Nitrogen use efficiency in Urochloa brizantha cv. Marandu with foliar inoculation of plant growth-promoting bacteria associated with nitrogen isotope in sustainable pasture management

• Grant number: 25/06835-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Reges Heinrichs
• Grantee: Matheus Haruichi Okazuka
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil
• Associated research grant: 23/13986-3 - Enhancing nitrogen use efficiency in urochloa brizantha cv. marandu: physiological and molecular responses to foliar inoculation of plant growth-promoting bacteria alongside different 15N doses for sustainable nitrogen fertilization management, AP.R

Abstract

Pastures are the basis of animal feed. The sustainability of the system involves the production of greater quantity and quality of forage, with reduced inputs, providing less impact. The objective of the study will be to evaluate the capacity of the strains of Azospirillum brasilense, Bacillus S26 and Bacillus N72 applied via foliar application, associated with doses of N, to promote the growth of Urochloa brizantha cv. Marandu, evaluating the use of the applied urea, through the isotopic technique, and influence on the nutrition, development and production of dry mass of the aerial part and roots. The experimental design will be four randomized blocks with four replications, there will be 11 treatments, totaling 44 experimental units. The treatments were: 1) control - without nitrogen fertilization, 2) fertilized with 80 kg ha-1 of urea and without inoculation, 3) fertilized with 40 kg ha-1 of urea and without inoculation, 4) fertilized with 40 kg ha-1 of urea plus foliar inoculation of A. brasilense, 5) fertilized with 40 kg ha-1 of urea plus foliar inoculation of Bacillus S26, 6) fertilized with 40 kg ha-1 of urea plus foliar inoculation of Bacillus N72, 7) fertilized with 40 kg ha-1 of urea plus foliar inoculation of A. brasilense + Bacillus S26 + Bacillus N72, 8) foliar inoculation of A. brasilense + Bacillus S26 + Bacillus N72, without nitrogen fertilization, 9) foliar inoculation of A. brasilense, without nitrogen fertilization, 10) foliar inoculation of Bacillus S26, without nitrogen fertilization, 11) foliar inoculation of Bacillus N72, without nitrogen fertilization. The variables to be analyzed will be plant height, number of tillers, relative chlorophyll index, leaf/stalk ratio, root dry mass, macronutrients (N, P, K, Ca, Mg and S) and micronutrients (Cu, Fe, Mn and Zn). The use efficiency (NUE) and recovery of N applied via fertilizer in palisade grass will be determined using the isotopic dilution technique with 15N. The data will be tested for normality of errors and variance. Significant results will be subjected to a mean comparison test using the Scott-Knott test and correlations. The work should allow us to observe that the efficiency of forage production with high nutritional quality and good rational management of pastures is fundamental to guarantee animal production, as well as pasture persistence. (AU)