Rice varieties exhibit different mechanisms for Nitrogen Use Efficiency (NUE)

Abstract

Nitrogen use efficiency (NUE) is an important characteristic for increasing the yield and quality of rice grains and reducing the use of nitrogen fertilizers. This study evaluated parameters that contribute to NUE in two tropical japonica rice varieties contrasting in nitrogen remobilization efficiency (NRE) and nitrate-uptake kinetics: IAC-47 (bred for high-input farming), and Piauí (a landrace from the state of Maranhão, Brazil). The two varieties were grown with and without N supplementation at anthesis stage. Both varieties received urea equivalent to 60 kg N ha -1 in the first ten days after planting (DAP) and a subset of the two varieties received a supplementation with 40 kg N ha -1 at anthesis stage, composing a treatment with supplementation (Ts). The control treatment (Tc) was constituted of the plants that did not receive nitrogen supplementation at anthesis. We analyzed the nitrogen soluble fractions, soluble sugars, dry matter production, total N, crude protein in grains, NUE parameters, and expression and activity of glutamine synthetase (GS). The N uptake after anthesis affected the total N content in the shoots and grains of both rice varieties. In treatments with and without N supplementation, the nitrogen uptake efficiency (NUpE) was higher in IAC-47 than in Piauí plants. The NRE, a desirable characteristic for plants grown with low N input, was around two times higher in the Piauí plants that were not supplemented with N during anthesis. panicles of piauí plants grouwn without N supplementation presented higher expression of the glutamine synthetase gene OsGS1.3 post-anthesis. The results indicate that NRE is the primary factor contributing to NUE in rice varieties adapted to a low N supply, whereas improved varieties exhibit a higher NUpE.

Variedades de arroz locais como alternativas viáveis para uma agricultura mais sustentável

“…O Estado do Maranhão, marcado por fluxos intermitentes de nutrientes no solo, devido à alternância de períodos chuvosos e secos, e historicamente um grande produtor de arroz, possui um grande banco de germoplasma, com variedades que guardam consigo diversas adaptações às condições de cultivo presentes naquela região. Características como a maior eficiência no uso de N e maior desenvolvimento radicular em condições de baixa adubação nitrogenada, vêm sendo identificadas em trabalhos desenvolvidos por pesquisadores no Laboratório de Nutrição Mineral de Plantas (LNMP) (Coelho et al, 2016;Santos et al, 2011).…”