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Abstract
Five cultivars of camelina species (Camelina sativa L.) were grown in the field at two levels of nitrogen (N) under the climate conditions of Hokkaido Island, Japan. N nutrition as well as the genetic difference between cultivars influenced biomass and grain production. Three cultivars responded positively to N application, but not the other two. Increase in grain yield was associated more with grain number than grain size. The plants accommodated the extra grains by increasing pod number. Irrespective of the N level in the soil, α linolenic acid concentration of the grain was very high at 31% of the total fatty acids. In cultivar Calena, lower leaves on the main stem were excised to find the effect of reduced source area on yield. Defoliation of lower leaves did not affect grain yield, indicating that these leaves do not contribute to source capacity of the plant during grain filling. However, removal of all leaves decreased grain yield to 70% relative to the control plant. In contrast to defoliation, shading of the whole panicle consisting of the pod shell and rachis was more effective in reducing grain yield. Shading of the panicle prior to the grain filling period at the levels of 33 and 6% irradiance relative to control decreased grain yield to 39 and 26%, respectively. These results suggested that the pod shell and rachis are more important source organs for photosynthetic carbon supply to grains than the upper leaves, and they can sustain grain filling in exigency. The presence of attributes like extended source area for grain filling and high α-linolenic acid content of leaves is an indicator for successful adaptation of Camelina in the stress-prone environment of Hokkaido Island.
ACKNOWLEDGMENTS
The authors would like to thank the staff at Hokkaido Prefectural Donan Agricultural Experiment Station for technical assistance.
