摘要:

A study was undertaken to evaluate the yield, fruit size, and vegetative growth of three strawberry cultivars inoculated with three vesicular‐arbuscular mycorrhizal (VAM) species at three phosphorus (P) fertility levels. Vesicular‐arbuscular mycorrhiza inoculation and P fertility had no effect on inflorescence or flower number, total yield, fruit weight, or crown number. Higher levels of P did not increased total dry shoot weight, total fresh shoot, weight leaf area, total dry root weight, and leaf number in the present of VAM. However, the cultivars responded differently to VAM inoculation. Vesicular‐ arbuscular mycorrhiza inoculation in combination with P at all levels increased total dry and fresh shoot weight, leaf area, and leaf number compared to application of P alone. The results indicated that it may be possible to increase strawberry stolon production by inoculating the strawberry plants with VAM, a technique which might be useful in nurseries to produce certified strawberry plants.

ISSN:0190-4167    

DOI:10.1080/01904169509364963

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

More information on the response of newly developed or introduced grain sorghum cultivare to split‐applied nitrogen (N) in semi‐arid rainfed agriculture is needed. Therefore, the influence of four split‐applied N schedules (100/0, 66/34, 50/50, and 34/66) on six American (SC 283, SC 274, SC 669, B 66181, SC 33, and RTam 428), and four West African (CSm 63, 1S 6704c, 1S 7173c, and 1S 7419c) grain sorghum cultivars was evaluated. The split‐applied N significantly increased grain yield and percent protein in grain sorghum over a one‐time application of N. The increase in yield and protein content varied among varieties and schedules of N application. Varieties SC 574, RTam 428, and Csm 63 at split‐applied schedules of 66/34, 50/50, and 34/66, respectively, gave the highest yield over one‐time application of N. Similar differences in percent protein in grain among cultivars due to split‐applied N were observed.

ISSN:0190-4167    

DOI:10.1080/01904169509364964

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An experiment was conducted to study the effects of polyethylene glycol (PEG) on citrus growth and mineral composition. Seedlings of 7 citrus rootstock cultivars were treated with three osmotic potential levels (‐0.10, ‐0.20, and ‐0.35 MPa) of PEG for five months under greenhouse conditions. Increasing the concentration of PEG in the nutrient solution proportionally reduced root and shoot growth in all rootstocks. Although roots were in direct contact with PEG, their growth was less affected by PEG treatments than that of shoots. Seedling growth was reduced the most in Carrizo citrange and Milam lemon. Significant differences in root and leaf mineral concentrations among cultivars were found under PEG stressed and non stressed conditions. Furthermore, no consistent relationship in mineral absorption, translocation and accumulation seemed to exist between citrus roots and leaves. Root and leaf mineral concentrations were also significantly altered by PEG in all rootstock cultivars. Nitrogen (N), potassium (K), and magnesium (Mg) were reduced in the leaves and calcium (Ca) was reduced in the roots but zinc (Zn) and manganese (Mn) were noticeably increased in the roots. The results of this study demonstrated that some of the deleterious effects of PEG could be attributed to nutritional imbalances, N and Mg deficiency in the leaves and Zn and Mn toxicity in the roots of citrus cultivars.

ISSN:0190-4167    

DOI:10.1080/01904169509364965

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Previous research showed that applying fertilizer phosphorus (P) to the soil in concentrated subsurface bands increased P availability to crops compared to a surface application. Early growth responses of corn (Zea maysL.) plants were measured after 28 days of growth in pots in a greenhouse for single band, two single bands, injection, and surface fertilizer P placement methods. Fertilizer P was applied at the rates of 0, 12, and 24 mg P/kg soil for each method for three different soils. Shoot dry matter weight and nitrogen (N) and P uptake increased for all placement methods regardless of initial soil test P level. However, growth parameters were greater for the banded and injection methods. Response parameters were minimally influenced by the surface P application, but some fertilizer P from the surface application leached through small desiccation cracks after daily additions of water. This probably increased P availability slightly. Shoot dry matter production efficiency and shoot N/P ratio were higher for the surface P placement method and for the unfertilized P treatments. Overall growth responses to fertilizer P rates were less effective in soils with higher initial soil test P levels.

