Genotype by environment interactions in the nectar production of Echium vulgare

Abstract

1. Genotype by environment interactions for nectar production in Echium vulgare were studied. Nectar production was measured under high and low-water treatments for high and low nectar-producing genetic lines in a growth chamber. In the field the response of nectar production and pollinator behaviour to water availability for potted plants chosen from field populations was studied. 2. Plants selected from high-nectar lines produced significantly more nectar than those selected from low-nectar lines. Nectar production thus had a heritable component. 3. Under high water conditions plants produced more nectar than under low water conditions. The increase in nectar production under high water availability was strongest for the low-nectar plants, demonstrating a genotype by environment interaction. Only under dry conditions, which usually prevail during the flowering period of E. vulgare, high and low-nectar plants differ in nectar production. 4. Plants selected from high-nectar lines had a significantly higher root mass and root: shoot ratio. This suggests that they are less affected by low water availability and thus able to maintain high nectar production under dry conditions. 5. In the field, high-nectar plants produced significantly more nectar but did not receive more pollinator visits. Watered plants produced significantly more nectar and did receive an enhanced pollinator service. When watered, nectar production and pollinator service was similar for high and low-nectar plants. © 2005 British Ecological Society.