The influence of temperature and nitrate on vegetative growth and nitrogen accumulation by nodulated soybeans

Abstract

Acetylene reduction growth rate KEY WORDSGlycine max (L.) Merrill Leaf number N 2 fixation Relative SUMMARY Inoculated soybeans [Glycine max (L.) Merrill] were grown in controlled environments to evaluate the relationship between temperature and applied NO3-N on growth rates, N accumulation, and acetylene reduction activity during the vegetative growth stage. Soybeans were grown at day/night temperatures of 22/18 and 26/22~ in sand culture with daily applications of 21.4 mM (high) and 2.1 mM (low) NO3-N in a complete nutrient solution for durations of 14, 21, and 42 days after emergence and with an N-free solution. Dry matter and N accumulation were greater at 26/22 than 22/18~ In general, both increased as the level and duration of applied NO3-N was increased. These increases were attributable to an abbreviation in the interval between emergence and onset of rapid growth. The presence and assimilation of NO3-N, even at the high level, did not inhibit development of functional nodules. Neither mass nor acetylene reduction activity of nodules was reduced by high NO3-N; however, the root mass was increased by NO3-N more than the nodule mass. There was an interaction between temperature and NOa-N on specific nodule activity as measured by acetylene reduction. The specific nodule activity was unaffected by NO3-N at 22/18~ but at 26/22~ the specific activity was lower in the absence of NO 3 -N than when NO 3-N was present. Apparently, rapid early growth at 26/22~ depleted cotyledonary reserves of N before nodules became active and, thereafter, the plants were unable to develop adequate leaf area to support nodule development and functioning. This result has implications in N fertilization of late-planted soybeans.

Nitrogen Assimilation Traits and Dinitrogen Fixation in Soybean and Common Bean

“…Imsande (1989), however, reported that N2 fixation during soybean podfill enhances seed yield compared to urea N assimilation. Other reports indicate that soybean grown in solution c ulture supplied with mineral N assimilates substantially more N than do modulated plants (Jones et al, 1981;Lathwell and Evans, 1951;Wych and Rains, 1979). Similar results have been reported only rarely from field experiments (Cassman et al, 1981;Thies et al, 1991).…”

Some regulatory aspects of [14C]methylamine influx intoPisum sativum L. cv. Feltham First seedlings

“…In practice a primary 'starter' dose of inorganic N has been found to improve the growth of a range of leguminous species e.g. pea (Oghoghorie and Pate 1971) and soybean (Jones et al 1981).…”

Nitrogen nutrition of seedling grain legumes: some taxonomic, morphological and physiological constraints

“…In some cases it has been found that seed N reserves are sufficient to last the young plants until nodules begin actively to fix nittogen (for exatnple Pi.sum arvense; Pate, 1958a). In other cases a period of N stress has been observed before nodules fix nitrogen (for example, Jones, Patterson & Raper, 1981;Hildebrand, Harper & Hymowitz, 1981, for Glycine max;Cookson, Hughes & Cootnbs, 1980;Fratico & Munns, 1982 for Pha.seolus vulgari.s). This has led to the practice of giving a dose of 'starter N' fertilizer, although in tnany tetnperate soils mineralization of organic nitrogen takes place when soil temperatures rise in spring (if sufficient soil moisture is available) and provides such a dose naturally (see also discussion in Sprent et al 1983).…”

“…Most of the C is in a highly reduced form (fat), and can apparently provide sufTieient energy to support growth of the young seedling since, after emergence, N is considered to be tnore limiting than C (Williams, De,Iong & Phillips, 1981). However, the extent of such a nitrogen limitation is environmentally conditioned, as the data of Jones et al (1981) show. Of the various temperature regimes used, one of 26/22 °C day/night led to a depletion of eotyledonary Table 1A, Areas of leaves al the lower nodes of three grain legumes.…”