Cheatgrass inhibits wild potato (Solanum jamesii) tuber sprouts

Authors: Bamberg, John; KAZMIERCZAK, TIMOTHY; COLQUHOUN, JED - UNIVERSITY OF WISCONSIN; DEL RIO, ALFONSO - UNIVERSITY OF WISCONSIN

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2022
Publication Date: 1/10/2023
Citation: Bamberg, J.B., Kazmierczak, T.M., Colquhoun, J., Del Rio, A. 2023. Cheatgrass inhibits wild potato (Solanum jamesii) tuber sprouts. American Journal of Potato Research. https://doi.org/10.1007/s12230-022-09903-1.
DOI: https://doi.org/10.1007/s12230-022-09903-1

Interpretive Summary: The potato crop is the world's most important vegetable, but could benefit from genetic improvement through breeding. Fortunately, there are many wild and cultivated potato relatives rich in useful traits. These are collected, preserved, evaluated and distributed from the U.S. Potato Genebank at Sturgeon Bay, Wisconsin. One such wild species, Solanum jamesii, grows naturally in the USA, and serves as a handy model of how natural factors impact genetic resources in the wild. One such factor is weeds. We obtained seeds of Bromus tectorum (cheatgrass) and planted sprouted jamesii tubers in trays of cheatgrass in the greenhouse. We also tested soil with dried cheatgrass roots and straw. Live cheatgrass and dried straw both inhibited the growth of the wild potato sprouts. We assume that weeds compete with wild potato for moisture and soil nutrients, but this experiment demonstrates that cheatgrass can also inhibit wild potato even in optimal conditions. It highlights the need to assess sites where natural potato populations are threatened, and to collect and secure samples of their genetics in the genebank before they are lost.

Technical Abstract: Cheatgrass (Bromus tectorum) in a non-native grass that has invaded the natural range of the two wild potato species in the USA. We sought to detect evidence that it suppresses Solanum jamesii (jam). We grew flats of 12 cheatgrass populations and dried and stored the straw and the media containing the roots. In the following year, we again prepared flats of actively growing grass as well as flats with plain potting medium as control. One sprouted tuber of each of 35 jam populations was planted in a flats of each of the 12 cheatgrass populations for each treatment: Control, Grass, Straw, and Roots. Percent shoots emerged in Root media treatment was not significantly different from Control, each at about 93%, but Grass (70%) and Straw (80%) were significantly lower than Control. The 12 cheatgrass populations inhibited jam tuber shoots compared to Control differently, as Grass (8% to 43% reduction) and as Straw (0% to 33% reduction). Subjective scores of the vigor of cheatgrass and emerged jam stands indicated that a more vigorous stand of cheatgrass is associated with less vigorous jam shoots. It appears that cheatgrass can significantly inhibit jam shoots from sprouted tubers even when growing in optimal conditions.