ISSN:0190-4167    

DOI:10.1080/01904169509364966

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ten‐day‐old seedlings of rice (Oryza sativaL., varieties c.v. (Nona bokra, Basmati, IR28, and IR29) grown on MS medium were used in this study. Total protein extract from roots of control and 2% salt‐treated plants were analyzed by two dimensional electrophoresis. Following eight hours of salt stress including terminal three hours ofin vivolabeling, two new proteins of molecular weights corresponding to 27 and 25.5 kD were detected. These proteins were not detectable with silver staining after one day of stress but became evident after two days of salt treatment and gradually increased up to four days. During recovery after two days of treatment, their levels decreased gradually and were present even after two days of recovery, though, in decreased amounts. No such protein was induced in plants stressed with copper (Cu), cadmium (Cd), heat, ABA, or PEG treatments. Quantitative changes in the amount of other proteins were also observed. This indicates that the rice plant may adjust to the changes in its ionic environment by altering its macromolecular composition of root tissue.

ISSN:0190-4167    

DOI:10.1080/01904169509364967

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of vanadium (V) on the vegetative development and nitrogen (N) metabolism inPhaseolus vulgarisL. was studied. The plants were grown in hydroponic conditions (vermiculite). The control plants received 0.1 μM molybdenum (Mo); the treated plants (V lot) also received 80 μM V. The V supply favoured root development ofP. vulgarisand it led to dry weight accumulation in shoots and roots. Results of nitrate, nitrite, ammonium, and total nitrogen (N) of V‐treated plants were not statistically different from those of the control plants. The results suggest that V treatment was not detrimental toP. vulgaris, at least when the V supply was administered during the vegetative development of the species.

ISSN:0190-4167    

DOI:10.1080/01904169509364968

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect that different levels of molybdenum (11 μMand 111 μM) exert on nitrate reductase (E.C. 1.6.6.1–3) activity (NRA), and the content of total proteins inNicotiana rusticawas studied. Eleven μM and 111 μM of molybdenum increased the activity of nitrate reductase during the growth cycle ofN. rustica. Likewise, total protein content (mg/g DW) was increased during the vegetative growth of the plants.

ISSN:0190-4167    

DOI:10.1080/01904169509364969

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In a field experiment with wheat(Triticum aestivumL.), the effect of the percentage severity oftake‐allon the production of dried tops and grain and the kernel weight (mg/seed) was measured when different amounts of phosphorus (P) fertiliser were applied. The soil was severely P deficient. The amounts of P fertitiser varied from nil P (deficient) to 40 kg P/ha (adequate) applied annually. The levels ofGaeumannomyces graminis tritici(Ggt) were generated by four cropping sequences. The levels of percent severity of Ggt on plant roots ranged from low (<10% of wheat plant roots infected) to high (70% of roots infected by Ggt). Yield of dried tops, grain, and kernal weight, all increased as the level of P applied increased, but the amount of Ggt infection decreased. No grain was produced where no P was applied. The percentage increase in yield due to declines in the severity oftake‐allwas greater as the level of P applied increased. Increasing levels of P fertiliser help control the severity of Ggt (%) only where the initial level of Ggt with nil P fertiliser are moderate to low. Where the levels of Ggt severity are >65% the effectiveness of P in reducing the levels of Ggt severity rapidly declined. The percentage severity of Ggt affected the efficiency of plants to use P fertilisers. For each cropping sequence, a Mitscherlich function described the grain yield response to P fertiliser. The maximum grain yield (A coefficient) and the curvature coefficient (C) both declined with increases in the level of Ggt severity (%). For example, the C was significantly reduced from 0.134±0.03 for the least Ggt severity (%) to 0.00446±0.001 where Ggt was not controlled. The kernal weight (mg/seed) was increased by P application and decreased by Ggt infection.

