Mitigating water stress by increasing NO3−: NH4+ ratio in young Eucalyptus urophylla plants

Autor: Paulo Araquém Ramos Cairo, Milton Carriço Sá, Poliana Prates de Souza Soares, Naasoom Luiz Santos Mesquita, Raul Antônio Araújo do Bonfim, Matheus Ferreira Almeida, Sylvana Naomi Matsumoto, Leandro Dias da Silva, Mateus Pires Barbosa
Rok vydání: 2021
Předmět:
Zdroj: Trees. 36:81-91
ISSN: 1432-2285
0931-1890
Popis: Mixed N fertilization with NO3−:NH4+ ratio of 0.50:0.50 mitigates negative water stress effects on growth in young Eucalyptus urophylla plants. Plant tolerance to water deficit can be influenced by several factors, including the available ionic forms of fertilization. The goal of this study was to assess the effects of nitrate (NO3−) and ammonium (NH4+) ratios in N fertilization on growth-related morphophysiological and biochemical traits, with the aim of mitigating water stress in young Eucalyptus urophylla plants. A greenhouse experiment was arranged in a completely randomized design and factorial scheme 5 × 2, with different NO3−:NH4+ ratios (0.0:1.0 × 0.25:0.75 × 0.50:0.50 × 0.75:0.25 × 1.0:0.0) and water regimes based on irrigation at 90 and 30% of pot capacity. The results showed that water deficit inhibited plant growth, resulting in lower plant height, and smaller stem diameter, total leaf area, and leaf, stem and root dry mass. Decreases in stomatal conductance, net photosynthesis, and the content of reducing sugar and starch are involved in growth inhibition. Increasing the NO3−:NH4+ ratio can mitigate negative water deficit effects on leaf water potential, stomatal conductance, and photosynthesis. Furthermore, leaf nitrate reductase activity improves under mixed NO3−:NH4+ fertilization, compared with NO3– or NH4+ fertilization alone. Despite this, variations in N sources proved to be ineffective in preventing growth inhibition under water deficit. However, the NO3−:NH4+ ratio of 0.50:0.50 provided the best performance of morphophysiological traits, regardless of the water regime. This was particularly relevant at irrigation levels under 30% since fertilization with an NO3− ratio equal to NH4+ can mitigate water stress effects on plant growth, despite not preventing damage to morphophysiological traits.
Databáze: OpenAIRE
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