 'Legend' and 'Global', spring cultivars (Table 1 and 2). Seeding for tests 1 and 2 was Oct. 12, 1989 and for tests 3 and 4 on Oct. 31, 1989. Test 1 was carried out with 'Legend' and treatments were direct harvest and swathed for 14 and 21 days. Test 2 was with 'Global' and treatments were direct harvest and swathed for 7, 14, and 21 days. Test 3 was with 'Legend' and treatments were direct harvest and swathed for 6, 12, and 19 days. Test 4 was with 'Global' and treatments were direct harvest and swathed for 7, 12, and 18 days. Swathing was done when 30% of the seeds changed from green color (Apr. 11, Apr. 25, May 2, and May 3, 1990 in tests 1, 2, 3, and 4, respectively). Clipping was carried out with a gasoline powered ornamental hedger and thrashing with a stationary harvester. The 1990 canola harvest season was unusually dry with only significant rainfall of 0.38, 0.28, and 0.61 cm on Apr. 28, May 9, and May 10, respectively.

RESULTS

'Legend' seed yields were not significantly different between harvest methods and averaged 2,173 and 1,756 kg/ha, respectively, for tests 1 and 3 (Table 1). 'Global' seed yields for direct harvest and swathed for 7 days were 2,278 and 2,778 kg/ha in test 2 and 1,650 and 2,165 kg/ha in test 4, respectively (Table 2). Harvesting after 7 days of swathed was 7 to 9 days earlier than direct harvest.

Direct harvesting of 'Global' had lower seed yields when compared to swath treatments. Seed yields from direct harvest and swathing treatments were however similar for 'Legend'. The 7 to 9 day earlier harvest for a 7 day swathing as compared to direct harvest would give more time for establishing a traditional summer row crop in a double-cropping system.

REFERENCES


Table 1. Seed yield of 'Legend' canola as affected by harvest system (test 1 and 3).

Test 1 Test 3
Harvest system Harvest date Seed yield (kg/ha) Harvest date Seed yield (kg/ha)
Direct harvest May 3 2,081z May 17 1,580z
Swathed 6 days --- --- May 8 1,835
Swathed 12 days --- --- May 14 1,820
Swathed 14 days April 25 2,285 --- ---
Swathed 19 days --- --- May 21 1,790
Swathed 21 days May 2 2,154 --- ---
zEach value represents mean of six and five observations in test 1 and 3, respectively. Treatment means are not significantly different.


Table 2. Seed yield of 'Global' canola as affected by harvest system (test 2 and 4).

Test 2 Test 4
Harvest system Harvest date Seed yield (kg/ha) Harvest date Seed yield (kg/ha)
Direct harvest May 11 2,278bz May 17 1,650bz
Swathed 7 days May 2 2,778a May 10 2,165a
Swathed 12 days --- --- May 15 2,056a
Swathed 14 days May 9 2,761a --- ---
Swathed 18 days --- --- May 21 1,896a
Swathed 21 days May 16 2,749a --- ---
zMean separation within column by Duncan's multiple range test, P [[threesuperior]] 0.05. Each value represents mean of six and five observations in test 2 and 4, respectively.


Last update April 15, 1997 aw