Modelling The Effect of Temperature on Rhizome sprouting in the Invasive Weed Silverleaf Nightshade (Solanum elaeagnifolium)

Silverleaf nightshade (Solanum elaeagnifolium Cav.), a noxious, highly invasive perennial weed, poses a significant threat to irrigated summer crops, vegetables, and orchards. This weed has the ability to reproduce both sexually, through seed production, and asexually, via an extensive underground rhizome network, the latter being major role in the weed’s invasion, establishment, and persistence. Our aims were thus to assess the impact of temperature on rhizome sprouting for fragments of different lengths and to model the sprouting dynamics. The influence of temperature on the sprouting of rhizome fragments (2.5, 5, 7.5, or 10 cm long) was investigated in growth chambers at eight temperatures ranging from 10–45 C. The highest sprouting proportions for 10-cm rhizome fragments were recorded at 30 and 35 C in complete darkness. The highest sprouting time for all fragment lengths was observed at 15 C in complete darkness. Modeling sprouting rates as a function of temperature gave the cardinal temperatures for the four different rhizome fragment lengths, with values of: T b (base temperature) 12.80, 9.34, 9.14 and 9.50 C, T o (optimal temperature) 38.90, 36.60, 35.16 and 34.86 C, Tc (ceiling temperature) 39.80, 40.08, 40.50 and 40.80 C for the rhizome length of 2.5, 5, 7.5 and 10 cm respectively. Based on these findings, the potential for S. elaeagnifolium to spread to new areas and possible new management strategies are discussed; these offer a novel approach for informed decision making regarding the control of this weed.