Biomass allocation patterns and reproductive output of four Oenothera L. accessions native to Argentina

Evening primrose (Oenothera spp.) has the potential to become an alternative oilseed crop in Patagonia, Argentina. This paper describes and compares phenology and allocation patterns of four wild accessions of Oenothera grown in a common garden, under non-limiting conditions. Our objective was to identify useful traits to shorten the domestication process. Accessions differed in the duration of the vegetative growth phase, which was negatively correlated to seed production per plant (reproductive output). Fruit set ranged between 70% and 95%, and did not differ among accessions. Differences found in the rate of capsule production did not explain the observed disparity in the number of fruits per plant. Reproductive output was mainly affected by the number of fruits per plant, vegetative biomass, and the proportion between seeds and total biomass (reproductive effort). Individual seed mass did not affect total seed production per plant. Seed-oil content was similar to that of domesticated species of evening primrose, but the content of gamma-linolenic acid was far too low (<2%) in comparison to the minimum acceptable standard necessary for seed commercialization (9%). Oenothera wild accessions are prone to seed losses by shattering. We concluded that short vegetative growth phase and high vegetative biomass would be useful traits for selection in breeding programs. Fruit shattering and low gamma-linolenic acid content are the main drawbacks that should be overcome to facilitate the domestication of one of these wild accessions.