scholarly journals Physical Environment and Symbiotic Nitrogen Fixation VII. Effect of Fluctuating Root Temperature on Nitrogen Fixation

1969 ◽  
Vol 22 (4) ◽  
pp. 839 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Dark Period ◽  
Light Period ◽  
Continuous Illumination ◽  
Continuous Exposure ◽  
Rhizobium Trifolii ◽  
Symbiotic System ◽  
Root Temperature

The effect of exposing nodulated plants to daily periods of high, moderate, or low root temperatures was examined, using Trifolium 8ubterraneum and three strains of Rhizobium trifolii. With strains whose nitrogen fixation was severely retarded by continuous exposure to high root temperatures, the results from treatments involving exposure of 4, 8, 12, and 20 hr/day to 30�C and continuous illumination were consistent with the effect being on the rate of nitrogen fixation, without any permanent impairment to the symbiotic system. With a 12 hr/day light period, a daily 12-hr exposure to 30�C during the dark period reduced total nitrogen fixation as much as exposure to 30�C during the light period. This indicated that the rate of nitrogen fixation during normal dark periods could be as high as that during periods of illumination. Similar conclusions were drawn from the same type of experiments involving daily exposure to moderate (14 and 16�C) root temperatures.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation. IV. Faotors Affecting the Early Stages of Nodulation

1967 ◽  
Vol 20 (6) ◽  
pp. 1087 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Light Period ◽  
Root Temperature ◽  
Early Stages ◽  
Temperature Conditions ◽  
General Decline ◽  
Effect Of Light

The influence of root temperature on the initial nodulation of Trifolium subterraneum L. was examined, and observations were made on the effect of light period and shoot temperature on this character. The maximum constant root temperature at which nodules would form was 33�0, and the minimum was in the vicinity of 7�0. The most rapid initial nodulation (2-3 days after inoculation) was observed at 30�0, and plants growing at this temperature had the highest rate of nodule appearance. Below 22�0, there was a marked increase in the "time to first visible nodule" and a general decline in the rate at which they appeared. Differences were observed in the time to first visible nodule, and in the rate of nodule appearance, between different cultivars of T. 8ubterraneum. There was an indication of a temperature X cultivar interaction for these characters. With the three strains of Rh. trifolii used, no differences in their ability to form nodules were observed, although it was known that their subsequent symbiotic behaviour differed under certain root temperature conditions.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation II. Root Temperature Effects on the Relative Nitrogen Assimilation Rate

1965 ◽  
Vol 18 (2) ◽  
pp. 295 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Temperature Effects ◽  
Nitrogen Assimilation ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Bacterial Strains ◽  
Root Temperature ◽  
Relative Growth ◽  
Relative Growth Rates

Nitrogen fixation by six varieties of Trifolium subterraneum L., each inoculated with a number of strains of Rhizobium trifolii, was examined over a range of root temperatures. Significant differences in the rate of nodule establishment and early nitrogen fixation were found between varieties, and between bacterial strains. In order to minimize the effect of such differences, relative nitrogen assimilation rates (RN) and relative growth rates (R w) were used to compare the different legume-bacteria associations.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation III. Root Temperature Effects on Shoot and Root Development and Nitrogen Distribution In Trifolium Subterraneum

1966 ◽  
Vol 19 (2) ◽  
pp. 219 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Temperature Effects ◽  
Shoot Growth ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Trifolium Subterraneum ◽  
Root Temperature ◽  
Nitrogen Distribution ◽  
Root And Shoot Growth

Root and shoot growth, and the distribution of nitrogen to the roots and shoots, were examined in five varieties of Trifolium subterraneum. The plants were grown between 5 and 30�0 root temperature, and received their nitrogen from root nodules, or as ammonium nitrate.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation

1963 ◽  
Vol 16 (1) ◽  
pp. 28 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Rhizobium Trifolii

The effect of root temperatures (5-30�0) on the growth and symbiotic nitrogen fixation by nodulated plants of four varieties of Trifolium subterraneum L., inoculated with each of two strains of Rhizobium trifolii, was examined.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation. V. Effect of Time of Exposure to Unfavourable Root Temperatures

1967 ◽  
Vol 20 (6) ◽  
pp. 1105 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Rhizobium Trifolii ◽  
Optimal Temperature ◽  
Three Stages

Symbiotic nitrogen fixation by Trifolium subterraneum L., inoculated with three strains of Rhizobium trifolii Dang., was examined over the range of root temperatures 8-28�0. The plants were transferred from an optimal temperature for nitrogen fixation (23�0) to other temperatures at three stages, namely (1) immediately after inoculation, 3 days after germination, (2) 14 days after germ� ination, when nitrogen fixation had commenced, and (3) 21 days after germination, when the plants had been fixing nitrogen for at least 7 days. Nitrogen increase and dry weight accumulation were determined for two growth periods-days 14-21 (I) and days 21-28 (II)

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation VI. Nitrogen Retention Within the Nodules of Trifolium Subterraneum L

1969 ◽  
Vol 22 (4) ◽  
pp. 829 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Effective Strain ◽  
Nitrogen Retention ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Root Temperature ◽  
Protein Nitrogen ◽  
The Difference ◽  
Nodule Tissue

The effect of bacterial strain and root temperature on the retention of nitrogen in the root system of Trifolium Bubterraneum plants was re-examined. The root systems of plants nodulated by the moderately effective Rhizobium trifolii strain NA30 possessed a higher percentage nitrogen than those nodulated by the fully effective strain TAl, although the number of nodules formed by each strain was similar. The difference was due to a greater weight of nodule tissue on the NA30-nodulated plants, and also to a higher percentage nitrogen in the NA30 nodules; this latter effect was due to a higher concentration of non-protein nitrogen. The overall effect of these differences was to reduce the amount of nitrogen translocated to the shoots of the NA30 plants, in both absolute terms and as a proportion of the total amount of nitrogen fixed. Another difference between the two strains was the rate of nitrogen fixation per unit (dry weight or leghaemoglobin content) of nodule tissue.

INFLUENCE OF ROOT TEMPERATURE ON THE EARLY GROWTH AND SYMBIOTIC NITROGEN FIXATION OF NODULATED LOTUS CORNICULATUS PLANTS

1970 ◽  
Vol 50 (5) ◽  
pp. 569-575 ◽  
Author(s):  
H. T. KUNELIUS ◽  
K. W. CLARK
Keyword(s):  
Nitrogen Fixation ◽  
Ammonium Nitrate ◽  
Environmental Conditions ◽  
Symbiotic Nitrogen Fixation ◽  
Lotus Corniculatus ◽  
Early Growth ◽  
Birdsfoot Trefoil ◽  
Nodule Formation ◽  
Root Temperature ◽  
Nitrogen Yields

Three birdsfoot trefoil (Lotus corniculatus L.) cultivars, inoculated with one of six Lotus rhizobia strains or dependent on ammonium nitrate, were grown in diSPo growth pouches under controlled environmental conditions at five root temperatures (9–30 C) for 35 days after nodule formation. When the plants were dependent on symbiotic nitrogen fixation, the highest dry weights and nitrogen yields per plant were obtained at 18 or 24 C depending on symbiotic combination. At 9 and 12 C, nitrogen fixation was depressed and the growth was poor. The dry weights of plants at 9 C were 19 to 45% of those at 24 C. At 30 C the growth and nitrogen fixation were generally depressed. At all root temperatures the growth of plants dependent on symbiotic nitrogen fixation was inferior to that of plants receiving combined nitrogen (NH4NO3). Significant interactions indicate that the nitrogen fixing ability of cultivars was dependent on both root temperature and the strain of Lotus rhizobia.

Root Temperature and Symbiotic Nitrogen Fixation

Nature ◽  
1961 ◽  
Vol 191 (4793) ◽  
pp. 1080-1081 ◽  
Author(s):  
A. H. GIBSON
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Root Temperature

PHOTOPERIODIC RESPONSE IN GERMINATION OF SEED OF CERTAIN TREES

1956 ◽  
Vol 34 (3) ◽  
pp. 377-388 ◽  
Author(s):  
O. Vaartaja
Keyword(s):  
Tree Species ◽  
Dark Period ◽  
Photoperiodic Response ◽  
Betula Pubescens ◽  
Light Period ◽  
Illumination Intensity ◽  
Effect Of Temperature ◽  
Continuous Illumination ◽  
Running Water ◽  
Photoperiodic Responses

Unstratified seeds of Betula pubescens Ehr. and B. verrucosa Ehr. exhibited low or no germination at temperatures from 10° to 20 °C. unless exposed to continuous illumination or illumination interrupted only by a short daily dark period. Germination was high even under a short primary light period if the long dark period was divided into two short ones by an additional daily light period. Besides these true photoperiodic responses, germination was slightly correlated to illumination intensity and to the amount of light. Germination was somewhat reduced when the illumination intensity was either decreased or increased from an optimum. At temperatures of 20° to 25 °C., germination was fair, even under a short daily light period. At still higher temperatures no light was needed for maximum or nearly maximum germination. Seeds of three other tree species also germinated better if exposed to long light periods, but the differences were small or not significant statistically. In most of the experiments the effect of temperature was separated from that of light by using running water as the germination medium. The antibiotic Rimocidin as well as various other chemicals and ultrasonic treatments failed to affect the germination of B. verrucosa.

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