The Effect of Cultivated and Wild Rice Varieties on the Nitrogen Balance of Flooded Soil

Difference in Natural Abundance of15N in Several Rice(Oryza sativaL.) Varieties: Application for Evaluating N2Fixation

“…Varieties or lines used here were selected on the basis of AR assays (4,10,11), N balance studies (2), and dependence on soil N as determined by the 15N uptake in plots with 15N depleted fertilizer (De Datta, IRRI, personal communication).…”

“…IR42, Hua-chou-chi-mo-mor and Rodjolele were selected as varieties with a high ability to enhance N gains based on N balance studies (2). IR42 also displayed a high plant-associated acetylene-reducing activity (ARA) expressed per g total plant dry weight (4,10,11).…”

“…IR42 also displayed a high plant-associated acetylene-reducing activity (ARA) expressed per g total plant dry weight (4,10,11). OS4 exhibits a low plant-associated ARA (3, 10) and a low ability to enhance N gains (2). In experiments A and B, plant-associated ARA was measured (4,11).…”

“…Rice varieties may differ in their reliance on N derived from photo dependent NlI-fixa-tion. Total N balance in a flooded rice-soil system enables to determine that the N gain is affected by the varieties and growing conditions (1,2,21), however, for routine screening it is a time-consuming and laborious method. Recently, a large number of reports dealing with the estimation of biological N2 fixation by the 15N dilution method have been published (5,15).…”

Isolement et activité nitrogénasique de Burkholderia vietnamiensis, bactérie fixatrice d'azote associée au riz (Oryza sativa L) cultivé sur un sol sulfaté du Viêt-nam

“…Des études de bilan d'azote (Watanabe et Lee, 1977 ;App et al, 1986 ;Wetselaar, 1981) ont démontré depuis longtemps l'importance du rôle des microorganismes fixateurs d'azote en riziculture irriguée traditionnelle. La fixation d'azote peut y être élevée (Roger et Ladha, 1992) (Ladha et al, 1987 ;Omar et al, 1989 ;Rahman et al, 1996 ;Roussos et al, 1980 ; Thomas-Bauzon et al, 1982) et peuvent représenter jusqu'à 80 % de la microflore totale (Watanabe et Barraquio, 1979 ;Barraquio et Watanabe, 1981).…”