Submitted to: Northern Nut Growers Association Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 2, 2008
Publication Date: N/A
Technical Abstract: Eastern black walnut (EBW) is an excellent choice for agroforestry practices in the eastern United States, because of its value for nuts and timber. There appears to be competing sinks for photosynthate in young trees early in the growing season; however growth data to support such a hypothesis are lacking. This experiment was conducted to provide such data. Monthly variations in trunk diameter and tree height was followed for three stands of EBW that vary in genotype (native versus named genotypes selected for nut quality), age (1 to 12 years-old) and management for 3 years located within 3 km of each near Booneville AR. Seasonal patterns in nut growth were monitored for 2 years. In addition patterns of nut abortion were followed in one stand. Analysis of variance indicated that main effects of years, stands and months significantly affected trunk diameter and tree height measurements. Tree height was significantly affected by interactions among the main effects of stands and years, whereas trunk diameter was not. No significant increase in either trunk diameter or tree height was observed after August during the growing season, indicating that above ground vegetative organs are active photosynthate sinks early in the growing season. After fertilization, most nut abortion occurred before August. These results substantiate earlier claims there are competing sinks for photosynthate in EBW seedling trees early in the season. A better understanding of how these sinks compete for photosynthate could lead to management practices that reduce nut abortion and thus increase nut qualities in EBW.