摘要:

Silicon (Si) has been suggested as a factor in aluminum (Al) tolerance of some species of the gramineae when grown on acid soils. Silicon concentrations are generally much higher in monocot plants than in dicot plants, and the phenomenon is related to the fact that mineral cation:mineral anion uptake ratio is much higher in dicots than in monocots. When large amounts of anionic Si, supposedly as sulfate (SO44‐), participate in cation‐anion balance to add to the excess of anion uptake, equivalent amounts of hydroxyl ions should be expelled from roots which can increase rhizosphere pH and decrease uptake of Al and iron (Fe). The magnitude of OH−released by roots for a 5000 kg/ha crop with an excess uptake of 1% Si can be equivalent to 357 kg lime per hectare. This could be very significant in decreasing Al and Fe uptake from acid soils when localized in the rhizosphere. Success of agriculture on highly acid soils may be enhanced by use in a rotation of crops and cultivars that have the ability to accumulate Si.

ISSN:0190-4167    

DOI:10.1080/01904169209364401

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Stem nodulation, plant growth and nitrogen content were studied inSesbania rostratagrown at five different levels of fertilizer nitrogen. The number, fresh weight, and acetylene reduction activity (ARA) of stem nodules decreased with increasing nitrogen levels in the soil, while per cent nitrogen in the stem and leaf showed an increase.

ISSN:0190-4167    

DOI:10.1080/01904169209364402

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Plants of Norland potatoes (Solarium tuberosumL.) were maintained for 42 days at Mg concentrations of 0.05, 0.125, 0.25, 1, 2, and 4 mM in a non‐recirculating nutrient film system under controlled environment. With the increased Mg supply from 0.05 to 4 mM, Mg concentrations in the leaves of the 42‐day old plants increased significantly from 1.1 to 11.2 mg g‐1dry weight. Plant leaf area and plant and tuber dry weights increased with increased Mg concentrations up to 1 mM in solution or 6.7 mg g‐1in leaves, and then decreased with further increases in Mg concentrations. Rates of CO2assimilation measured on leaflets in situ at ambient and various intercellular CO2concentrations were consistently lower at 0.05 and 4 mM Mg than at other Mg treatments, which may indicate decreased photosynthetic activity in mesophyll tissues at the lowest and highest Mg concentrations. Dark respiration rates in leaves were highest at 0.05 and 4 mM Mg, lowest at 0.25 and 1 mM Mg, and intermediate at 0.125 and 2 mM Mg. The different Mg treatments also influenced accumulation of other minerals in leaves. Leaf concentrations of Ca and Mn decreased with increased Mg supply except that Ca and Mn were lower at 0.05 mM than at 0.125 mM Mg. Leaf K concentrations were lower at 1,2, and 4 mM Mg than at other Mg treatments. Foliar concentrations of P, Fe, Zn, and Cu had small but inconsistent variation with different Mg concentrations. Leaf concentrations of N, S, and B were similar at different Mg concentrations. This study demonstrates that various Mg nutrition, along with altered accumulation of other nutrients, could regulate dry matter production in potatoes by affecting not only leaf area but also leaf carbon dioxide assimilation and respiration.

ISSN:0190-4167    

DOI:10.1080/01904169209364403

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In vitro‐grownChrysanthemum morifoliumRamat. cultivars Bright Golden Anne, Deep Luv, and Lucido were exposed to elevated mannitol, sucrose, or sorbitol concentrations to see if their response to this osmotic stress mimics that ofin vivoplants enduring water deficit. The relative efficacy of the three osmotic agents at manifesting a response was also evaluated. Tissue osmolarity paralleled media mannitol and sorbitol concentration for all three cultivars. Shoot growth correspondingly decreased with increased osmolarity applied during the rooting phase. These responses generally resembled those of water‐stressed greenhouse plants. The degree of response varied with cultivar; ‘Lucido’ was the most sensitive and ‘Bright Golden Anne’ the least. Sucrose (metabolized by the plants)failed to elicit consistent osmotic stress symptoms; instead it enhanced both shoot and root growth.In vitrostress‐induced symptoms were produced in both proliferation and rooting stages, but consistent shoot growth reduction with increasing levels of incorporated osmotic agent was only observed during rooting. Plants did not retain the osmotic adjustment when they were subsequently subcultured from the stress treatments back to the control medium.

ISSN:0190-4167    

DOI:10.1080/01904169209364404

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The effect of N form (NH4or NO3) on Al toxicity was examined with 12 sorghum (Sorghum bicolor(L.) Moench) genotypes grown on nutrient solution (pH 4.2). The negative effect of Al on dry matter yield after two weeks of growth was increased by NH4‐N relative to NO3‐N in some genotypes and decreased in others. In contrast, the negative effect of Al on internal Mg concentration and specific root length (SRL; m per g dry root) was generally lowered by NH4,‐N. Moreover, the utilization of the Mg taken up seemed to be negatively affected by NH4‐N, as deduced from the occurrence of Mg deficiency symptoms. It was suggested that Al toxicity with the NO3‐grown plants was mainly expressed as root impairment (characterized by small SRL) and NH4‐induced changes in growth response of sorghum plants to Al were due to a shift of growth control towards Mg deficiency. The modification of Al toxicity on dry matter production of individual genotypes, induced by N form, might depend on their relative sensitivities to both Mg deficiency and root impairment.

