摘要:

AbstractChanges of clay soils under organic and conventional farmingChemical, mineralogical and soil‐physical measurements were performed on clay soils, which were cultivated under conventional and organical production system for the last 14 years. Soils in the organic system [TNL soils] were loosened from 10–35 cm and organic residues and manure were incorporated into the 0–10 cm layer by a rotowator. Soils in the conventional system [TKL soils]were plowed to a depth of 22 cm. Humus and nitrogen reserve and the amount of mobile phosphate in the top soils of the TNL soils were higher than in those of the TKL soils. The exchangeable potassium in the top soil was higher in TKL soils than in TNL soils, whereas the organic system (TNL) showed a more equal distribution within top and subsoil. This observation was confirmed by measurements of the mobile potassium (ARo‐values).The contents of 2:1 layer silicates with expanded layers was lower in the top soil of TKL soils than in TNL soils. This can be explained by the reduced application of liquid manure (Gülle) and the missing application of potassium fertilizer on TNL soils. The layer charge of the expanded minerals ranged from ‐0.80 to ‐0.68 for the vermiculites, and from ‐0.45 to ‐0.35 for the smectites, per formula unit respectively.No influence on the percentage of the fine and mid pores was found. The amount of slow draining large pores (Ø 50‐10 μm) was higher in TNL soils than in TKL soils, only in a neighbouring pasture soil the proportion of these pore exceeded those of TNL soils. Measurements of pore continuity did not show such a clear difference between TKL and TNL soils, but was

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00710.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractTime‐course and varietal expression of freezing resistance (FR) in relation to environmental conditions as well as agronomic performance of winter faba beans were investigated during 5 winter seasons in Northern Germany. Sowing of 6 or 9 European populations was done at a rate of 33 seeds/m2during September and October. FR was assessed from the lowest two leaves of the plants which were detached and subsequently subjected to artificial freezing tests.Maxima of mean FR ranged between ‐12 and ‐15°C in different years. A comparison of the considerable oscillations of mean FR during single seasons, with environmental data gave evidence that (1) a reasonable level of FR (i.e.‐12°C) was initially achieved about 4 to 10 weeks after sowing depending on the temperature prevailing at plant emergence. (2) The increases in FR were associated with cool temperatures (daily min. ∼ ‐5/+5 and max. ‐0/+10°C), and the decreases with warm temperatures (daily mean ≥+10°C). (3) Furthermore, long periods of severe frosts or temperatures fluctuating around 0° and/or freeze‐drying by east winds considerably weakened FR and caused substantial leaf necroses. Varietal rank pattern in FR (Cote ď Or>Hiverna, NP, Webo>Avrissot, Survoy>Banner, Bourdon, Bulldog) generally changed only slightly during as well as between midwinters. Only twice, (i) after a long frosty period and rehardening temperatures and (ii) when dehardening in spring has already advanced considerably, this pattern was completely changed.Agronomic performance of 6 populations was examined in dependence of 3 sowing times at 3 locations in 4 years. While generally 80–95 % of seeds emerged within 2 to 4 weeks and developed 2 to 3 leaves/plant until cessation of growth in winter, the small seeded populations (Avrissot, Cote ďOr) emerged 1 to 2 weeks later. Plant emergence was slightly favored on location I (humic sand), but considerably delayed and reduced by late sowing (mid Oct.), Winter survival ranged between 0 and 100 % and was strongly affected by years and to a lesser extent by locations and populations. A clearcut effect of the sowing time was established only once (the later, the better the survival).Results were compared with each other and to those under controlled environments and were discussed with respect to their agronomic implications and

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00711.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAllelopathic effects of aqueous extract of three weeds,Ageratum conyzoidesL.,Imperata cylindrica(L.) Beauv andCommelina benghalensisL. of Nigerian savanna were investigated on the germination and seedling vigour of soybean (Glycine max[L.] Merr.) and maize (Zea maysL.). Aqueous extracts of these weeds exhibited allelopathic phenomenon on seed germination and seedling vigour. Aqueous extracts ofI. cylindricaand C.benghalensisat 1 % and 5 % concentration (w/v) had stimulatory effect on soybean germination as against inhibitory effect of 10 % aqueous extract of all weeds on the germination of both soybean and maize seeds. Seedling vigour‐length of roots and shoots and fresh weight of seedlings were promoted by aqueous extract ofA. conyzoidesup to 5 % concentration in soybean whereas all concentrations of extract stimulated the seedling vigour of maize. Aqueous extract ofI. cylindricaup to 5 % also caused stimulatory effect on the seedling vigour of both crops but such effects were lesser in magnitude than that observed in case ofA. conyzoides.On the contrary, the aqueous extract ofC. benghalensisat all concentrations resulted in deleterious effect on the seedling vigour of both soybean and maiz

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00712.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of 10‐day periods of soil drought during flowering (DI) or pod growth (DII) and during both these phases (DI + DII) on leaf water status, photosynthesis rate, plant growth and production of biomass was studied in pot experiments with field bean. Soil water content during drought spells were kept at 30% of field water capacity. Soil water deficiency DI and DII depressed the leaf water potential relatively to control by about 100 % and 140 % respectively, increased the water deficit by 100 % and 120 % and reduced photosynthesis rate by 80 % and 90 %. Rehydration of tissues completely abolished any decline of photosynthesis rate caused by drought DI, but after drought DII photosynthesis rate remained depressed by about 30 % even after rehydration. Drought periods DI and DII caused more rapid withering of leaves, a decline in the total leaf area and a temporary increase of root weight.Drought occuring at flowering (DI) also activated the mechanism of plant adaptation to water deficiency during the pod formation phase (DII). Single or double periods of drought had not any significant influence on the number of pods and seeds, but decreased their weigh

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00713.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractField trials were conducted for two years on two farms which differed in long‐term application of pig slurry in order to study the effects of long‐term organic manuring, timing of slurry application (no slurry, slurry autumn, slurry spring) and additional doses of mineral N‐fertilizer (0, 80, 160, 240 kg N/ha) on growth and quality of sugar beet.The results can be summarized as follows:1. The effect of slurry application on growth of sugar beets varied markedly with the long‐term differences in farm management. On the “arable farm” yield of beet roots increased substantially after slurry application and could not be replaced by higher doses of mineral N fertilizer. It is concluded therefore that “special effects” of farmyard manure are involved. On the “livestock farm”, however, highest beet yields were obtained on plots without slurry. Additionally slurry application caused a significant decrease in beet yields.2. Sugar beets without slurry treatment always developed higher sugar contents and lower concentrations of alpha‐amino‐N, sodium and potassium as compared to beets from plots with slurry application.3. Despite the decline in sugar content, sugar yield greatly increased by slurry application on the “arable farm”. The average increase in sugar yield was 10 dt/ha (=8%) with slurry application in autumn and amounted to 16 dt/ha (=14%) with spring application. On the livestock farm however, additional applications of slurry caused a decline in sugar yields in both years because of lower sugar contents and decrease in beet yields.4. The utilization rate of slurry‐N, depending mainly on time of application, annual rainfall and soil N mineralization, varied from 6–41%. On the “livestock farm” the utilization of slurry‐N was only half of the rate obtained on the “arable farm”.5. The application of small doses of slurry may cause a significant yield increase on farms without or only less livestock, while on farms with intensive livestock production continous slurry application needs to be considered as an expensive form of waste disposal. Therefore farms with high livestock density are advised to sell slurry to neighbouring farms without or only low animal production a

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00714.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPlant spacing study has been conducted on two types of Roselle, namelyHibiscus sabdariffavar.Masri, andH. sabdariffavar.Sudani.The two types are traditionally used to be cultivated in Egypt in loamy rich soils at a distance of 60 to 70 cm between hills. In the present experiment, however, they were cultivated in a newly reclamed desert land. The spacing treatments were 30, 50 and 70 cm between hills. The results revealed that the wider spacing (70 cm) resulted in shorter plants with more branches and higher number of fruits per plant. However, the narrower spacing (30 cm) gave higher weight of fruits, fresh sepals and accordingly, higher yields of dry sepals, anthocyanins and acids compared with the treatment of 70 cm. The best results concerning the yield of sepals and active constituents per unit area were gained when Roselle plants were planted at 50 cm spacing. The spacing treatments did not affect the content of anthocyanins or total acidity as a percentage.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00715.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe dry matter accumulation and photosynthetic traits of upper leaves were studied twice weekly in 1983, under field conditions, for two early maturing maize cultivars. Analysis of correlation between climatic data and those traits were based on four week periods. Seasonal patterns of correlation coefficients were drawn by shifting the beginning of these four week periods from one sampling data to the next until four weeks before the end of the sampling period. Most traits were significantly correlated with climatic factors at one time or another; only those correlations which were of longer duration will be mentioned here. Net assimilation rate was positively correlated with maximum temperature during intensive leaf growth. The relative growth rate was closely correlated with photosynthetic photon irradiance (PPI) during the second half of June and with phosphofructokinase activity during the second part of July. The chlorophyll content showed a close and positive relationship with minimum temperature until the end of June and with PPI during most of August. The content of carotenoids was, for the most part, negatively correlated with climatic factors, the closest relationship existing with the PPI at the previous sampling date until the beginning of July. The activity of photosynthetic enzymes such as RuBP carboxylase, NADP malate dehydrogenase and PEP carboxylase was generally less closely correlated with climatic factors over longer periods. Patterns of correlation were remarkably similar for the two cultivars.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00716.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractImpact of crop rotation, fertilizer treatments and herbicidal applications on the long term maintenance of soil fertilityV. Comparative studies regarding chemical and physical factors of the yield potential of a soil over a ten year experimental periodIn order to examine the influence of different crop management practices such as crop rotation, fertilizer treatments and herbicide applications on the yield potential of a soil, the Crop Science Department of the Swiss Federal Institute of Technology (ETH Zurich) conducted a long term field experiment commencing 1973. The experimental location was at the Swiss Federal Research Station for Farm Management and Agricultural Engeneering at Tanikon/TG (northeastern Switzerland).After the ten year period, chemical and physical soil properties were not found to be substantially affected by the various experimental treatments. Organic carbon and total nitrogen were more influenced by fertilizer treatments than by crop rotation and herbicide applications. Both cation exchange capacity and pH proved to be fairly stable values.Aggregate stability and organic matter exhibited similar profiles, although soil bulk density was affected by crop rotation. The volume of large and medium sized pores was similarly affected in that the corn‐dominated crop rotation resulted in a quantifiable impact upon soil compaction.Depending upon weed control efficiency, the grain yields of the winter wheat test crop clearly exhibited the effects of crop rotation whereas the lowest yields resulted from the corn‐dominated crop rotat

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Books Reviewed in this Article:International Rice Research Institute (IRRI). Genetic Manipulation in CropsBán, L: Biomathematics and its Applications in Plant CultivationKlimek, S., und M. Zoschke: Neuere Ergebnisse der Ackerbohnenforschung in Polen.Jones, M. B., and A. Lazenby (Eds.): The grass crop – The physiological basis of productionWissenschaftliches Festkolloquium zum 90jährigen Jubiläum der Biologischen Bundesanstalt für Land‐ und ForstwirtschaftElmadfa, I., und C. Leitzmann: Ernährung des Menschen.Hille, M.: Erhebung über Art und Menge der während des Erntejahres 1987 in verschiedenen Ackerbaukulturen angewendeten Wirkstoffe von PflanzenschutzmittelnLieth, H. H. F., und B.A. Markert. Aufstellung und Auswertung ökosystemarer Element‐ Konzentrations‐Kataster; Eine Einführung.Böhm, W.: Göttinger Pflanzenbauwissenschaftler. Eine BibliographicBakker, M. J., and W. M. Williams (Eds.). White Clover.Klingmüller, W. (Ed.)‐ Risk assessment for deliberate releases.46. Deutsche Pflanzenschutz‐Tagung in Regen

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY