Seed germination dynamics in silverleaf nightshade (Solanum elaeagnifolium Cav.) and implications for effective weed management

Authors: TURNER, NATHAN - Texas Tech University; SANCHEZ, JACOB - Texas Tech University; VAVRA, CODY - Texas Tech University; DHALIWAL, LAKHVIR - Texas Tech University; Emendack, Yves; COLDREN, CADE - Texas Tech University; SHIM, ROSALYN - Texas Tech University

Submitted to: Weed Biology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2021
Publication Date: 7/18/2021
Citation: Turner, N.J., Sanchez, J., Vavra, C., Dhaliwal, L.K., Emendack, Y., Coldren, C., Shim, R.B. 2021. Seed germination dynamics in silverleaf nightshade (Solanum elaeagnifolium Cav.) and implications for effective weed management. Weed Biology and Management. 1-10. https://doi.org/10.1111/wbm.12233.
DOI: https://doi.org/10.1111/wbm.12233

Interpretive Summary: Silverleaf nightshade 'is a deep-rooted, herbaceous perennial that has spread outside of its native range in northeast Mexico and southwest US to become a persistent, noxious weed and invasive species of croplands and rangelands across 21 states in the US and 42 countries worldwide. Management strategies for weed populations have relied heavily on the application of herbicides, although hand-hoeing, crop rotation and biological control agents have been used in conjunction with chemical approaches for weed control. Varying levels of success in managing aboveground populations of of the weed have been achieved by seasonal spot spraying or boom application of the herbicides. Unfortunately, the periodic use of herbicides only offers short-term solutions that minimize the negative impacts of the weed on crop yields within a growing season and does not prevent the resurgence of the weed in the same area year after year. Aside from basic knowledge of the biology of silver weed seeds, understanding the contribution of differing environments conditioning the characteristics of the seeds as they relate to germination potential is equally important in the development of a more integrated system of weed management. Scientists at ARS and Texas Tech University evaluated the effects of different environments on the germination of silver weeds harvested from 3 different ecological collection sites in Texas by looking at morphological and physiological properties of the weed.

Technical Abstract: Solanum elaeagnifolium Cav. is a noxious weed that is native to the southwest US, although its distribution has seen it become an invasive weed on all six of the inhabited continents. Preferring drier weather and being a facultative volunteer in wetter conditions, this weed has become a yearly antagonist to agricultural systems worldwide with the potential to evolve and cause more damage, especially considering its ability to develop herbicide resistance. The development of better strategies to control silverleaf nightshade will require a better understanding of its germination as affected by ecological dynamics. The following study was performed on seed collected from mother plants growing in three distinct ecological environments. Testing involved contrasting germination percentage to viability rate, observing germination under different environmental growth conditions, comparing emergence under differing media matrices, assessing the response of seed to different phytohormones, and monitoring imbibition over time under diurnal temperatures. Our results indicate that a standard potting mix is sufficient for germination and growth, that high concentrations of salt are inhibitory to germination, that ABA is inhibitory to germination, and that 6-BAP and GA are neither inhibitory nor promotive of germination. Most interestingly, our results also indicate that the ecology of the mother plant in the previous year of growth will play a significant role in the subsequent germination of silverleaf seed. As such, our study provides an important look at the influence of ecology on germination of silverleaf nightshade and also provides recommendations for the development of a propagation system under chamber or greenhouse conditions. Finally, our study gives important clues for the dynamics of seed bank accumulation, mechanisms of drought persistence, as well as primary and secondary dormancy in the continuing effort to better control this economically important and agro-ecologically disruptive weed.