Temperature Effects on Huisache (Vachellia farnesiana (L.) Wight & Arn.) Seed Germination

Huisache (Vachellia farnesiana (L.) Wight & Arn.) is a pest tree species on rangelands throughout South Texas and is expanding in range and density, due in part to prolific seed production. We aimed to determine the optimum diurnally-fluctuating temperature conditions for huisache seed germination by testing scarified and nonscarified seed in four temperature treatments: 35/25, 30/20, 25/15, and 20/10°C. We used alternating 12-hour light/dark photoperiods in a growth chamber, and seed germination was recorded daily. Germination of scarified and nonscarified seeds at each temperature treatment was analyzed via ANOVA for a completely randomized design (with appropriate posthoc tests). Although total cumulative germination percentages were similar among temperature treatments, seeds in the 20/10°C temperature treatment germinated more slowly. In addition, scarified seeds germinated more quickly, and with greater total percent germination. Results show that huisache seeds can be expected to germinate over a wide range of temperatures, with germination slowing when temperatures are low. Because we found huisache seeds germinated slowly in cooler temperatures, landscape managers may consider prioritizing control efforts of recently-germinated seedlings following warmer, wetter weather.