Gas-exchange activity, carbohydrate status, and protein turnover in root nodule subpopulations of field pea (Pisum sativum L. cv. Century)

Abstract

Root nodule ontogeny was followed in different parts of the root system of field peas (Pisum sativum L. cv. Century) to investigate the contribution to total nitrogen fixation by different nodule subpopulations. Seed-inoculated plants were grown to maturity in controlled-environment growth chambers. In a flow-through system nitrogenase activity (H2-evolution in air) and nodulated-root respiration (net CO2-evolution) were measured weekly or biweekly in different parts (top and mid) of the root system. Root nodule extracts were assayed for total soluble cytosolic protein, total heme, proteolytic capacity (at pH 7.0), soluble carbohydrates and starch. Total nitrogenase activity and nodule respiration were higher in the top zone, which was explained by differences in root and nodule mass. Nodule specific nitrogenase activity was similar in both zones, and gradually declined throughout the experiment. No differences were found between nodule subpopulations in the dry-matter specific concentrations of glucose, fructose, sucrose or starch. Neither did nodule concentrations of protein or leghemoglobin differ between the zones. Throughout reproductive growth, no decline was found in total or nodule specific nitrogenase activity, in any of the nodule subpopulations. Growth of the root nodules continued throughout the experiment, though growth of shoot and roots had ceased. The data gives no support for carbohydrate limitation in root nodules during pod-filling, since nodule respiration remained high, the concentration of soluble carbohydrates increased significantly, and the amount of starch was not reduced. We conclude that when this symbiosis is grown under controlled conditions, nitrogenase activity in nodules sub-sampled from the crown part of the root system is representative for the whole nodule population.Abbreviations: D W -dry weight; W A P -weeks after planting

Reaction of faba bean plants to soil and foliar N application and K nutrition

“…3). Gradual decline in nitrogenase activity throughout the ontogenesis of pea was observed by Vikman and Vessey (1993) and Wojcieska el al. (1993Wojcieska el al.…”

“…M a j o r decline in nitrogen fixation during reproductive growth has often been reported (Vikman and Vessey 1993, Kailerova 1984, Ruszkowska et al 1991, Zinkiewicz et al 1992. This raises a question whether the amounts of nitrogen fixed symbiotically are sufficient to meet the needs related to seed setting and formation.…”

Free sugar profile in cycads

“…Sucrose is the major sugar represented in legume root nodules that have been studied ( Streeter, 1991 ; Vikman and Vessey, 1993 ). Hence, whether sucrose would dominate the sugar profile in cycad coralloid roots was of interest.…”

Effect of Organic Manure and Nitrogen Fertilizer on Growth, Yield and Yield Components of Faba Bean Grown Under Toshka Condition

“…Biological nitrogen fixation has often been reported insufficient due to many studies (Vikman and Vessey, 1993). This raises the question whether we should apply nitrogen fertilizers in addition to symbiotic nitrogen fixation to the crop to meet the need for potential crop production or not?…”