Elsiddig A.E. Elsheikh

NODULATION AND N2 FIXATION BY SOYBEAN INOCULATED WITH SALT-TOLERANT RHIZOBIA OR SALT-SENSITIVE BRADYRHIZOBIA IN SALINE SOIL

Nodulation of soybean by a salt-tolerant Rhizobium strain USDA 208 and a salt-sensitive Bradyrhizobium strain RCR 3407 (CB1809) was evaluated in saline soil in the glasshouse. No significant differences in shoot and root dry weight, nodule number and nodule weight between the salt-tolerant Rhizobium strain and the salt-sensitive Bradyrhizobium strain were found. Nodulation of soybean was reduced more than 50% by the equivalent of 34.2 mm NaCl in soil. The specific activity of nodules formed by both strains was also reduced by salinity. Nodulation was more sensitive than plant growth to salinity. The salt-sensitive strain was more effective than the salt-tolerant strain under non-saline conditions, but the salt-tolerant strain fixed more N2 than the salt-sensitive strain under saline conditions.

Effect of malt pretreatment on phytic acid and in vitro protein digestibility of sorghum flour

Sorghum seeds of cultivar Wad Ahemed (phytate: 2.7 mg/g, tannin: 0.96% and 2 h pepsin digestion: 18%) were germinated for three days to obtain 1-, 2- and 3- days old sorghum malts. Sorghum malt was added in concentrations of 1, 2.5, 5, 7.5 or 10% to sorghum flour. The mixtures were incubated with shaking for 0, 30, 60, 90 or 120 min. Phytic acid and in vitro protein digestibility were assayed for all treatments. The results revealed that phytate content was significantly reduced. The 10% 3-day-old malt after 120 min incubation, reduced the phytate content by 83%. The in vitro protein digestibility (IVPD) was significantly improved as a result of malt pretreatment. The rate of reduction of phytate content and the rate of increment in IVPD increased with time of incubation, age and concentration of the malt.

Salt effects on survival and multiplication of chickpea and soybean rhizobia

Abstract Fourteen strains of chickpea rhizobia. eight strains of soybean rhizobia and eight strains of soybean bradyrhizobia were screened for their tolerance to different concentrations of NaCl. Assessment of visible turbidity after 14 days indicated 15 strains of both chickpea and soybean rhizobia tolerant of 0.34 m NaCl. Most fast-growers were more salt-tolerant than the slow-growers. Three salt-tolerant strains were further tested for their tolerance to different salts. MgCl; was the most inhibitory salt. and soybean rhizobia were slightly more tolerant than chickpea rhizobia. Prior exposure to salt did not alter the subsequent response to the same or different salts and the same or higher concentrations. A 2% mixture of salts more representative of conditions in saline soils had no effect on survival of strains which initially multiplied in 2% NaCl but then died.

Effect of Rhizobium inoculation, organic and chemical fertilizers on proximate composition, in vitro protein digestibility, tannin and sulphur content of faba beans

Abstract A field experiment was carried out to investigate the effect of Rhizobium inoculation, sulphur, nitrogen and chicken manure on proximate analysis, in vitro protein digestibility (IVPD) tannin and sulphur content of faba beans. The results showed that Rhizobium inoculation, sulphur, nitrogen and chicken manure treatments significantly ( P ≤ 0.05) increased protein, IVPD and tannin content. Ash, moisture, fat and crude fibre content varied in their response to different fertilizers. The inoculation results were as good as the addition of 40 kg N ha −1 and the efficiency of inoculation can be improved by the addition of fertilizers and/or amendments. Fertilization of faba beans with nitrogen, sulphur or chicken manure not only increased yield, but also improved seed nutritional value. Chicken manure is a promising fertilizer, not only because it increases yield but because it has a significant effect in improving seed protein and IVPD. Sulphur treatments significantly ( P ≤ 0.05) increased the protein IVPD, tannin and sulphur content in seeds.

Response of chickpea and soybean rhizobia to salt: osmotic and specific ion effects of salts

Abstract Chickpea Rhizobium strain 2-ICAR-SYR-Ch-184 showed different responses (in terms of growth and survival) to a range of different salts. The chloride ions of Na, K and Mg were found to be more toxic than the corresponding sulphate ions. The osmotic effect was studied using polyethylene glycol (PEG), glycerol and sorbitol to raise the osmotic pressure to −1.0 and −2.0 MPa. PEG was toxic even at low concentrations. However, there was good growth at −1.0 and −2.0 MPa using glycerol and sorbitol. Although, the sensitivity of the strain to NaCl was increased at higher osmotic pressures, the harmful effect of salts on the growth of this strain could be attributed more to the specific ion effect rather than the osmotic effect. The influence of various organic osmotica on the growth of chickpea rhizobia and soybean rhizobia and bradyrhizobia was studied in salt-stressed media. Chickpea Rhizobium strain 2-ICAR-SYR-Ch-Ch184 showed an increase in final cell density when glutamate was added to 0.34 m NaCl. All other strains showed no improvement in growth with the addition of glutamate. Glycine betaine did not relieve the inhibition of growth of all strains except for a slight improvement in the growth of the salt-sensitive soybean Bradyrhizobium japonicum strain RCR 3407 at 0.08 m NaCl. However, all tested strains used glycine betaine as a sole carbon source regardless of the presence or absence of NaCl.

Rhizobia and bradyrhizobia under salt stress : possible role of trehalose in osmoregulation

Seven rhizobium fredii strains and seven Bradyrhizobium japonicum strains were grown in defined medium with or without 20mm trehalose in the presence or absence of NaCl. Trehalose had no effect on the growth rate of the strains in the absence of NaCl, but increased the growth rate of some strains in the presence of NaCl. Bradyrhizobium japonicum strain RCR 3827 was completely inhibited by 0·08m NaCl in absence of trehalose, but multiplied when trehalose was added. The results indicate that trehalose may act as an osmoregulator in these strains of Rhizobium and Bradyrhizobium.

The effect of Rhizobium inoculation and chemical fertilization on seed quality of fenugreek

Proximate composition and quality of seeds of two fenugreek cultivars were examined for their response to inoculation, nitrogen fertilization and/or molybdenum application in two field experiments. Mo significantly (p≤0.05) increased 1000-seed weight and protein content of seeds. N had no significant effect on the quality of the seeds. Inoculation significantly (p≤0.05) increased fat, fibre and protein contents. The results indicate that fenugreek inoculation with compatible and effective rhizobia can improve the seed composition and quality.

The effect of Bradyrhizobium inoculation on yield and seed quality of guar (Cyamopsis tetragonoloba L.)

Bradyrhizobium strains TAL 169 and TAL 1371 (introduced) and strains ENRRI 16A and ENRRI 16C (local) were used to inoculate five guar cultivars, namely, HFG-75, HFG-182, HFG-363, HFG-408 and WB-195 in a factorial field experiment. The objective of the experiment was to study the eAect of inoculation on yield, proximate analysis and mineral composition. Most of the Bradyrhizobium strains significantly increased yield, protein, crude fibre, and mineral content. The locally-isolated strains aAected these parameters more than the introduced ones. This study revealed that inoculation with Bradyrhizobium strains improved yield and seed quality of guar. # 1999 Published by Elsevier Science Ltd. All rights reserved.

Effect of cooking on anti-nutritional factors and in vitro protein digestibility (IVPD) of faba bean grown with different nutritional regimes.

A field experiment was carried out to study the effect of cooking on IVPD and anti-nutritional factors of mycorrhizal-inoculated, phosphorus- and sulphur- fertilized faba bean plants. The results indicated that cooking significantly increased protein digestibility for the control and all treated samples. The increased IVPD was a consequence of significant reduction in antinutritional factors (tannins and phytic acid).

Response of chickpea and soybean rhizobia to salt: Influence of carbon source, temperature and pH

Abstract Chickpea and soybean rhizobia showed patterns of utilization of carbon sources characteristic of fast-growers in the absence of NaCl. Bradyrhizobium japonicum strain RCR3407 shared some characteristics of both fast- and slow-growers. Out of four chickpea rhizobia and four soybean rhizobia and bradyrhizobia only chickpea Rhizobium strain 2-ICAR-MOR-Ch-192, soybean Rhizobium strains USDA 191 and USDA 201 were able to utilize some carbon sources in the presence of 0.25 m NaCl. All chickpea and soybean rhizobia were able to grow at 25 and 37°C in YEMA (yeast extract mannitol agar). but not at 45°C. The effect of four temperatures, three pH values and three NaCl concentrations on growth and multiplication of chickpea Rhizobium strain 2-ICAR-SYR-Ch-184 showed that salt-stress was more severe at alkaline pH and lower temperatures. The results indicate that tolerance to salt by rhizobia is dependent upon pH, temperature and carbon source.