Post flowering temperature affects yield and oil content in canola (Brassica napus L.)

VILARIÑO M.P; RONDANINI D; MIRALLES DJ

Bento Goncalves, RS

Congreso; 6th International Crop Science Congress; 2012

International Crop Science Society

Canola (Brassica napus L.) is one of the most important edible oils. Even though Argentina has a big potential cropping area, the crop has not been yet fully adopted. Mean harvested area is about 12000 has, with a mean yield of 1400 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 to elaborate adequate crop management strategies for the Argentinean climatic conditions. The objective of this work was to determine how post flowering temperature affects yield and oil in commercial canola cultivars adapted to Argentina. To fulfil this goal, an irrigated and fertilized field experiment, combining genotypes x sowing date, was carried out in Buenos Aires (34º35?S, 58º29?O). Four spring genotypes: 2 short, Hyola 61 (Hy) and BioAureo 2486 (Bi) and 2 intermediate cycle, Jura (Ju) and Gladiator (Gl), and 2 winter genotypes, Barrel (Ba) and Gospel (Go) were sown in 4 dates: 04/30 and 07/01, 2008 and 04/15 and 06/09, 2009 (SD1 and SD2, respectively within each year) in 6-rowed, 3m long plots, with 3 replicates. Measurements included phenology, intercepted radiation, aerial biomass, grain yield and components, and oil grain content. No interactions among factors were found. Results showed differences between years (p≤0.001), being yields ca. 55% higher in 2008 (mean extreme values were 4561, kg.ha-1 for Bi SD1, 2008 and 422 for Go SD2, 2009). Significant differences in yield were also found among genotypes (p ≤0.001) as all spring cultivars yielded more than winter cultivars. As expected, SD1 yielded more than SD2. A two months delay in the sowing date, shortened the cycle length ca. 20% in all cultivars, and exposed the post flowering period to higher temperatures (mean temperatures: 14 - 20 ºC). Low yield in SD2 was associated with a reduced grain number, as this was the component that better explained variations in yield. During 2009, a rate of reduction of 7000 grains per m-2 for each 1ºC increased (r2= 0.43) was recorded. Temperature also affected grain weight and oil concentration (1% drop in oil for each 1ºC increased), resulting in both less grain and oil yield per area. We conclude that it is possible to obtain good yield and quality in our latitude with early sowings of spring cultivars that allow avoiding exposition to high post flowering temperatures. Further studies on more detailed genotype x environment interactions and breeding for local conditions are needed to match accurately genotypes to such environments.