ISSN:
1573-5036
Keywords:
15N dilution method
;
nodule
;
non-nodulating Phaseolus vulgaris
;
single treatment method
;
split application
;
time of nitrogen supply
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The effect of mineral nitrogen applications at different growth stages on N2 fixation, nodulation and shoot dry weight of two cultivars of common bean (Phaseolus vulgaris L.) was investigated in a greenhouse experiment. Mineral nitrogen was split into two unequal doses (5 and 25 mg N kg-1 soil). The main fertilizer dose was applied at sowing or at the vegetative stage, V6. N2 fixation was determined by the 15N dilution method combined with the single treatment method. By physiological maturity, shoot dry weights and grain yields did not differ between cultivars, but cv. Puebla fixed more N2 than cv. Negro Argel. The timing of the main nitrogen application (25 mg N kg-1 soil) did not affect final shoot dry weights and grain yields. At the V6 vegetative stage, 28 days after the application of 25 mg N kg-1 soil, the nodule numbers of cv. Puebla and cv. Negro Argel were 14% and 82%, respectively, of the nodule numbers of plants which received 5 mg N kg-1 soil at sowing. Also, nodule dry weight and acetylene reducing activity per plant at V6 were reduced following the application of 25 mg N kg-1 soil at sowing. However, when 25 mg N kg-1 soil were applied at sowing and 5 mg N kg-1 soil at the V6 stage, 55% and 45%, respectively, of the final (R8) nitrogen accumulation in the shoots of cv. Puebla and cv. Negro Argel was derived from N2 fixation. Less N was derived from the atmosphere (45% and 35% in the shoots of cv. Puebla and cv. Negro Argel at R8, respectively) when 5 mg N kg-1 soil was applied at sowing and 25 mg N kg-1 soil at V6. The delayed onset of N2 fixation of the Phaseolus vulgaris-Rhizobium symbiosis as a consequence of the main nitrogen application at sowing was less detrimental to the quantity of symbiotically fixed nitrogen of both cultivars than the effect of 25 mg N kg-1 soil during vegetative growth.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00010337
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