Effects of Temperature and Water Stress on Some Floral Nectar Characteristics in Ipomopsis longiflora (Polemoniaceae) under Controlled Conditions

Abstract

Plants in laboratory experiments were exposed to constant day (16 h) temperatures of 20 C, 30 C, and 35 C with night temperatures of 20 C (8 h) and three levels of water stress (low, moderate, and high) at each temperature regime. The percentage of sucrose in the nectar was reduced by a small but statistically significant amount at the highest test temperature but was not affected by differences in water stress. Sugar concentration of the nectar was not affected by temperature or water stress. Nectar volume was significantly affected only by water stress. Flower size (corolla tube length) was affected by both temperature and water stress. No significant interactions between temperature and water stress were detected in any experiment.