Plant growth regulators as a means of increasing honey bee visitation to male-sterile cotton

The honey bee, Apis mellifera L., is the major pollinating agent for production of commercial hybrid cotton seed (Gossypium hirsutum L.). To ensure maximum pollination, a means of maintaining within-field flower visitation is essential. Increasing the sugar concentration of floral nectar with foliar applications of plant growth regulators (PGRs) or herbicides may provide the means of obtaining desired pollination. A-line (male-sterile) plants were treated at early bloom with five PGRs to determine effects on floral nectar sugar concentration. Nectar samples from the intrafloral nectaries were tested for total sugar concentrations and specific concentrations of fructose, glucose, and sucrose. Samples were collected using microliter pipets and analyzed with a hand-held refractometer and high performance Uquid chromotography. Total seed weight, seed number, and lint weight were also recorded for each treatment. No differences (P> 0.05) were detected within any of these parameters when tested among treatments. Therefore, the possibility of increasing sugar concentration of floral nectar or honey bee visitation with plant the growth regulators used in this study was not demonstrated. Other chemicals or agricultural practices such as fertilizer rates or number of irrigations and irrigation timing may have had some effect on sugar concentration.