ENVIRONMENTAL EFFECTS ON SEED SET IN OILSEED SUNFLOWER (Helianthus annuus L.)
Incomplete seed set of certain commercial sunflower hybrids may be caused by self-incompatability, partial fertility restoration, or other factors which could be affected by the environment. Three commercial hybrids and their fertile inbred parents were planted at five locations across the central plains area of the U.S. during 1978 and 1979. Relative number and weight of developed seed were determined from six of these environments. Little difference in seed set was observed between bagged and unbagged heads of two of the hybrids and their inbred parents. The bagged heads of the third hybrid and its B-line inbred parent had consistently lower seed set. Environment affected seed set significantly. The number of developed seed in percent was consistently less than the weight of viable seed in percent.