Genetic Variation of Thermotolerance during Reproduction in Spring Canola (Brassica napus L.).

Genetic variation of thermotolerance during reproduction in spring canola (Brassica napus L.)

C.B. Koscielny, R.W. Duncan, J.D. Patel

Abstract

Heat stress can limit the yield and geographical distribution of Brassica napus L. (spring canola) grown in western Canada. Heat is especially problematic in western Canada because the most sensitive growth stage in spring canola (floral development/reproduction) often occurs during the highest temperatures of the growing season. Thermotolerance has been studied within Brassica species and genetic improvements have been achieved in other species such as Cicer arietum L., Triticum aestivum L., Oryza sativa L., and Solanum lycopersicum L; however, to date there have been few studies on the variation within spring canola. The simplest and quickest method of improving a trait is to utilize the existing variation within elite germplasm, if sufficient variation exists. The objective of this research is to determine if sufficient genetic variation exists within elite spring canola germplasm to enable selection for increased thermotolerance during the reproductive stage. Experiments have been setup in controlled environments and multiple field locations to evaluate B. napus genotypes under multiple temperature regimes. The elite B. napus genotypes were evaluated for flower number, pod number, biomass, maturity, seed yield, thousand kernel weight, floral bud metabolite content and carbon isotope ratios. Preliminary results suggest the genetic variation of thermotolerance within this elite set of spring canola inbreds is sufficient to allow selection for improvement of this trait. With this information, breeders will be able to apply selection pressure for thermotolerance and make genetic improvements quickly by staying within the primary gene pool. If thermotolerance is increased for spring canola it will not only protect the potential seed yield, but will also increase the economically viable land base in which spring canola can be grown.   The results from growth chamber and field experiments will be discussed.