摘要:

Solution culture, greenhouse and field experiments were conducted to compare the effect of NH.‐N and NO3,‐N on growth and yield of barley (Hordeum vulgareL.). In a solution culture experiment, barley grew more with NO3, than with NH4, particularly at high N concentrations. The effect was not much altered by buffering the solution pH with CaCO3. In a greenhouse experiment, with 10 soils which received 30 μg N g‐1, barley yields were greater with NO3, than with NH4, when soil pH was less than 6.0. Yield from NH4.‐N, expressed as a % of yield from NO3‐N, correlated well with soil pH (r=0.88**). In another greenhouse experiment, urea or (NH4)2‐SO4, when placed in a band with or without thiourea, remained substantially as NH4, in the soil, and subsequently plant growth was reduced. The field experiments which received N fertilizers in the spring, did not show much difference in grain yield of barley between NH4and NO, sources. In 16 field experiments on acid soils (pH 4.5 to 5.8), the average grain yield was similar with NH4NO3and with (NH4)2SO4. In 10 other field experiments on soils with pH values ranging from 6.0 to 8.4, yields were not influenced by N source or addition of nitrification inhibitors to the NH4‐based fertilizers. Because of possibility for loss of NO3‐N through denitrification and leaching, the NH4form might be preferable in the field.

ISSN:0010-3624    

DOI:10.1080/00103628809367994

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The acidity of alfisols and ultisols may be unfavorably increased for blueberry production by the use of specific nitrogen (N) fertilizers. Several ammonium containing fertilizers were evaluated for their effects on rabbiteye blueberries (Vaccinium asheiReade). Rooted ‘Tifblue’ cuttings were grown in a 1: 1 peat: Lilbert loamy fine sand mix for 90 days. After establishment, plants were moved into the glasshouse and fertilized four times at 90‐day intervals with one of six N sources at one of four rates. Nitrogen sources were (NH4)2SO4(AS), NH4NO3(AN), urea, urea‐NH4NO3(UAN), Nitro‐form (NF) and sulfur coated urea (SCU). Rates of N per application were equivalent to 0, 112, 224, or 336 kg/ha. The application of the high rate of each N source reduced plant growth. The 112 and 224 kg/ha N treatments increased growth compared to no nitrogen treatments. When comparing N sources, SCU treatments produced the greatest plant growth and AS treatments the lowest. Sulfur coated urea had less effect on soil pH and Al than other sources. Poor growth with AS was caused by the combined effects of decreased soil pH, increased soil electric conductivity (EC) and increased exchangeable aluminum. Plant leaf N increased with increasing N rate. Nitrogen sources which produced the greatest plant growth had the lowest N levels.

ISSN:0010-3624    

DOI:10.1080/00103628809367995

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The nutritional status of two forest communities, one on a mesotrophic soil and the other on a dystrophic soil, in central Brazil was compared. The concentrations of nutrients in the leaves of seven phytosociologically important species unique to each area and five species common to both areas were determined four times during a year. Species unique to the dystrophic soil showed lower concentrations of P, K, Ca, and Mg, and higher concentrations of N and Mn than species unique to the mesotrophic soil. Species common to both soils showed lower concentrations of Ca, Mg, and Mn in the dystrophic soil. Aluminum and Mn toxi‐cities may not be factors responsible for the exclusion of some species from the strongly acid dystrophic soil. On the other hand, high levels of Ca and Mn may be responsible for the exclusion of some species from the mesotrophic soil.

ISSN:0010-3624    

DOI:10.1080/00103628809367996

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Seedlings ofMiconia albicans(Sw.) Triana, an aluminum‐accumulating shrub, which grow naturally on acid latosols of the cerrado region of central Brazil, were grown in a strongly acid dystrophic soil, a strongly acid gallery forest soil and a calcareous soil in a pot culture experiment. The seedlings grew better in the fertile acid soil than in the dystrophic soil. They failed to grow in the calcareous soil, producing only a single pair of yellowed, necrotic leaves with low Al concentration after the emergence of a first pair of green leaves. Plants with chlo‐rotic leaves, transplanted from the calcareous to the acid soils, showed complete recovery of chlorotic leaves and a concomitant increase in the Al concentration in leaves.

ISSN:0010-3624    

DOI:10.1080/00103628809367997

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Acid soils and low fertility are commonly associated with forested lands in Canada. This study reports results from analyses of growth, and genetic heterozygosity (using isoenzymes) among three lodgepole (Pinus contortavarlatifolia) populations at different elevations along the foothills of Alberta and their associations with microsite variation among 17 soil traits. Means of 14 of the 17 traits were different (P<=0.05) among locations; 9 of the 14 exhibited clinal trends with elevation. The first of two significant (P<=0.001) discriminant functions (DF1, DF2) accounted for 80% of the multivariate variance among the three sites. DF1, a general “site quality” function, was weighted most heavily by soil reaction (pH) while DF2 was best described by zinc and phosphorous. Tree growth was positively related to DF2 in the low‐ and mid‐elevation populations. The frequencies of significant (0.01<P<0.10) associations between genetic heterozygosity and soils‐microsites decreased with increasing elevation; only significant (P<=0.05) negative correlations were found between heterozygosity and tree growth, all at the lowest elevation.

ISSN:0010-3624    

DOI:10.1080/00103628809367998

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effects of Ca and Al on shoot dry mass and total root length of two cultivars of soybean (Glycine max(L.) Merr.) were evaluated in a nutrient solution culture experiment. The experiment consisted of a factorial design comprising varying levels of Ca (ranging from 50 to 2500 μM), and Al (ranging from 0 to 588 μM). Relatively poor correlations were observed between measured plant growth parameters and individual monomeric Al species, this being ascribed to the interactive effect of Ca and Al. However, highly significant coefficients of determination were found where both Al and Ca activities were considered simultaneously. The best fit of the data was obtained when plant response was plotted against Calcium Aluminum Balance (CAB = [2log(Ca2+)] ‐ [3log(Al3+) + 2log(AlOH2+) + log(Al(OH)2+)]). Increasing Al levels in solution significantly depressed Ca, Mg, P and Mn concentrations in the shoots over all Ca treatments. There was no relationship observed between shoot concentration Al and the activities of Al3+, AlOH2+and Al(OH)2+. A highly significant relationship existed between Ca levels in the shoots and the derived CAB expression, indicating that the Ca content of soybean shoots is controlled by the interaction between Ca and Al monomeric species in solution.

ISSN:0010-3624    

DOI:10.1080/00103628809367999

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Aluminum toxicity is an important growth limiting factor for crop production on acid soils. The effect of five Al concentrations (0, 371, 742, 1484, and 2226 yM) in nutrient solution on the growth and chemical composition of six upland rice (Oryza SatiaL.) cultivars (IAC 1131, Fernandes, Matao, IPEACO 562, IRAT 2, and IPEACO 162) was studied. The concentrations and activities of Al species in the nutrient solution were calculated using the GEOCHEM program. The range in calculated activities of each of the Al monomers was 73 to 411 yM for Al , 7 to 41 μM for Al(OH)2+, 4 to 21 μM for AKOH)2+, 0.07 to 0.41 μM for Al(OH)3°, and 125 to 495 yM for AlSO4+. Aluminum reduced shoot and root growth but the magnitude of the reduction varied from cultivar to cultivar. The cultivar Fernandes was most tolerant and IPEACO 562 most susceptible to Al toxidty of those cultivars tested relative to shoot dry weight. Fernandes also had high P uptake and low Al concentration in the shoot compared to the other five cultivars. The uptake and use efficiency of P was more highly correlated with the growth of rice than the uptake or use efficiency of Ca or Mg.

ISSN:0010-3624    

DOI:10.1080/00103628809368000

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Soybean grown on high‐aluminum soil exhibits a marked inhibition of development of lateral branches of the shoot. This inhibition can be alleviated with exogenous cytokinin applications to the shoot. A primiry effect of aluminum is to restrict root meristematic development. Substantial evidence exists to show that the root meristem is a major site of cytokinin biosynthesis for transport to the developing shoot. The common locality of ytokinin synthesis and primary aluminum toxicity effects in the root meristems implies that limited cytokinin supply may inhibit lateral shoot development during aluminum toxicity stress. This is possibly due to a limitation in cytokinin‐induced meristematic development of the lateral shoots. In addition, the inhibition may involve altered calcium transport and cytokinin‐mediated distribution of calcium in these regions.

ISSN:0010-3624    

DOI:10.1080/00103628809368001

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

To investigate whether effects of Al in the sorghum genotypes SCO283 (Al‐tolerant) and NB9040 (Al‐sensitive) are primary effects of Al toxicity, a short‐term experiment was carried out. After 21 days of pregrowth in an Al‐free nutrient solution, plants were exposed to nutrient solutions without or with 10 mg 1‐1Al for 96 h. Nitrogen was supplied as NH4NO3. Twenty four h after Al supply, the relative uptake of all nutrient cations and anions, except NH4+, declined to values varying between 0.8 (K+) and 0.2 (Ca2+, Mg2+). In contrast, the uptake of NH4+was stimulated by Al in both sorghum lines. Total cation uptake and uptake of total nitrogen were balanced by the stimulation of NH4+uptake. As a consequence, excess cation uptake and proton efflux were increased by Al, especially in the Al‐sensitive line, NB9040.

ISSN:0010-3624    

DOI:10.1080/00103628809368002

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Plasma membrane‐enriched vesicles were isolated from maize roots, and pH‐induced changes of the physical state of the plasma membrane were monitored with a fluorescence probe, TMA‐DPH. At physiological temperatures, the membrane's microviscosity increased upon acidification of the vesicles’ suspending medium. It seemed that membrane protonation led to a reorganization of maize root plasma membranes. ATP‐dependent proton pumping activity across the vesicular membrane was assayed by quinacrine fluorescence quenching. By comparing the steady‐state level of pumping activity, the proton pumping activity at pH 6.5 was about three times that determined at pH 5.5. Proton pumping apparently originated in a plasma‐membrane bound Mg2+‐ATPase.

ISSN:0010-3624    

DOI:10.1080/00103628809368003

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor