Post flowering temperature as main factor regulating canola yield and oil content.

VILARIÑO M. P.; RONDANINI D.P.; MIRALLES D. J.; AGUIRREZABAL L.A.N.

Nyon

Congreso; GCIRC Technical meeting 2013; 2013

International Consultative Group of Research on Rapeseed

Canola (Brassica napus L.) is one of the most important edible oils, but even though Argentina has a big potential cropping area, the crop has not been yet fully adopted. Mean harvested area for the five last years was about 12000 has, with an increase in 2008 of almost 40000 has; canola average yields in Argentina are between 1250 and 1900 kg. ha-1. Among the reasons for the scarce crop adoption is the lack of accurate studies on genotypic adaptation to different environments, which leads to unpredictable and low yields. A research goal is to assess main factors influencing crop yield so as to elaborate adequate crop management strategies. To fulfil this goal, an experiment was carried out using 4 spring genotypes: 2 short, Hyola 61 (Hy) and BioAureo 2486 (Bi) and 2 intermediate cycle genotypes, Jura (Ju) and Gladiator (Gl),  and 2 winter genotypes, Barrel (Ba) and Gospel (Go). They were sown in 4 dates: 04/30 and 07/01, 2008 and  04/15 and 06/09, 2009 (FS1 and FS2, respectively within each year) in 6-rowed, 3m long plots, with 3 replications, at the Faculty of Agronomy (UBA), Buenos Aires (34º35’S, 58º29’O) experimental field. Phenology was recorded and intercepted radiation was measured throughout the crop cycle, and at harvest maturity plants in 0.5 m-2 were harvested for yield and yield components determination. Grains were analyzed for oil content (Soxhlet) and composition and protein concentration (Kjeldhal). Temperature data were obtained from a meteorological station nearby the experimental site. Results showed a great difference between years, being yields 78% higher in 2008 (mean extreme values were 4561 kg.ha-1 for Bi FS1, 2008 and 422 for Go in FS2, 2009). Significant differences in grain yields were also found among genotypes, all spring cultivars had higher yields than winter cultivars, and between sowing dates, FS1 yielded more than FS2. Late sowings represented a shortening of cycle length (about 20% less) for all cultivars. Sowing delays involved also an exposure to higher post flowering temperatures, mean temperatures were between 14.5 to 20.8 ºC, responsible for a decrease in grain number, a yield component highly associated to yield, 2009 experiment showed a mean drop of 7000 grains per m-2 for each 1ºC increased (r2= 0.43). Temperature also affected grain weight and oil concentration (1% drop for each 1ºC increased), resulting in both less grain and oil yield per area. We conclude than it is possible to get good yield and quality in our latitude with early sowings of spring cultivars that allow avoiding exposition to high post flowering temperatures.