摘要:

Associations between vesicular‐arbuscular mycorrhizal (VAM) fungi and manganese (Mn) nutrition/toxicity are not clear. This study was conducted to determine the effects of excess levels of Mn on mineral nutrient uptake in shoots and roots of mycorrhizal (+VAM) and nonmycorrhizal (‐VAM) sorghum [Sorghum bicolor(L) Moench, cv. NB9040]. Plants colonized with and without two VAM isolates [Glomus intraradicesUT143–2 (UT143) andGl. etunicatumUT316A‐2 (UT316)] were grown in sand irrigated with nutrient solution at pH 4.8 containing 0, 270, 540, and 1080 μM of added Mn (as manganese chloride) above the basal solution (18 μM). Shoot and root dry matter followed the sequence of UT316 > UT143 > ‐VAM, and shoots had greater differences than roots. Shoot and root concentrations and contents of Mn, phosphorus (P), sulfur (S), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu) were determined. The +VAM plants generally had higher mineral nutrient concentrations and contents than ‐VAM plants, although ‐VAM plants had higher concentrations and contents of some minerals than +VAM plants at some Mn levels. Plants colonized with UT143 had higher concentrations of shoot P, Ca, Zn, and Cu and higher root Mg, Zn, and Cu than UT316 colonized plants, while UT316 colonized plants had higher shoot and root K concentrations than UT143 colonized plants. These results showed that VAM isolates differ in enhancement of mineral nutrient uptake by sorghum.

ISSN:0190-4167    

DOI:10.1080/01904169509364896

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The nitrogen (N) requirements of lettuce(Lactuca sativaL.) on a Spearwood sand were studied over two years, comparing N applied daily (6 to 12 times per day) by trickle fertigation (TD) with N broadcast weekly and sprinkler irrigated (SW). N was applied as ammonium nitrate (NH4NO3) at 0 to 550 kg/ha and water was applied at 100% or 150% of the previous day's pan evaporation (Epan A) to the TD and SW (two times per day) plots, respectively. Lettuce yield showed a significant response to N (P < 0.001) in both years. The TD plots were 21–42% (P < 0.01) more profitable than the SW plots. In Year 1, yield was significantly (P < 0.05) higher on the TD than the SW site. In Year 2, the interaction between irrigation/fertilisation treatment and N was significant (P < 0.05). Under TD, maximum yield (and profit) of 93 (Year 1) and 100 t/ha (Year 2) required 288 and 344 kg N/ha, respectively, while under SW, maximum yield of 86 and 93 t/ha required 230 and 321 kg N/ha, respectively. These rates of N are between 30 and 60% of those recommended for maximum yield of lettuce on coastal sands particularly on new land and would reduce the impact on groundwater pollution considerably. Agronomic nitrogen use efficiency (t yield + kg applied N both per ha) of lettuce under TD was 25% and 13% higher than under SW at 450 and 550 kg N/ha respectively. This was attributed to (i) less leaching of nitrate‐N, (ii) a more constant concentration of nitrate‐N over time, (iii) better placement of N, (iv) higher nitrate‐N:ammonium‐N, and (v) a lower than toxic concentration of ammonium‐N in the soil, under TD than under the SW treatment. The concentration of N in the wrapper leaves (WL) required for maximum yield at heading was 4.7% under both TD and SW treatments during the first Year and 4.7% for SW and 5.2% for the TD treatment in the second Year. Critical levels for maximum yield of % N in the WL tended to be higher under the more frequent application of N in the TD systems.

ISSN:0190-4167    

DOI:10.1080/01904169509364897

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Effect of sodium chloride (NaCl) on the growth, mineral concentration, and net accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) was established in one‐year‐old seedlings (Iberique, Landais, Tamjoute provenances) grown in a regulated greenhouse in nutrient solutions. Increasing concentration of NaCl induces a reduced rate of growth and the Iberique provenance was most affected. Accumulation of Na is significantly more intense in the Tamjoute provenance irrespective of the growth response. Macronutrient concentration are markedly modified, as a result of salinity, by increases in the N and K concentrations and decreases in P, Ca and Mg concentrations in the root. The nutrient concentrations in the tissues did not appear to become deficient or toxic under these saline conditions. Total accumulation of most ions was reduced as a consequence of relative growth and provide a good indication of geographic provenance response. The results presented here highlight the importance of Na/K ratio of maritime pine under saline conditions with respect to growth response. The Na/K criterion appears to be a relevant tool for the salinity tolerance estimation of maritime pine.

ISSN:0190-4167    

DOI:10.1080/01904169509364898

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A glasshouse study was undertaken to evaluate the effects of nitrogen (N) supply on the vegetative growth, yield components and the distribution of N in Linola™ (low linolenic acid linseed). Nitrogen stress reduced the number of tillers (secondary basal stems) and fruiting branches per plant. Severely N‐stressed plants produced only 20% of the dry matter of plants provided with an adequate N supply. The dry‐matter harvest index of the shoot was negatively related to N supply. The main effect of N stress on yield components was a reduction in the number of capsules per plant; seed number per capsule and the 1000‐seed weight were not altered by N stress. Nitrogen stress reduced seed and oil yields per plant through its effect on capsule production. Seed yield and seed oil percentage were reduced by excessively high levels of N supply. Concentrations of total N were highest in leaves and lowest in roots. There was little change in seed N concentrations in relation to N supply. Concentrations of nitrate‐N (NO3‐N) were higher in stems than leaves, and concentrations of both NO3‐N and total N decreased in vegetative organs as the plants aged, irrespective of N supply. There were biphasic relationships between concentrations of reduced N and NO3‐N in young plants. Leaves had the greatest proportion of the total amount of N in young plants, but seeds contained the major proportion in mature plants. Shoot N harvest indices ranged from 30 to 70%, and were inversely related to N supply. Depending on the N supply, plants accumulated from 57 to 76% of their final N content after flowering. Remobilization of N from senescing leaves ranged from 70 to 87%, and was highest for the most N‐stressed plants. Nitrogen remobilization from the leaf canopy was estimated to provide only about 10% of the N accumulated by seeds. It was concluded that an adequate supply of N is required throughout the growth of a Linola crop, in the pre‐ flowering phase to support tiller and fruiting branch production, and post‐flowering to sustain seed development.

ISSN:0190-4167    

DOI:10.1080/01904169509364899

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sorghum[Sorghum bicolor(L.) Moench. cv GP‐10] root tips (1‐cm) were exposed to45Ca2+for 1 hr. Root tips were washed in 0.01M EDTA for 5, 10, 15, 30, and 60 min. Calcium (45Ca2+) remaining in the roots decreased on a T1/2= 12–13 minutes scale, which represents Ca2+‐ATPase activity in the GP‐10 root tips (1‐cm).

ISSN:0190-4167    

DOI:10.1080/01904169509364900

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sorghum[Sorghum bicolor(L.) Moench. cv GP‐10] root tips (1‐cm) were exposed to potassium (K+) (1 mM), ruthenium red (RR) (0.1 mM), erythrosine B (EB) (1 μM), and combinations of K++ RR or K++ EB to measure calcium (45Ca2+) absorption in 1‐hr. K+ (1 mM) decreased45Ca2+absorption by 30%. RR (0.1 mM) decreased45Ca2+accumulation by 65%. EB (1 uM) induced a 35% decreased45Ca2+absorption. Addition of K+(1 mM) reversed the influence of RR and EB on45Ca2+uptake.

