摘要:

AbstractStarch and amylose content in conventional and semi‐leafless cultivars of garden and field peasSmall‐plot experiments were carried out with conventional and semi‐foliated cultivars of garden and field peas (Pisum sativum, ssp.medulareandssp. sativum) to investigate the effect of increasing potassium dressings on starch, amylose and sugars in mature seeds during two years.Field peas compared with garden peas produced: (1) 2 times higher seed yields, (2) 1.6 times higher starch contents (41–44 % DM), (3) nearly comparable amylose contents (17 % DM), (4) 3 times higher amylopec‐tin contents (26 % DM), (5) 4 times lower sugar contents (1.6 % DM).In the presently existing cultivars field peas are by far superior to garden peas with regard to amylose production per area. Compared with conventional cultivars the semi‐leafless types of both subspecies yielded the same seed weights, and they differed in no respect in the seed components analysed.Improved potassium nutrition increased yields of seeds and straw, but had no significant effect on the seed componen

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00770.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractFour soybean genotypes chosen from four seed sources were planted in a factorial arrangement on four dates in a split‐plot design at the Alabama A&M Experimental Station on a Decatur silt clay loam soil. The highest vigor index was recorded from seeds harvested from the 4th date of planting. These seeds had the lowest level ofDiaporthe phaseolorumvar.caulivorainfection, indicating that vigor index, as a measurement of seed quality, was negatively correlated with the level of infection by soybean stem canker pathogen. Seed yield was highest at the 2nd date of planting and lowest at the 4th date of planting. Tracy‐M and Bedford confirmed previous reports on their resistance and susceptibility, respectively, to soybean stem canker. All the genotypes performed their best at the 2nd date of planting. Source of seeds appeared to have little effect on the performance of the plant in the fi

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00771.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractTrial in a farmer's holding, which was sandy containing 80‐90 per cent of fine and coarse sand fraction, was conducted to evaluate the effect of ten successive rollings by 400 kg stone roller (1 meter width) on the soil physical properties and yield of groundnut (var. TMV 3). By rolling, the bulk density was increased from 1.50 g/cc to 1.63 g/cc in the 20‐30 cm layer; Hydraulic conductivity was reduced from 36.7 cm/h to 17.3 cm/ h in the same subsoil layer (53 per cent over control) which resulted in higher moisture retension capacity of the soil, the increase being 51.5 per cent over control in the 30‐40 cm layer. The final dry pod yield increase was 19 per cent over control. The effect of compaction was seen at the post‐harvest soils also, in that the increase in bulk density, decrease in hydraulic conductivity were observed. The variations were more effective at 10‐20

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00772.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractBased on measurements in 3 different types of soil (clay, sand, peat) linear regression equations between daily air temperature (2 m) and soil temperature (2, 5, 10, 20, 50 cm depth) are calculated for all months of the growing season. The equations show a significant seasonal dependence and the best correlations in the upper 10 cm of soil. Differences depending on the type of soil are relatively small. Correction terms involving cloudiness and thermal inertia of the soil during a sudden warming or cooling period complete the prediction model. Standard deviations between predicted and measured values have been found within 1.5 K in most cases. Lastly a generally applicable method for calculating regression equations at any station is introduced. The application of this method to different sites and types of soil in Bavaria and other regions of Germany shows a good agreement with measured values.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00773.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractEffects of cultivar (wheat) and species (wheat, rye) mixtures on grain yield of desease‐free standsCultivar mixtures (winter wheat) and species mixtures (winter wheat/winter rye) grown free from pests and diseases in different environments are compared to pure stands and analyzed with respect to inter‐component relationships relevant for yield. All mixtures consisted from two components which were planted 1:1. Mixing effects (i.e. deviations from arithmetic mean of respective components grown in pure stands) on grain yield/ha and yield structure were dependent on components and growing conditions, particularly nitrogen availability. Under conditions suboptimal for one component, ontogenetic differences between components resulted in positive mixing effects on grain yield since the yield proportion of the accompanying partner increased more than proportionally. In several instances, yield proportions shitted without leading to mixing effects. In some experiments and/or mixtures mixing effects could not be observed at

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00774.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractField bean planes cultivar Nadwiślański were submitted to soil drought (30 % of field soil water capacity) for 5 days at the stage of pod formation (A) and of rapid pod growth (B) and then exposed for 20 minutes to14CO2. Radioactivity of leaves, stems, roots, and pods or pod shells and seeds was measured 1, 5, 24 and 48 hours after exposition.In both stages soil drought reduced by about five times total CO2assimilation, mainly owing to lower activity of the photosynthetic apparatus and also, though less so, to reduced leaf growth. Photosynthetic activity referred to the dry weight of the leaves dropped to 22‐35% of controls. Accumulation of photosynthetates in generative organs was much less depressed than14CO2assimilation. 48 hours after exposition to14CO2of drought treated plants, the contents of14C of pods in phase A, and seeds in phase B, amounted to respectively 24% and 36% of assimilated14C and equalled 91.5% and 74% of the corresponding values for controls.The progressive decline of radioactivity in leaves and stems after14CO2exposition was distinctly correlated to the rise of radioactivity of generative organs both in soil drought treated plants and in controls. Slightly lower values of correlation coefficients in drought treated plants may indicate impairment under drought conditions of synchronization in processes of unloading and accumulation of assimilates.In plants drought treated in phase A the ability to dissimilate14C was reduced to about 59% of that in controls, but when drought was applied in phase B, dissimilation rate was about three times as h

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00775.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractGrowth and ionic relations of red kidney bean plants were compared when grown in 25, 50 and 75 mM concentrations of either NaCl or KCl salts. Similar growth reductions of plants at 25 mM concentration of the two solutions were observed as compared with control solution grown plants. Whereas relatively higher growth reductions indicated by reduced relative growth rates in 50 and 75 mM KC1 solution as compared with isosmotic NaCl solutions were associated with higher Cl and K uptake and accumulation in leaves. This was confirmed by higher short‐term36Cl uptake/transport in plant leaves from the labelled solution of 50 mM KCl as compared with that from 50 mM NaCl solutio

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00776.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAutomatic distinction of weed species using form parameters by means of digital image processingIn former investigations the possibility to distinguish weed from soil background by computerized quantitative image analysis has been reported. In the present studies image analysis technique are applied to identify different weed species. From six typical winter weed species including various growth stages, 300 color slides were taken at the research station in Bonn on the 4th of February, 1988. From each slide a number of form parameters were measured automatically out of the digitized shape of each weed plant. Form parameters including area, perimeter, minimum and maximum diameter of the plants are taken from the digitized shape of each weed as well as figures representing the relative proportions of these parameters. For automatic discrimination up to 9 of the parameters were selected to compute five so‐called canonical variables. The values of these variables are typical for each weed species and can be interpreted as their “finger prints”. The average rate of correct identification was 82.3 %. The scientific and practical implications of the results are disc

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractWinter wheat growing on a silty clay loam soil was protected from rainfall by a mobile shelter for 100 days from tillering to maturity. During this time the crop was either irrigated according to demand or grew on stored soil water. The effects of this high and low water supply, in combination with a high and low N supply, on root and shoot growth and water uptake were studied.The crop given both N and water yielded 9.7 t/ha of grain (85 % DM), drought reduced this to 7.9 t/ha, low N to 4.3 t/ha and drought and low N to 3.8 t/ha. Yield reductions were mainly due to fewer grains being produced.Little root growth occurred in the topsoil during the drought but there was compensatory growth in the subsoil provided that N fertilizer was given. The droughted crops rooted to 160 cm, about 20 cm deeper than the irrigated crops, but the amount of root in the deep subsoil was very small, less than 0.1 cm/cm3ai 140–160 cm, compared with 5–9 cm/cm3in the topsoil.The crop demand for water at any given time was partitioned throughout the root system but atmospheric demand was only met whilst the topsoil was wet. The fertilized, droughted crop extracted all of the potentially available water to a depth of 80 cm and a mean rooting density of 1 cm/cm3was necessary to achieve this. Uptake from below this depth was limited by root growth.The limiting value of the potential soil water deficit was 170 mm, and weather records showed that this would be exceeded one year in ten, on average. The likelihood of yield reduction due to drought could be reduced on this soil by improving root growth below 80 cm depth, although the chances of achieving this are low as root growth was probably limited by poor soil struct

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY