Data/hora: 10/06/2024 19:15:15

Provedor de dados: | Brazilian Journal of Microbiology
País: | Brazil
Título: | DROUGHT-INDUCED EFFECTS AND RECOVERY OF NITRATE ASSIMILATION AND NODULE ACTIVITY IN COWPEA PLANTS INOCULATED WITH BRADYRHIZOBIUM SPP. UNDER MODERATE NITRATE LEVEL
Autores: | Silveira,Joaquim Albenísio Gomes da; Costa,Roberto Cezar Lobo da; Oliveira,José Tadeu Abreu.
Data: | 2001-10-01
Ano: | 2001
Palavras-chave: | Glutamine synthetase; Leghemoglobin; Nitrate reductase; N2 fixation; Water stress; Vigna unguiculata (L.) Walp.
Resumo: | This study was carried out to establish comparative effects of drought and recovery on the nitrate assimilation and nodule activity related to N2 fixation in cowpea plants [Vigna unguiculata L. (Walp.)] previously inoculated with Bradyrhizobium spp. BR-3256 (CB-756) strain in the presence of 5 mol m-3 NO-3. Twenty-eight-day-old nodulated plants were submitted to water deprivation during 4 consecutive days and afterwards resupplied with nutrient solution during 2 days. The water deprivation caused a rapid increase in the nitrate content in root and a marked reduction in leaf nitrate reductase (NR) activity. In contrast nodule NR activity was slightly increased by water deprivation. Concomitantly, in nodules of water stressed plants, leghemoglobin and glutamine synthetase (GS) activity declined and a progressive reduction in ureide-N concentration in xylem sap was observed. Leaf-NR activity increased rapidly after rehydration while leaf nitrate content declined. In contrast both GS activity and soluble protein content in the nodule continued to decline in rewatered plants. In addition the concentration of leghemoglobin recovered well, while the xylem ureide-N content experienced a slight increase after rehydration. Despite the nitrate assimilation in leaves and the nodule activity had been both severely affected by water stress, the rapid recovery of nitrate reductase activity suggests that the nitrate assimilation process is less sensitive to drought/rehydration cycle when cowpea plants are nodulated in presence of moderate nitrate level.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822001000300005
Editor: | Sociedade Brasileira de Microbiologia
Relação: | 10.1590/S1517-83822001000300005
Formato: | text/html
Fonte: | Brazilian Journal of Microbiology  v.32 n.3 2001
Fonte: | info:eu-repo/semantics/openAccess