Growth, yield, nutrient uptake and removal by sweet potato in response to nitrogen management with a chlorophyll meter

• Grant number: 21/12973-0
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2022
• End date: February 29, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Adalton Mazetti Fernandes
• Grantee: Adalton Mazetti Fernandes
• Host Institution: Centro de Raízes e Amidos Tropicais (CERAT). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated researchers: Emerson de Freitas Cordova de Souza ; Pablo Forlan Vargas

Abstract

The balanced nitrogen (N) supply for sweet potato (Ipomoea potatoes (L.) Lam.) is essential to obtain high yields. This study aims to evaluate the growth, yield, nutrient uptake and removal by sweetpotato in response to N fertilization management using a chlorophyll meter. For this purpose, it is sought to establish the best N sufficiency index (NSI) and N rate for sweetpotato fertilization, as well as the best way to manage N fertilization with these parameters. The experiment will have two phases in two cultivation sites. In Phase 1, the experimental design will be randomized blocks, in a 2+6x2 factorial scheme, with four replications. The treatments will have conventional N fertilization (50 kg ha-1), N reference fertilization (150 kg ha-1), and six NSI values (90-95%) associated with two application criteria (10 or 15 kg ha-1 N for each (1.0) percentage point below the treatment NSI value). In phase 2, the design will be randomized blocks with four replications and 5 treatments (control: no N; reference: 150 kg ha-1 N split applied; conventional: 50 kg ha-1 N split applied; +p+ ISN: 20 kg ha-1 N at planting + N at topdressing based on "phase 1 optimal rate and NSI"; -p+ISN: no N at planting + N at topdressing based on "phase 1 optimal rate and NSI ". It will be evaluated: NSI and N rate of maximum technical efficiency, relative chlorophyll index, leaf nutrient content, yield components and tuber yield, dry matter accumulation, nutrient uptake and removal, root quality, and measures of N use efficiency. Data from each phase will be submitted to ANOVA separately. In phase 1, the means of the treatments component of the factorial will be compared by LSD test (pd0.05) and the effects of NSI will be analyzed by regression (pd 0.05). In this phase, orthogonal contrasts will be performed between the factorial treatments and the conventional and reference treatments. In phase 2, the treatment means will be compared by the LSD test (pd0.05). (AU)