ISSN:0190-4167    

DOI:10.1080/01904169509364970

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

When grown with mixtures of nitrate‐nitrogen (NO3‐N) and ammonium‐nitrogen (NH4‐N) (mixed N) spring wheat (Triticum aestivumL.) plants develop higher order tillers and produce more grain than when grown with only NO3. Because similar work is lacking for winter wheat, the objective of this study was to examine the effect of N form on tillering, nutrient acquisition, partitioning, and yield of winter wheat. Plants of three cultivars were grown to maturity hydroponically with nutrient solutions containing N as either all NO3, all NH4, or an equal mixture of both forms. At maturity, plants were harvested; separated into shoots, roots, and grain; and each part analyzed for dry matter and chemical composition. While the three cultivars varied in all parameters, mixed N plants always produced more tillers (by a range of 16 to 35%), accumulated more N (28 to 61%), phosphorus (P) (22 to 80%), and potassium (K) (11 to 89%) and produced more grain (33 to 60%) than those grown with either form alone. Although mixed N‐induced yield increases were mainly the result of an increase in grain bearing tillers, there was cultivar specific variation in individual yield components (i.e., tiller number, kernels per tiller, and kernel weight) which responded to N form. The presence of NH4(either alone or in the mixed N treatment), increased the concentration of reduced N in the shoots, roots, and grain of all cultivars. The effect of NH4in either treatment on the concentrations of P and K was variable and depended on the cultivar and plant part. In most cases, partitioning of dry matter, P, and K to the root decreased when NH4was present, while partitioning of N was relatively unaffected. Changes in partitioning between the shoot and grain were affected by N treatment, but varied according to cultivar. Based on these data, the changes in partitioning induced by NH4and the additional macronutrient accumulation with mixed N are at least partially responsible for mixed‐N‐induced increases in tillering and yield of winter wheat.

ISSN:0190-4167    

DOI:10.1080/01904169509364971

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sour orange (Citrus aurantiumL.) seedlings were grown for 3 months in diethylenetriamine pentaacetate (DTPA)‐buffered nutrient solutions to study the effect of Zn stress on the plants’ sensitivity to high boron concentration in the root environment. There were three zinc treatments: 21 μM Zn (LOW Zn‐DTPA), 69 μM Zn (NORMAL Zn‐DTPA) in the nutrient solution, or 12 weekly foliar sprays with ZnSO4(FOLIAR‐Zn). In the FOLIAR‐Zn treatment, the nutrient solution contained 21 μM Zn. Zn activities calculated with a chemical equilibrium model, Geochem PC, and expressed as pZn=‐log(Zn+2), were 10.2 and 9.7 in the LOW Zn‐DTPA and NORMAL Zn‐DTPA nutrient solutions, respectively. One half of the plants in each Zn treatment were grown in 51 μM B (NORMAL‐B) and the other half in 200 μM B (HIGH‐B) nutrient solution. Seedlings grown in LOW Zn‐DTPA/NORMAL‐B nutrient solution developed Zn deficiency symptoms such as: reduced shoot growth, small and chlorotic leaves, and white roots with visibly shorter and thicker laterals than in Zn sufficient plants. The HIGH‐B treatment decreased shoot growth, leaf and stem dry weight, leaf area, and induced severe leaf B toxicity on seedlings grown in the LOW Zn‐DTPA nutrient solution but the effect was either absent or less pronounced in the NORMAL Zn‐DTPA or FOLIAR‐Zn treatments. Seedlings in the LOW Zn‐DTPA FOLIAR‐Zn treatments but they had lower B concentration on a whole plant basis indicating less B uptake per unit of dry weight. The FOLIAR‐Zn and NORMAL Zn‐DTPA treatments were equally effective in alleviating leaf B toxicity symptoms. The FOLIAR‐Zn treatment, however, was less effective than the NORMAL Zn‐DTPA treatment in alleviating the deleterious effect of high B on leaf dry weight even though the B concentrations in leaves, stems, and roots of the foliar‐sprayed seedlings were similar to the NORMAL Zn‐DTPA seedlings. Leaf concentrations of phosphorus, potassium, magnesium, iron, mangenese, and copper were within the optimal range for citrus with the exception of Ca which was low. Although B and particularly Zn treatments modified the concentration of some of these elements in leaves and roots, these changes were too small to explain the observed growth responses. The observation that B toxicity symptoms in Zn‐deficient citrus could be mitigated with Zn applications is of potential practical importance as B toxicity and Zn deficiency are simultaneously encountered in some soils of semiarid zones.

ISSN:0190-4167    

DOI:10.1080/01904169509364972

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor