Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2003
Publication Date: 6/20/2003
Citation: WOOD, B.W., CONNER, P., WORLEY, R. RELATIONSHIP OF ALTERNATE BEARING INTENSITY IN PECAN TO FRUIT AND CANOPY CHARACTERISTICS. HORTSCIENCE. 2003. v.38. p.361-366. Interpretive Summary: Alternate bearing is the economically most important biological problem associated with pecan farming. The fundamental causes of alternate bearing are poorly understood. A study of the linkage between alternate bearing and developmental characteristics (i.e., fruit ripening, leaf retention, foliar health, and foliation periods) has identified a short post-ripening foliation period as being key to reduced alternate bearing. This knowledge is important in the development of improved cultural and pest management practices and in breeding of improved cultivars.
Technical Abstract: Alternate bearing is a major economic problem for producers of pecan nuts [Caryra illinoinensis (Wangenh.) K. Koch], yet a fundamental understanding of alternate bearing remains elusive. Nut yields (over a period of up to 78 years) from a commercial-like orchard of 66 cultivars was used to calculate alternate bearing intensity (I). Best-fit regression analysis indicates no association between I and fruit ripening date (FRD) or nut volume; although, there was moderate association with post-ripening foliation periods (PRFP) in that I tends to decrease as the length of the PRFP decreases. Multiple regression models indicated that FRD and not volume were poor predictors of I; however, PRFP possessed significant inverse predictive power. Late-season canopy health, as measured by percentage of leaflet retention, decreased as FRD approached early-season ripening. Late-season photoassimilation rate was higher on foliage of trees with late FRDs than those with mid- or early-season ripening dates. These data provide new insight into the complex nature of alternate bearing in pecan and provide evidence for modifying the existing theories of alternate bearing of pecan.