Efeito de fonte externa de nitrogenio no transporte de compostos nitrogenados em plantas de soja glycine max (L.) Merril cultivar Santa Rosa

AUTOR(ES)
DATA DE PUBLICAÇÃO

1986

RESUMO

Soybean plants, innoculated with rhizobium japonicium, were grown in vermiculite with a nitrogen deficient nutrient solution in a greenhouse. The effect of NO-3 and NH+4 on nodule activity was studied in terms of N2-fixing capacity (acetylene reduction) and ureide and amino acid levels of the xylem sap. Nodulated plants were treated with nutrient solutions containing NO-3 (15mM), NH+4 (10mM), or without nitrogen (control) for 7 days close to flowering. NO-3 was found to inhibit nitrogenase (acetylene reduction) and bstrongly reduce the level of ureideos, but had not significant effect on the amino acid level.NH+4 inhibited nitrogenase at the same level as NO-3,but had a lower effect on ureide levels. On the other hand, the amino acid level increased substantially. The relative ureide content fell to low but similar levels for both these ions, such that this value may be suspect as an indicator of N2 fixation when NH+4 is present.NH+4 did not alter the levels of N-NH+4 , but increased slightly the level of NO-3. NO-3 caused slight increased in aspartic acid and a large increase in NO-3. The higher proportion of alantoic acid relative to allantoin was found to be even greater in plants growing on mineral N. The NH+4 ion had an intermediary effect on the two N-assimilatory processes with respect to the quantity of N transported to the aereal parts

ASSUNTO(S)

compostos nitrogenicos plantas - efeito do nitrogenio botanica

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