Hybrid Cotton Pollination in Relation to Accumulated Degree Days

Hybrid cotton ( Gossypium spp.) pollination needs to be supplemented with honey bee ( Apis mellifera L.) colonies. However, the relative importance of this supplemental pollination at specified time intervals during cotton bloom has not been determined. Therefore, our study was conducted to determine the quantity and quality of hybrid seed produced as a result of pollination during four consecutive, equal degree‐day (DD) periods. Four hybrid cotton seed production fields were established in Lubbock County, Texas. Accumulated DD (base temperature = 15 °C) were recorded for each field and divided into four equal periods within fields. Native and honey bee visitation was monitored every 2 d by counting the numbers observed per 100 flowers on the A‐line. All cotton bolls were hand harvested and sorted by date of bloom. Following harvesting, ginning, and delinting, seeds were counted and weighed, and percent germination was determined. Although the native and honey bee visitation level was adequate throughout each DD period, linear regression analyses indicate that coefficients of determination ( r 2 ) were low for (i) percent boll set and number of bees (native and honey bees), and (ii) number of seeds per boll and mean number of bees (native and honey bees). Pollination during the earlier DD periods resulted in higher percent germination, larger number of seeds per boll, and higher seed weight than seeds resulting from pollination during the latter bloom periods. We conclude that with proper honey bee management and pollination timing, the quality of hybrid seed produced will be improved by using only that from the first half of the bloom period