Exploring Source-Sink Relationship for the Formation of Grain Yield in Sunflower

Developing high-yielding varieties of sunflower as oilseed staple crops requires knowledge of physiological and molecular mechanisms involved in yield formation. Source strength, sink demand, and their interactions play crucial roles in the yield formation of sunflowers. The persistence of assimilate flux to the developing grains mainly determines sink demand. There was no information on the molecular mechanism for assimilate flux to the sink organ of sunflowers. To shed light on molecular events engaging in assimilate flux to sink organs, two experiments were carried out on five sunflower inbred lines differing in their grain yields. Source-related parameters (such as leaf biomass, area, and number) and sink-associated attributes (such as floret number at the first anthesis and capitulum biomass and diameter, in addition to changes in biomass of capitulum and stem, at the first anthesis with those at physiological maturity) were evaluated across all the inbred lines. The Invertase gene expression level was measured on the receptacle base of three inbred lines, showing discrepancies in the source, sink, and grain yield performances. While no significant correlation was found between source strength and sink demand with grain yield, the results showed that higher grain yield was likely attributed to the persistence of assimilate flux to the capitulum base during grain filling. This phenomenon is discussed to be due to higher Invertase activity in the receptacle base.

کلیدواژه ها:

Assimilate flux ، Invertase gene expression ، Source-to-sink relations.