Tradeoffs between productivity and nitrogen conservation in wild and domesticated plants of the perennial crop Physaria (Brassicaceae)

Abstract

Domestication of desert-adapted perennials has been proposed as an alternative to increase cropping intensity in low input environments. However, selection for high yield in perennial crops provokes indirect changes in plant resource use. These changes might alter how nitrogen is acquired, allocated, used and stored, thus affecting plant longevity and yield stability. Using the perennial forb Physaria as a model, we compared the pattern of N allocation, use and conservation of high-yield accessions (Y), and stable yield accessions (S), with their wild counterpart (W). We found a negative relationship between seed yield and N conservation capacity and their associated traits. The shift of strategy provoked by high yield selection implies changes in N allocation and a decrease in nitrogen use efficiency and conservation capacity at plant- and leaf-level. S accessions also increase allocation to seeds, although they kept the N use and conservation traits of their wild counterparts, remaining in an intermediate position between the Y and W accessions profiles. The shift of strategy provoked by high yield selection implies a decrease in nitrogen use efficiency and conservation capacity that may be behind the loss of longevity and yield on subsequent years. Wild and stable accessions were more conservative and show traits that promote nitrogen conservation. These are key traits that should not be lost during the selection process if breeders want to achieve the adequate ideotype of perennial crop for arid systems.