Agronomy and Horticulture, Department of
First Advisor
Nicolas Cafaro La Menza
Committee Members
James E. Specht, Patricio Grassini, Jose F. Andrade, John Linquist
Date of this Version
12-2024
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Agronomy
Under the supervision of Professor Nicolas Cafaro La Menza
Lincoln, Nebraska, December 2024
Abstract
Soybean [Glycine max (L.) Merr.] seed yield is influenced by the seasonal availability of resources (i.e., nutrients, light, and water). While nitrogen (N) supply is becoming a soybean yield-limiting factor, the N-induced effect in seed yield components is still unclear. The objective of this research was to assess the effect of N supply on soybean yield components distribution within the canopy. A Full-N treatment, which provided the crop with ample N supply, was compared against a Zero-N treatment in which the crop relied on soil N and biological N fixation at nine high-yielding irrigated soybean environments in Nebraska, with known levels of N limitation. Soybean seed yield components were determined at every node and grouped into five canopy sections. Seed yield ranged from 4,378 to 7,314 kg ha-1 across environments and treatments. The greater N availability in the Full-N increased yield by 984 kg ha-1 in comparison to Zero-N; via +253 seeds m-2 (7%) and +16 mg seed-1 (11%). N-induced responses in seed yield occurred in the lower (nodes 0-4) , middle (nodes 13-18), and middle-upper sections (nodes 13-18). (nodes 0-4 and 9-18). Seed number and pod number increased in the middle-upper section. Notably, individual seed weight increased in all node sections. The seed number per pod response to N was negligible. The seed abortion within pods was 8%, but the Full N treatment reduced it by one percentual point. This study comprehensively examined the effects of N availability on soybean yield components within the canopy during their sequential establishment.
Advisor: Nicolas Cafaro La Menza
Comments
Copyright 2024, Lucia Bonfanti. Used by permission