摘要:

The methodology given in this paper is designed to improve the cation nutrition ofCupressus glabra(Sudworth Little) growing on peat substrates for ornamental purposes. The methodology consists of studying the potassium/ calcium + magnesium (K/Ca+Mg) ratio first in sand cultures and then using the corresponding nutrient solution in the substrates. The interaction between the substrate and the nutrient solution is studied in the process. The analysis of the saturation extract of the substrate and the controlling the nutritional status of the plant by analysing its leaves and sap allowed for the establishment of the limiting growth factors for each substrate. Consequently, these factors can be corrected by adapting the nutrient solution. The methodology designed can be used with other conifers.

ISSN:0190-4167    

DOI:10.1080/01904169509364881

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Young maize(Zea maysL.) plants, grown hydroponically in a greenhouse, were leaf sprayed with MEIA (ß‐monomethyl ester of itaconic acid), MESA (monoethyl ester of succinic acid), and MEAdA (monoethyl ester of adipic acid) at concentration 1250 ppm when the 4th leaf was fully‐developed. The influence of these EDA (esters of dicarboxylic acid) on root/shoot ratio (RSR) and nitrogen (N), phosphorus (P), and potassium (K) concentration, accumulation and efficiency was investigated. MEIA did not change the RSR, but MESA and MEAdA decreased it. EDA in most cases increased N, P, and K concentration and accumulation in the leaves and total amount of these elements in the plants. On the contrary, MESA and MEAdA decreased or did not change content of the investigated nutrient elements in the roots. Nitrogen physiological efficiency was affected by EDA treatment.

ISSN:0190-4167    

DOI:10.1080/01904169509364882

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Soil and petiole nitrate‐nitrogen (NO3‐N) analyses have been used to monitor the nitrogen (N) nutritional status of cotton(Gossypium hirsutumL.) in Arkansas. The basis for in‐season N fertilizer additions has been NO3‐N monitoring for the most recently matured leaf petiole. In this manner N fertilizer can be adjusted so that N is not limiting during growing seasons conducive to high yields. The objective of studies reported herein was to determine petiole NO3‐N levels that define deficient, adequate, and excessive N nutritional status of irrigated cotton growing on a clayey soil. Experiments were conducted on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic, Vertic Haplaquept) located on the Northeast Research and Extension Center at Keiser, AR. The experimental design was a 5 by 5 Latin Square with a split plot arrangement of treatments. Subplots were cultivars of cotton, and main plots were N rates of 0, 56, 112, 168, and 224 kg/ha applied as 56 kg/ha splits beginning just before planting, again at pinhead square, and again at 56 or 110 kg/ha at early bloom until all N for a treatment was applied. The N fertilizer was 32% N solution (16% urea‐N and 16% ammonium nitrate‐N). Petioles were collected weekly beginning the week before first bloom and continued for eight weeks. Cotton was harvested and lint yield calculated. Subsequent analysis of petiole NO3‐N and lint yield were performed using (a)X2and (b) percent correct predictions on both the actual lint yield versus petiole NO3‐N content and the lint yield versus the slope of the petiole NO3‐N content with time. The results indicated that (a) the percent correct predictions were the best predictor, (b) petiole NO3‐N predicted lint yield losses from the week before first bloom until three weeks later at approximately 80% correct estimates and falls to 50% correct estimates for subsequent weeks, and (c) slope of NO3‐N with time gives percent correct estimates approximately 50% of the time. These results indicate that petiole NO3‐N content by itself is useful for determining the N nutritional status of cotton until the third week of bloom.

ISSN:0190-4167    

DOI:10.1080/01904169509364883

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The relationship between yield of dried clover herbage(Trifolium subterraneum)and the level of phosphorus (P) applied (yield response to P) was studied in the year of application for two successive years at two sites and five successive years at one site. Single superphosphate and two rock phosphates were compared at each site. Data for the relationship were adequately described by a Mitscherlich equation. At each site, for each fertilizer, the yield response to P was different in different years, with both the maximum yield plateau and the shape of the relationship differing between years. Expressing yield as a percentage of the maximum (relative) yield reduced the variations so that only the shape of the relationship, described by the exponent (curvature) coefficient of the Mitscheriich equation, differed between years. This is attributed to the effect of different seasonal conditions on the yield responses of clover herbage to freshly‐applied P. The value of the curvature coefficient was related to rainfall for five successive years at one site. The following trends were observed: (i) for superphosphate, the value of the coefficient tended to decrease with increasing rainfall so that more P was required to produce the same relative yield; and (ii) for rock phosphate, the value of the coefficient tended to increase with increasing rainfall so that less P was required to produce the same relative yield.

ISSN:0190-4167    

DOI:10.1080/01904169509364884

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Lime‐induced chlorosis still today places limits on cultivation and optimum production of many fruit tree species, even in only slightly calcareous soil. Research must, therefore, be directed towards new selections of rootstocks and/or cultivars tolerant of this abnormal soil condition. In addition, it is necessary to evaluate the possibility of adopting physiological parameters, such as root cation exchange capacity (CEC) for a rapid screening of new selections. This physiological indicator, when used together with other evaluation parameters, such as vigor, clorophyll and mineral content, allowed to obtain a reliable identification of the most tolerant rootstocks. The aim of the present work was, therefore, to assess whether this parameter can discriminate among Myrobalan clones and GF 677 rootstock as regards iron (Fe) efficiency. This method is based on the assumption that the root system is the plant component playing the most fundamental role in allowing Fe utilization.

ISSN:0190-4167    

DOI:10.1080/01904169509364885

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

“MA”; quince clonal rootstock is more susceptible to lime‐induced chlorosis than clone “Ct.S.212”;. Trials were performed in order to determine whether differences observed between the two clones in calcareous soil were maintained when iron (Fe)‐deficiency was induced by addition of bicarbonate (HCO3) to a modified Hoagland nutrient solution No 1. In addition, trials were aimed to verify whether the rootstocks showed differing physiological responses. Results confirmed that total leaf Fe content was not a suitable tool to screen rootstocks for chlorosis tolerance. In contrast, “active”; Fe and chlorophyll content (well correlated with chlorotic symptom levels), together with fresh and dry matter production, were found to be good parameters for genotype evaluation. Total Fe content increased in the root system of stress‐grown “MA”; plants more than in “Ct.S.212”; root systems. Root Fe3+‐reductase activity increased in “MA”; and “Ct.S.212”; under Fe‐deficiency conditions obtained by using an Fe‐free solution or by addition of sodium bicarbonate (10 mM NaHHCO3). In this case, “Ct.S.212”; showed roughly 6‐fold increased capacity three hours after the beginning of the assay. This increase was greater than that induced by Fe absence. Clone “MA”; showed similar behaviour, but with a lower rate of reduction (3‐fold increase in reducing capacity).

ISSN:0190-4167    

DOI:10.1080/01904169509364886

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two quince rootstocks for pear, clones “MA”; and “Ct.S.212”;, were screened under iron (Fe)‐limiting conditions inin vitroculture. The most important objectives of this work were: first, to develop use of the tissue culture technique as a rapid screening methodology for evaluation of Fe efficiency in quince, and second, to identify morphophysiological characters associated with variation in response. Iron content of the MS medium (200 meq FeEDTA) was reduced to 80%, 65%, 50%, 25%, and 15% of standard content in order to induce chlorosis symptoms. Results showed that “Ct.S.212”; presented a higher proliferation rate and greater growth than clone “MA”; in the 15 and 25% Fe treatments, but clear symptoms of chlorosis were observed in both clones at the two lowest Fe concentrations. Parameters of vegetative development commonly used inin vitroculture proved to be difficult to interpret for this type of screening, and further tests will be necessary. In contrast, type and content of chlorophyll were shown to be an indicative test, although not completely reliable.

ISSN:0190-4167    

DOI:10.1080/01904169509364887

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Soil samples of 50 g clay, clay loam and sandy loam were amended with ammonium sulphate giving 25, 50, 100, 200, and 400 mg nitrogen (N)/kg and with two nitrification inhibitors, Dicyandiamide (DCD) and N‐Serve (N‐S) each at two levels calculated relative to the N applied, 1 and 5%, and 0.5 and 1%, respectively. Water was added to moisture field capacity and the samples were incubated at 30°C for 7, 14, 28, and 56 days, each treatment and timing in three replicates. The lower level of application of nitrification inhibitors was not effective. Nitrate‐N (NO3‐N) recovery peaked at 28 days and did not change appreciably later, except the 1% N‐S treatments where a flush of NO3appeared at the 56th sampling day. The nitrification inhibitory effects of the two inhibitors were enhanced at the 200 and 400 mg/kg ammonium‐N (NH4‐N) application in all three soils. Nitrification inhibition was not related to salt concentrations as measured by electrical conductivity.

ISSN:0190-4167    

DOI:10.1080/01904169509364888

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Different cultivars of grape plants were used in these experiments. They included 3‐month‐old plants obtained by a method of clonal micro‐reproduction, seedlings grown in pots from 2‐budded cuttings, and perennial fruit‐bearing bushes used in vineyards. Iron (Fe) concentration in grape plants varied depending on tissue, varieties, stage of vegetative growth, condition of the plants, growing conditions, etc. Iron deficiency resulted in chlorosis and Fe content decreased in leaves from plants growing in an artificial nutrient medium. As chlorosis progressed in severity, it resulted in a decrease in Fe content in the leaves and annual shoots. This might be connected with premature senescence of plants and Fe efflux into perennial tissue in spite of its relatively low mobility in plants. Foliar supplement with Fe‐containing compounds to chlorotic plants increased the Fe content of leaves and improved the general health of the plants.

ISSN:0190-4167    

DOI:10.1080/01904169509364889

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

To examine plant physiological responses to salinity, waterlogging, and subsequent drainage, summer squash(Cucurbita pepo)was grown in well watered or flooded sand with full‐strength Hoagland solution containing 100 mol/m3sodium chloride (NaCl) or no NaCl for 14 d. Half of the waterlogged plants were transferred to drained conditions for 7 d of recovery, while half of salinized plants were continuously salinized until 21 d. Waterlogging or salinity alone reduced photosynthetic rate (Pn), stomatal conductance (gs), and leaf chlorophyll content to a greater extent with waterlogging. Waterlogging alone, however, did not affect leaf water potential (ψ leaf) Salinity alone did not affect leaf and root nitrogen content. A combination of waterlogging and salinity exacerbated the adverse effects of each factor alone for Pn, gs, leaf chlorophyll, and nitrogen content, but not for ψ leaf. Seven days after termination of waterlogging, a full recovery occurred for gs, ψ leaf, leaf chlorophyll content, and leaf and root nitrogen content for waterlogged plants under non‐saline conditions, while for waterlogged plants under saline conditions those parameters did not achieve that of the control value.

ISSN:0190-4167    

DOI:10.1080/01904169509364890

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor