Response to divergent mass selection for plant architecture and earliness and its effect on seed yield in Dimorphotheca pluvialis

Abstract

Seeds of Dimorphotheca pluvialis contain oil with a unique fatty acid composition, making it a potential raw material for several industrial applications. So far, the species has not been used in arable farming. The currently available plant populations show considerable variation for morphological and agronomic traits. Divergent mass selection for plant architecture and earliness was performed, aiming at the creation of more uniform populations and subsequently the determination of the plant ideotype. Three cycles of combined selection for plant architecture and earliness resulted in a significant response for both traits in both directions, even at a low selection pressure. Selection for early flowering or procumbent plant architecture showed a better response and a higher realised heritability than selection for late flowering or upright plant architecture. At low plant densities (4 plants/m 2), as used during selection, differences in plant architecture between procumbent and upright selections were clearly visible. However, at densities used in cultivation practice (50 plants/m 2), the crops produced by the two plant types looked remarkably similar; between the plots no clear differences in plant architecture could be seen. The different plant architecture selections showed similar flowering development and seed yield, and therefore no ideal plant architecture type could be defined with regard to breeding for increased seed yield. Earliness, however, had a significant effect on seed yield; early flowering selections showed the highest yields. Since genotype by year interactions could not be determined, no firm conclusions on the ideotype with regard to earliness should be drawn. Nevertheless, (very) late flowering selections in general are undesired in the Netherlands because of an increased risk of experiencing unfavourable weather conditions during flowering and seed set.