ISSN:0190-4167    

DOI:10.1080/01904169509364901

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of cadmium (Cd) on nitrogen (N2) fixing pea plants was studied. Perlite and vermiculite were compared as substrates in a hydroponic system where the plants were grown. In both experiments, there was no significant effect on nitrogenase activity when referred to fresh weight of nodules, but there was a reduction in the nodulation ratio (number of nodules developed per plant), even at low concentrations of available Cd. In plants grown in vermiculite, the nitrogenase activity expressed in terms of activity per nodule increased as Cd application increased; while in plants cultivated in perlite, that activity decreased when the applied Cd increased at the highest levels of Cd in the nutrient solution. Vermiculite had a significant interaction with the Cd in the nutrient solution, and therefore, we assume there was less Cd available to the plants than when perlite was used as the substrate. The loss of N2fixation by the presence of Cd in plants grown in perlite has been related to a change in the distribution of manganese (Mn) in the plant tissues. There was a reduction of Mn content both in the root and nodules. The reduction was greater in the nodules, while the concentration of Mn increased in the shoot.

ISSN:0190-4167    

DOI:10.1080/01904169509364902

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Rapeseed(Brassica napus)has been introduced recently in the pampean region, Argentina. Our objective was to assess the nutritional status of the crop under the usual relatively low nutrient supply of the area, aiming for a rational fertilization policy for this oil crop. Two cultivars were studied on a Vertic Argiudoll, at the experimental field of the Faculty of Agronomy, University of Buenos Aires. Plant samples were taken at the stages of rosette, elongation, flowering, and maturity. Dry matter and nitrogen (N), phosphorus (P), and potassium (K) contents were determined. Plant nutrient concentrations were within the range of plants grown under high nutrient supply, but the yields were low. The differences in growth rate did not means different total nutrient absorption. The seeds exported between 74 and 79% of the absorbed N and P, but K remained largely in the straw.

ISSN:0190-4167    

DOI:10.1080/01904169509364903

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Addition of L‐tryptophan (L‐TRP) to soil can have an ecological impact on the growth and development of some plants through its catabolism into auxins by rhizosphere microflora. A pot experiment was conducted to assess the influence of L‐TRP on growth and chemical composition of cotton(Gossypium hirsutumL.). Seven L‐TRP levels (10‐7to 10‐1g/kg soil) were applied as a soil drench in addition to a control. Data obtained revealed that specific growth parameters were significantly promoted, such as plant height (27.3%), dry weights of shoot (45.7%) and root (35.8%), biomass (43.3%), and number of branches (37.5%), flowers (63.3%) and bolls per plant (22.4%) in response to L‐TRP treatments. Similarly, the nitrogen (N), phosphorus (P), and potassium (K) concentrations in plant tissues and their uptake were also significantly affected by the exogenous application of L‐TRP. Significant linear or quadratic dose‐response relationships were found when root mass, branches, flowers, bolls, and NPK concentrations in plant tissues and their uptake, were regressed against log[L‐TRP] excluding the control. The effects of L‐TRP could be most likely attributed to its conversion into auxins by the rhizosphere microflora upon direct uptake by plant; however, other mechanisms such as direct uptake of L‐TRP by plant roots with subsequent auxin production within plant tissues or a change in the balance of rhizosphere microflora affecting plant growth cannot be excluded.

ISSN:0190-4167    

DOI:10.1080/01904169509364904

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Banding nitrogen (N) fertilizer increases inorganic N variability in areas between the corn rows for one or two years. Fertilizer recommendations may be improved by developing sampling systems that account for this variability. If soil samples are routinely taken from one location relative to another, then fertilizer recommendations may be biased. The objective of this study was to evaluate the impact of banding N fertilizer on N distribution in soil. Urea ammonium nitrate was applied to a Brandt silty clay loam (Fine‐silty, mixed Udic Haploboroll) at the six leaf growth stage in 1992. Soil samples were collected from grid points (0, 8,22, and >35 cm from fertilizer band) between the corn(Zea maysL.) rows in the fall of 1992. Soil samples were analyzed for inorganic N. In unfertilized plots, inorganic N distribution at all of the sampling locations followed lognormal distributions. However, in band fertilized plots inorganic N distributions were influenced by sampling location. Inorganic N estimated from samples collected 22 cm from the band underestimated residual N by 30 to 40%. Inorganic N was estimated correctly when samples were collected 8 cm from the band, while it was over estimated when samples were collected from the band.

ISSN:0190-4167    

DOI:10.1080/01904169509364905

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor