Environmental Influences on Nectar Secretion

1. By increasing humidity the secretion from nectaries of water but not that of sugar is increased. 2. Excessive water supply lessens the sugar surplus in the parts of the flower. 3. Dilution and washing by rain cause much of the sugar of nectar to be lost. 4. Rate of secretion for both sugar and water increases with temperature up to a certain optimum. 5. Accumulation of sugar in the flower and its vicinity varies inversely as the temperature. 6. The optimum condition for sugar secretion is an alternation of low and high temperatures. 7. Variation of atmospheric pressure has no marked influence on secretion. 8. Sugar excretion is markedly diminished in darkness on account of limitation of the food reserves of the plant. Water excretion may or may not continue, depending upon the species. Removal of the leaves has the same deterrent effect. 9. The more favorable all conditions for growth and the more vigorous the plant, the greater is the amount of sugar secreted. 10. Nectar is most abundant early in the blooming season, other things being equal. 11. Accumulation and secretion of sugar is most pronounced near the time of the opening of the flower.