ISSN:0190-4167    

DOI:10.1080/01904169209364405

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Effects of calcium (1, 2 and 5 mM) and aluminum (0, 15 and 45 μM) on growth and internal nutrient concentrations were examined with 12 sorghum genotypes (Sorghum bicolor(L.) Moench) in a nutrient solution experiment with a factorial design. At 1 (or 2) mM Ca the severity of root damage induced by Al well reflected the genotypical variation in growth response to Al toxicity. Severity of Al‐induced root damage slightly decreased with increasing Ca level. Moreover, Ca at 5 mM amplified the Mg deficiency induced by Al, as seen from both heavier deficiency symptoms and lower internal Mg concentrations. Under conditions of Al stress at a high Ca supply, induced Mg deficiency apparently predominated the genotypical differentiation in growth response to Al toxicity. An antagonism between Al‐ and Ca ions for uptake was hardly found with the sorghum genotypes. However, the genotypes differed in Ca efficiency, a characteristic which may be relevant in assessing their sensitivity to Mg deficiency.

ISSN:0190-4167    

DOI:10.1080/01904169209364406

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Excessive salinity can reduce growth of crop plants in many regions of the world but the underlying mechanisms are largely unknown. We investigated the possibility that inhibition of maize (Zea maysL.) leaf growth by salinity might be associated with loss of capacity to maintain adequate mineral nutrient concentrations in the leaf tissues. Maize plants were grown for 20d in a controlled environment on expanded vermiculite and irrigated daily with nutrient solution containing additional Ca. The effects of salinization with 100 mM NaCl and 20‐fold differences in the strength of the external nutrient solution on root growth, leaf growth, and ion concentrations in leaf tissues were determined. Salinity caused reductions in root and leaf growth. Increasing external nutrient supply to the roots increased growth of control plants but did not increase growth of salinized plants. Moreover, N and P concentrations in the leaf tissues were increased by salinity and Mg concentrations were unaffected. The small salinity induced reductions in concentrations of K and Ca ions, or lowered K/Na ratios, did not appear to be large enough to inhibit growth. Thus reduced leaf nutrient concentrations did not appear to be a primary cause of inhibited leaf growth under saline conditions.

ISSN:0190-4167    

DOI:10.1080/01904169209364407

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A field experiment was conducted at 2‐year interval to determine the optimum time, number of foliar sprays for applying water‐soluble iron fertilizers and chelates, and the relative efficiencies of four different sources of iron for recovery of groundnut (Arachis hypogaeaL.) plants from iron‐deficiency chlorosis for plants grown on a calcareous soil. Severe interveinal to complete leaf chlorosis was observed in 38–42% of the population during 30–60 days after emergence (DAE). Foliar applications of iron at 2 kg/ha in the form of 0.1% aqueous solution helped plants recover from chlorosis. However, no significant differences were found among the four iron sources [iron sulphate, iron sulphate+citric acid (400 g/ha), iron citrate, and Fe‐EDTA] with an average recovery of 46, 49, 47, and 46%, respectively. The maximum increase (16 to 24%) in pod yield was obtained when iron sulphate+citric acid was the iron source, while yield increases were 13 to 19, 12 to 18, and 11 to 18% over the control when iron sulphate, iron citrate, and Fe‐EDTA, respectively, were the iron sources. Splitting the application at a dose rate of 2 kg Fe/ha into two sprays at 1 kg each at 50 and 70 DAE, and in four sprays at 0.5 kg each at 30,45,60, and 75 DAE, gave the highest recovery of groundnut chlorosis, and produced the highest pod and haulm (fodder) yields.

ISSN:0190-4167    

DOI:10.1080/01904169209364408

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The ability of a hand‐held chlorophyll meter (SPAD‐502 Chlorophyll Meter3, Minolta Camera Co., Ltd., Japan) to determine the N status of cotton (Gossypium hirsutumL.) was studied at field sites in Alabama and Missouri. Meter readings on the uppermost fully‐expanded leaf were compared to leaf‐blade N and petiole NO3‐N at first square, first bloom and midbloom as to their seed cotton yield predictive capability. Nitrogen was applied at rates of 0, 45, 90, 135, 180 and 225 kg ha‐1to establish a range of cotton chlorophyll levels, tissue N concentrations, and seed cotton yields. A typical curvilinear cotton yield response to N fertilizer was observed in Alabama experiments.

ISSN:0190-4167    

DOI:10.1080/01904169209364409

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Evaluation of legume response to acidic conditions can be difficult when using nutrient solutions because of fluctuations in solution pH. The organic buffer 2(N‐morpholino)‐ethanesulfonic acid (MES) has been used for stabilizing pH in nutrient solution studies. We evaluated the effectiveness of MES (5.0 mM) to stabilize solution culture at pH 5.5 with and without mineral N (0 or 1.0 mMNH4NO3) and its influence on growth and N2fixation of arrowleaf clover(Trifolium vesiculosumSavi). The buffer maintained pH stability ± 0.1 pH units in the presence or absence of mineral N. In the absence of mineral N, the quantity of N2fixed by plants grown with MES was not significantly different from that fixed by plants grown without MES. However, with mineral N, N2fixation was reduced 37% with addition of MES. Tissue analysis indicated a small increase in Ca and Mg concentration for plants grown with MES. Caution should be exercised in the use of MES in studies of N2‐fixing legumes when mineral N is included.

ISSN:0190-4167    

DOI:10.1080/01904169209364410

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor