bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effectiveness of Vernalization of Immature Embryos of Winter Wheat var. Grana as Related to Age and Exogenous Phytohormones
Authors: Dubert F. , Marcińska I. , Biesaga‐Kościelniak J. , Szmider I.
Published: April 2008

Starting from the 10th day after pollination, immature embryos of winter wheat var. Grana were isolated and then vernalized for 4 to 8 weeks on Murashige and Skoog nutrients containing BAP (0.5 or 2 mg/dm3), NAA (0.5 or 2 mg/dm3), or GA3 (5 or 20 mg/dm3). Vernalized seedlings were cultivated in a greenhouse and the number of days to the heading of individual plants as well as the percentage of plants capable of generative development were estimated.

The lower limit of size for 50 % survival of embryos strongly depended on the phytohormone used: from 0.9 mm in control, 1.1 mm in nutrient containing BAP, 1.2 mm for NAA, up to 1.7 mm in nutrient with GA3.

Exogenous GA3 was lethal for embryos younger than 18 days but induced elongation of older embryos.

Embryos isolated 2.5 to 4 weeks after pollination showed minimal requirements for the length of vernalization.

BAP increased the percentage of heading plants originated from the youngest embryos.

GA3 improved partial vernalization, strongly increasing the percentage of heading plants, but did not change the time from the end of vernalization to heading. It has been postulated that GA3 increases number of plants capable of overcoming the threshold of induction of generative development but does not accelerate the flowering process.

Hormonized plants showed no deformation of generative development. As the effectiveness of vernalization increased, the heading of plants was faster but they were shorter, forming spikes with a smaller number of spikelets and producing fever lateral shoots.

The very young embryos probably have in reserve sufficient amounts of auxins and gibberellins and therefore exogenous GA3 decreases their viability or even exerts a deleterious effect. However, as the embryos' ageing, gibberellin starvation develops. This being especially pronounced during vernalization.

The de novo synthesis or activation of gibberellins takes place during the second stage of vernalization. This is why exogenous hormone improves the effectiveness of partial vernalization, though it is not possible to substitute by gibberellins the vernalization requirements of immature embryos.
Effect of Water Shortage on Main Shoot Development and Tillering of Common and Spelt Wheat
Authors: Cabeza C. , Kin A. , Ledent J. F.
Published: April 2008

Water stress was imposed by cessation of watering (CW) on bread wheats and, in some experiments two spelt wheats, during 9–17 days, starting at the 4–5 leaves stage. Main shoot foliar stages (MSS) were delayed by CW and the effect remained thereafter.

The presence of side tillers (intact or partly destroyed by heat or potassium iodide (KI) was not beneficial to main shoot foliar development after the end of CW. Emergence of tillers after the onset of CW was also delayed, but the effect was small if timing was expressed in MSS. Secondary tillers were the most sensitive to water shortage, their number, size and foliar stage were drastically reduced.

The two cultivars of spelt wheats were not less sensitive to CW than the bread wheat tested.
Fruiting Efficiency in three Bread Wheat (Tritkum aestivum) Cultivars Released at Different Eras. Number of Grains per Spike and Grain Weight
Authors: Slafer G. A. , Miralles D. J.
Published: April 2008

Increasing sink size (i.e. number of grains m−2) has been the way of the genetic improvement for obtaining higher grain yield of wheat. We have studied under field conditions the number of fertile florets and grains per spike and individual grain weight of three bread wheat cultivars (Klein Favorito, Eureka FCS and Buck Pucara) which were previously selected to represent cultivars released at different eras (1920, 1940 and 1980, respectively) in Argentina (Slafer and Andrade 1989).

The three cultivars Buck Pucara, Eureke FCS, and Klein Favorito averaged 56.9, 48, and 34.5 grains spike−1. Differences were observed in both main shoot and tiller spikes. The number of fertile florets at anthesis was greater in the modern cultivar than in the other two cultivars; however, the intermediate and old cultivars did not significantly differ in this trait. Differences in number of florets and number of grains spike were independent of the number of spikelets spike−1; spikelet numbers did not vary among the three cultivars. Therefore, both the number of fertile florets produced per spikelet and the ability of the cultivar to set grains in those florets were responsible for the different number of grains spike−1 among cultivars. The modern, high yielding cultivar had a lower individual grain weight than the old, low yielding cultivar when the average of all grains were considered; but basal grains of its central spikelets were as heavy as those of the other cultivars.

We suggest (i) that the modern cultivars of Argentina have increased their ability both to produce fertile florets and to set grains, and (ii) that the lower individual grain weight of the modern cultivars does not imply an increased competition for resources as a consequence of their higher number of grains.
Effect of Agronomic Factors on Annual Leguminous Forage Crop in Mediterranean Environments
Authors: Martiniello P. , Ciola A.
Published: April 2008

Dry matter and seed production of five annual leguminous species hairy vetch (Vicia villosa Roth cv. Orsara), crimson clover (Trifolium incarnatum L. ecotype Campano), squarrosum clover (T. squarrosum L. ecotype Calabro), persian clover (T. resupinatum cv. Accadia) and fenugreek (Trigonella foenum‐graecum L. ecotype Maltese) was estimated in 1989–90 under two density and irrigation rates and with two cutting treatments. The experiments were done at the Forage Crops Institute of Foggia, which has a typical Mediterranean environment. The forage cut severely affected the regrowth of the plants in all species. The year and irrigation factors affect dry matter, seed production and seed yield components more than the plant density rates. The averages over the years, for dry matter and seed yield were 21.0 % and 20.5 % higher in the irrigated than the not irrigated ones. The lower plant density rate, for seed yield trait, gave better result in hairy vetch in irrigated and non‐irrigated treatment. Whereas in the other species, the lower rate of planting gave greater yield under non‐irrigated and the higher rate under irrigated growing condition. The seed yield components most influenced by irrigation were: thousand seed weight and seeds/pod in hairy vetch and heads/tiller and seeds/head in clovers species. Fenugreek was the earliest forage crop (cut at the beginning of March), followed by crimson and persian clovers (cut at the middle of April) and squarrosum clover and hairy vetch (cut in the middle‐late of May). All the cultivars and ecotypes considered not regrowth after cut and could represent an important fresh forage resource for the period March–May for the Mediterranean regions.
Effect of the Russian Wheat Aphid on the Composition and Synthesis of Water Soluble Proteins in Resistant and Susceptible Wheat
Authors: van der Westhuizen A. J. , Botha F. C.
Published: April 2008

The effect of Russian wheat aphid (Diuraphis noxia) infestation on polypeptide composition and protein synthesis in the presence or absence of chloramphenicol and cycloheximide were studied in genetically comparable wheat (Triticum aestvum) resistant (cv. PI 137739/5* Tugela) and susceptible (cv. Tugela) to the aphid. The aim is to gain information of molecular nature on the resistance phenomenon which may promote future breeding programmes. In the absence of feeding aphids polypeptide profiles of the two wheat lines were similar indicating the absence or presence at low levels of a constitutive resistance factor. Aphid infestation induced enhanced expression of certain genes in the resistant wheat only. A 100 kD nuclear encoded polypeptide is strongly induced in the resistant wheat. It is also evident that the synthesis of a 56 kD organel encoded polypeptide is suppressed by the feeding aphids in the susceptible wheat.
High Protein Soybean Performance Under Field Conditions
Authors: Ma B. L. , Leibovitch S. , Voldeng H. D. , Smith D. L.
Published: April 2008

An early maturing soybean [Glycine max (L.) Merr.] cultivar has been developed with substantially higher seed protein concentration than previously available cultivars. The objectives of this study were to evaluate the performance of the high protein line under field conditions in Eastern Canada, and to investigate the interrelationships between protein and oil concentrations, seed weight and yield. A field experiment, including the high protein line OT89‐16 and its recurrent backcross parent Maple Arrow grown side by side, was conducted at McGill University, during 1990 and 1991. The protein concentration of OT89‐16 was 17 % greater than that of Maple Arrow for both years. However, the protein yield of OT89‐16 was not significantly increased, the oil content was 19 to 23 % lower, and oil yield per ha was over 30 % lower than those of Maple Arrow. The lower yield of OT89‐16 was closely associated with its lighter seeds. Further efforts to improve the high protein line should attempt to maintain the same high protein levels but achieve yield equal to that of the parent line through selection for heavier seeds.
Model for Slurry and Manure in CERES and Similar Models
Authors: Hoffmann F. , Ritchie J. T.
Published: April 2008

Proceeding from the structures and hypotheses of the CERES and SALUS models a model for considering manures has been developed. The model includes the following processes: infiltration during application, ammonia volatilization, leaching of ammonium and organic bound nitrogen and mineralization before incorporation, incorporation, ammonia volatilization, mineralization and leaching of organic bound nitrogen after incorporation. With the CERES Maize model combined with the manure model simulations were calculated concerning the following problems:

– influence of application time of slurry on nitrate leaching under German site conditions and

– influence of long‐term slurry fertilization and of stopping slurry fertilization on organic N content, mineralization, uptake by maize and leaching under Southern Michigan site conditions.

Results and conclusions are presented.
The Relationship Between Sugar‐Nitrogen Ratio and Reproductive Organs Abscission in Faba Bean (Vicia Faba L.)
Authors: Xia M. Z.
Published: April 2008

The changes of soluble sugar and total nitrogen content of vegetative organs in faba bean, sugar‐nitrogen ratio, abscission of reproductive organs and the relationship between sugar‐nitrogen ratio and abscission probability were studied using the faba bean cultivar Xichang Dabai. Plants were field grown in 1986, 1988 and 1990. The lands were separated into high yield land, middling yield land and low yield land according to grain yield at maturing stage. The soluble sugar content in vegetative organs (leaf + stem) was greatest from branching to floral initiation stages and pod‐set to filling grain stages, and distinctly decreased at the onset of bloom and maturing stages. The total N content was greatest at branching stage, and gradually decreased with growth. In general, the sugar and total N contents in high yield lands were greatest, followed by that in middling yield and low yield lands. The sugar‐nitrogen ratio varied depending on the soluble sugar content.

Average yield on high yield lands, middling yield land and low yield land across 3 years were 5048.77 kg/ha, 3744.01 kg/ha and 2378.22 kg/ha, respectively. The total reproductive organs abscission exceeded 90 % of total flower buds. Abscission probability averaged across 3 yield lands and 3 years were 21.6 %, 84.0 % and 32.8 % in flower buds, flowers, and pods, respectively. Node 7–12 of canopy produced more flowers, and fewer flowers and pods were produced in the upper and lower regions. Photosynthate supply has been implicated in control of abscission. Faba bean reproductive organs abscission probability increased with the sugar‐nitrogen ratio of vegetative organs decreasing. It seemed that the soluble sugar content influenced significantly the shedding rate during flowering and pod‐growing stages.
Soil Temperature Simulation with Varying Residue Management
Authors: Brar G. S. , Unger P. W.
Published: April 2008

Maintaining crop residue on the soil surface is an important part of conservation tillage. Although broad effects of residues on soil temperature (Ts) are well documented, the methods to predict soil temperatures under various surface residues and tillage conditions are limited. Using the Ts at 0‐, 0.05‐, 0.10‐, and 0.30‐m depths, we developed a simplified model to predict Ts for a uniform soil from air temperature (Ta) data. Data were collected under various tillage and surface residue conditions after wheat (Triticum aestivum L.) harvest. Residue management treatments were disk, sweep, and no‐tillage (with standing or shredded residues). The model predicts maximum and minimum Ts at 0‐, 0.05‐, 0.10‐, and 0.30‐m depths using maximum and minimum Ts measured at 2‐m above the soil surface, residue mass, apparent thermal diffusivity, and initial Ts profiles. Mean absolute deviation between simulated and measured maximum and minimum surface Ts were 0.53 and 0.44 °C or less, respectively. Root zone maximum and minimum T, were simulated within 0.14 to 0.91 and 0.27 to 0.95 °C, respectively, of the measured Ts. Greater precision of maximum and minimum soil temperature predictions with depth was obtained by using apparent thermal diffusivity calculated from initial Ts profiles. The proposed model can be useful in predicting Ts profiles required for crop growth modeling.
Changes in Leaf Water Relations and Injuries in Maize Seedlings Induced by Different Chilling Conditions
Authors: JANOWIAK F. , Markowski A.
Published: April 2008

The time course of injuries and electrolyte leakage as well as changes in leaf water content and relative turgidity during chilling at 5°C, 65 or 100 % relative humidity (RH) were determined for seedlings of two maize hybrids differing in chilling tolerance.

In the course of chilling of entire seedlings the statistically significant injuries and increased leakage of electrolytes occurred first, followed by significant water deficit in leaves which was independent of RH and genotype. However, during prolonged chilling high and significant correlation between the level of chilling‐induced water stress and the extent of injuries was observed. Thus it has been assumed that the main factor responsible for primary chilling injuries in maize seedlings is the immediate influence of chilling temperatures on the cell membranes, and not the secondary water stress. The level of the water stress and the extent of the dehydration injuries under chilling conditions depended on the chilling sensitivity of the genotype. Differences between the examined genotypes consisted not only in delayed chilling injuries in a chilling tolerant hybrid, but also in significantly lesser effects of these injures on water relations.

However, exposure to low temperature of the aboveground part or of the roots of the seedlings only, caused first the chilling‐induced marked water deficit in the leaves and next increased leakage of electrolytes. A direct effect of chilling temperature on the membranes in a situation when only a part of the seedling is being chilled, may be less harmful to the plant as a whole owing to normal functioning of the non‐chilled part.
Effect of Completion of Vernalization on Generative Development of Winter Rape (Brassica napus L. var. oleifera) Plants
Authors: Filek W. , Dubert F.
Published: April 2008

Germinating seeds and young plants of winter rape var. Górczañski were vernalized for 56–63 days under conditions of 9‐hour day, at the temperature 2 and 5 °C and in continuous darkness at the temperature 2 °C. After vernalization the plants grew under conditions enabling to complete vernalization: in a glass‐house at the temperature day/night 15/10 °C and in semi natural conditions of open vegetation hall in the period from June till August. After sub‐optimal vernalization further growth of the plants at lowered temperature increased its effectiveness (completion of vernalization). Depending on the degree of the vernalization of the plants the completion of their vernalization was both obligatory, i.e. conditioning the acquisition of the ability of generative development, and facultative i.e. accelerating this development. It has been demonstrated that the population of plants of the examined variety is strongly differentiated not only with respect of vernalization requirements in the particular plants, but also what regards the effectiveness of vernalization completion. New observations have been made indicating that the mechanisms controlling the successive phases of generative development, i.e. phase of forming flower buds and the flowering phase are not identical which may be interpreted as indicating that the “flowering factor” is polymorphous.
Growth, Yield and Nodule Activity of Phaseolus vulgaris L. as Affected by Soil Moisture
Authors: Sangakkara U. R.
Published: April 2008

A study evaluated the response of two varieties of beans (Phaseolus vulgaris L.) to different soil moisture levels during a dry season. The soil moisture regimes maintained throughout the growth period were field capacity, 70–75 %, 50–55 % or 20–25 % available soil moisture.

Plant growth, yield and nodulation were optimal when plants grew at high soil moisture levels. With increasing stress, all measured parameters of both varieties were reduced. However, polebeans, with its vine type of growth was affected to a greater degree than bushbeans. In contrast, nodulation and nodule activity of both variables was affected by moisture stress.

A second experiment evaluated the effects of different soil moisture levels over the growth cycle of bushbeans, which produce greater yields under drier conditions. The highest yields were obtained at higher moisture levels throughout the growth cycle. Moisture stress up to flowering reduced yields to a greater extent than when the plants were subjected to reduced soil moisture after flowering appearance. Some casual mechanisms of the results of the experiments and possible implications for incorporating this popular vegetable legume in rainfed agricultural systems are presented.
Nitrogen Fertilizer and Protein, Lipid, and Non‐structural Carbohydrate Concentrations During the Course of Maize Kernel Filling
Authors: Zhang Feng , Mackenzie A. F. , Smith D. L.
Published: April 2008

A field experiment was carried out at four location‐years in Southwestern Quebec, Canada in 1990 and 1991, to evaluate the effects of nitrogen (N) application on protein, lipid, non‐structural carbohydrate (NSC), and remaining grain components concentrations of maize (Zea mays L.) grain during kernel development. Three N fertilizers (ammonium nitrate, urea, and calcium ammonium nitrate) were compared for plants receiving pre‐plant incorporated N fertilizer at 180 kg ha‐1 as well as a control which received no N fertilizer. The results indicated that between 20 and 30 days after pollination (DAP) protein concentration of maize kernels declined sharply, thereafter only slightly, irrespective of the treatment. At most stages and in all four location‐years protein concentration was raised significantly by N‐application without clear difference between N‐fertilizer sources. At 20 DAP seeds of N‐fertilized plants contain 25.5 mg g‐1 more than those without N‐application (control); later on, this difference was lower (12.8 mg g‐1) but remained constant over time if averaged over N‐sources and location‐years. At most growth stages and in most location‐years the lipid concentration did not respond to N fertilizer application. Lipid concentration followed an “N” shaped curve over the course of grain development. Non‐structural carbohydrate (NSC) concentration increased significantly during grain filling and showed little effect due to N application. However, at most growth stages in the four location‐years, the concentration of remaining grain components tended to decline with N application. A significant negative correlation existed between the changes in protein concentration and NSC concentration during kernel development.
Some Effects of Soil Salinity on Growth, Development and Yield of Rapeseed (Brassica napus L.)
Authors: Boem F. H. Gutierrez , Scheiner J. D. , Lavado R. S.
Published: April 2008

The effects of increasing soil‐salt levels on emergence, shoot and root growth and yield composition of rapeseed were investigated. A range of electrical conductivity (EC) values in the soil solution from 2.3 dS m‐1 to 10.3 dS m‐1 was obtained by adding NaCl to the substrate. The emergence was significantly (P < 0.05) decreased at EC values higher than 6 dS m‐1 Above this value, a delay in the appearance of leaves and of the first visible internode was observed. The further increase of salinity level extended the period for siliqua formation and grain filling, and plant height, pod number and grain number per plant were lowered. However, the cultivar used showed the ability of counterbalancing for this lower grain number by increasing the seed weight, thus there were no variations on seed yield. The seed oil and protein content were also not affected by the changes in salinity. Root growth was adversely affected when salinity levels exceeded 6 dS m‐1. Beyond this value, short tuber‐like roots became remarkably frequent. This may be an adaptation mechanism of this species to saline stress; a similar reaction in rapeseed is known in adaptation to drought stress.
Nitrogen, Phosphorus and Potassium Concentrations in Developing Maize Grains
Authors: Alfoldi Z. , Pinter L. , Feil B.
Published: April 2008

A 2‐year (1989, 1990) experiment was conducted in the Carpathian Basin near Keszthely, Hungary to evaluate the course of nitrogen (N), phosphorus (P) and potassium (K) concentrations in the developing grain. Two maize hybrids were grown at four rates of N application (0, 50, 150 and 250 kg N ha‐1). Plots had been fertilized at these levels since 1983. As a result of the long‐term N treatments, stocks of P and K in the soil decreased as the rate of N application increased. As expected, concentrations of N in the mature grains were higher at high doses of N, whereas the rate of N application had little impact on the P and K concentrations in the ripe grains. Only in 1989, when grain yield showed a relatively stronger response to applications of N than in 1990, were the concentrations of P and, to a lesser extent, K reduced by additions of N. These results illustrate that P and K concentrations in the grain are well‐buffered against increments in grain yield resulting from the application of N and are also relatively insensitive to low supplies of P and K in the soil. In both hybrids, concentrations of N, P and especially K declined considerably with ongoing grain filling, irrespective of N treatment. Differences in concentrations of P and K for hybrids existed but were not consistent across years.
Lodging and Yield of Dry Peas (Pisum sativum L.) as Influenced by Various Mixing Ratios of a Conventional and a Semi‐Leafless Cultivar
Authors: Schouls J. , Langelaan J. G.
Published: April 2008

Lodging is a serious problem in dry pea production in North‐West Europe. Therefore, lodging and its effects on yields were studied in five field‐experiments with two cultivars with two different canopy structures, both as single crop and in various mixing weight ratios. In 1985, mechanically simulated lodging decreased yield by about 45% in both the conventional type cv. Rondo and the semi‐leafless type cv. Solara, by reducing both the number of seeds and seed weight. Natural lodging brought about the same effect in ‘Rondo’ but in ‘Solara’, however, effects were less because of delayed lodging. In 1986, 1987 and 1988, mixtures of the conventional cv. Finale and Solara showed delayed lodging compared to ‘Finale’ single and tended to produce higher yields than the single crops of both cultivars. Polynomial analysis of the yields of all mixing experiments showed maximum yields at 53%‘Solara’ (quadratic analysis) or 67%‘Solara’ (cubic analysis). Thus, mixing high yielding, lodging sensitive conventional cultivars with lower yielding but lodging resistant semi‐leafless cultivars may improve yield in dry peas.
Crop Response to Improved Drainage of Vertisols in the Ethiopian Highlands
Authors: Abebe M. , Mamo T. , Duffera M. , Kidanu S. Y.
Published: April 2008

The effect of flat seedbed, traditional ridge and furrow and improved drainage of broad bed and furrow (BBF) on grain and straw yield of durum wheat, chickpea and lentil at several Vertisol sites between 1988—1991 was such that on three crops the BBF system gave the highest grain and straw yields at all locations and seasons. This was followed by traditional ridge and furrow system and the least yield was obtained from flat seed beds. The extent of drainage influence on yield was dependent on rainfall quantity, location (clay content) and crop species. The advantages of the BBF technology in improving drainage and increasing crop yield are discussed in their contexts of better cropping systems.
Foliar Nutrient Analyses in Bananas Grown in the Highlands of East Africa
Authors: Wortmann C. S. , Bosch C. H. , Mukandala L.
Published: April 2008

Data gathered from 45 farms in the Kagera Region of Tanzania were used to estimate critical nutrient levels (CNL) of foliar tissue and norms of the Diagnosis and Recommendation Integrated System (DRIS) for bananas (Musa spp.) grown in the highlands of East Africa.

CNL values are proposed as 3.1 % N, 1.13 % Ca, 0.48 % Mg, 18.4 ppm Zn and 10.0 ppm B. Optimum ranges for cation ratios were estimated as 0.54—0.67 for K/(K + Ca + Mg), 0.22—0.32 for Ca/(K + Ca + Mg) and 0.09—0.15 for Mg/(K + Ca + Mg). Productivity of bananas and foliar levels of P, K, S, Fe, Mn and Cu were too weakly related to estimate CNLs for these nutrients. A set of DRIS norms for East African Highland bananas is presented.
Performance of Sugarcane (Saccharum officinarum L.) Under Surface Drip, Sub Surface Drip (Biwall) and Furrow Methods of Irrigation
Authors: RAMESH P. , KAILASAM C. , SRINIVASAN T. R.
Published: April 2008

Field experiments were conducted at the Sugarcane Breeding Institute, Coimbatore, India during 1989–93 to study the productivity and water use efficiency of sugarcane under different methods of irrigation. The results showed that there could be a 44 % saving in water with higher water use efficiency in drip irrigation compared to conventional furrow irrigation. Among drip irrigation systems in the plant crop, sub surface drip (Biwall) at 40/140 cm spacing recorded a significantly higher number of millable canes, cane length and single cane weight compared to either conventional furrow irrigation or furrow irrigation based on IW/CPE (Irrigation Water Cumulative Pan Evaporation) ratio. In ratoon crop, Biwall irrigation at 60/120 cm gave significantly higher cane length and single cane weight compared to any other methods of irrigation. However, cane and sugar yields in Biwall irrigations were on par with conventional furrow irrigation but superior to either surface drip or furrow irrigation based in IW/CPE ratio.
The Influence of Johnsongrass Infestation and Nitrogen Rates on Grain Sorghum
Authors: Kegode G. O. , Bishnoi U. R. , Mays D. A.
Published: April 2008

Gram sorghum [Sorghum bicolor (L.) Moench] is grown on marginal land and johnsongrass [Sorghum haiepense (L.) Pers] is the most common and hard to control weed in this crop. The agronomic performance of gram sorghum at different nitrogen (N) and johnsongrass infestation levels in the field has not been adequately investigated. Therefore, research was conducted on a Decatur silty clay loam soil (Rhodic Paleudult) to determine the influence of N rates (0, 40, 80 and 120 kg ha‐1) and johnsongrass infestation levels (0, 2, 4, 6 and 8 plants per 5 m crop row) on the growth and yield of grain sorghum (cv. GK522G) and johnsongrass. Increase in N rates increased seed weight, seed yield and percent protein in grain sorghum as well as dry matter and percent protein of johnsongrass. The increase in johnsongrass infestation (from 0 to 8 plants per 5 m crop row) significantly decreased the performance of grain sorghum and johnsongrass at all the N rates. The results suggest that 40 kg N ha‐1 with up to 2 johnsongrass plants per 5 m crop row or 80 kg N ha‐1 with up to 4 johnsongrass plants per 5 m crop row produced grain sorghum yields equivalent to absence of johnsongrass in the crop.
Stickstoffaufnahme und Stickstoffrückstände von Hauptfrucht‐und Ausfallrapsbeständen
Authors: Aufhammer W. , Kubler E. , Bury M.
Published: April 2008

Nitrogen Uptake and Nitrogen Residuals of Winter Oil‐Seed Rape and Fallout Rape

The objective of the investigation was a study of the relationship between seed dry‐matter production and vegetative dry‐matter production in oil‐seed rape crops and their dependence on the production conditions. In addition to the relationship between the N‐uptake during the vegetation period and the N‐residue after harvest was of major interest. Furthermore the potential for N‐uptake in fallout rape was measured. Over two vegetation periods factorial field experiments with winter oil‐seed rape, cv. Lirabon, different drilling techniques and different nitrogen fertilization levels were tested. Measured traits were: the dry‐matter accumulation including root mass and fall‐off leaf‐material mass, the N‐uptake of both the oil‐seed crops and the fallout rape stands, and, simultaneously, the soil NO3‐N content. Finally the harvest indices and the N‐harvest indices were calculated.

Combined with a N‐uptake of up to 330 kg N/ha, oil‐seed rape crops produced up to 200 dt dry matter/ ha. At seed yield levels of 33dt/ha (d.m.), harvest indices varied from 0.14—0.23 and N‐harvest indices varied from 0.30–0.50. As a result of the residue of vegetative plant material at harvest, leaf losses before harvest and the soil NO3‐N‐contents at harvest up to 275 kg N/ha remained in the field. After the harvest of oil‐seed rape, the soil NO3‐N‐contents were quickly reduced by emerging and growing fallout rape stands. However, following soil‐preparation measures in the autumn, a continuous rise in the soil NO3‐N‐content was observed.
Productivity of Maize (Zea mays L.) in Relation to Morphological and Physiological Characteristics under Varying Amounts of Nitrogen Supply
Authors: Greef J. M.
Published: April 2008

In a field trial located in a northern region of Germany, characterized by a Podzol soil and increasing N fertilization resulted in an enhanced N uptake of the maize (Zea mays L.) variety “Felix” with increasing N fertilization ranging from 0 kg N ha‐1 (N1) to 60 kg N ha‐1 (N2) and to 160 kg N ha‐1 (N3). The growth conditions reached only nearly optimal temperature for biomass allocation in a short period of July and August 1990. The plant productivity was stimulated due to higher N uptake and N utilization to values of nearly 1600 g ha‐1. The N efficiency decreased with increasing N fertilization.

A greenhouse experiment was conducted to study the effects of varied nitrogen nutrition on the development of maize plants under standardized growth conditions, comparable to the sub optimal growth conditions of the field experiment. Physiological and anatomical parameters were measured. Within a range of 0.2—1.0 mg N cm‐2 of leaf nitrogen, the chlorophyll concentration and the CO2 exchange rate showed a linear relationship with the reduced N in the leaf. Above 1.0 mg N cm‐2 no further increases in chlorophyll levels or photosynthesis were observed. Nitrate reductase activity was stimulated throughout the N range supplied. The activities of photosynthetic enzymes (PEP carboxylase, Nadp malic enzyme, RubP carboxylase) was increased from the low (0.19 g N kg‐1 soil) to the middle N level (0.37 g N kg‐1 soil). Under conditions of a high N supply (0.75 g N kg‐1 soil) the activity decreased, except Nadp malic enzyme. This effect was accompanied by alterations of the internal structure of the leaf. Leaf thickness and size of the mesophyll parenchyma were less at the medium nitrate supply. Other anatomical parameters were influenced in proportion to leaf nitrogen status. Stomatal index was not affected by N supply, but lengths and widths of epidermal and stomatal cells as well as the distance between stomata and vascular bundles were increased by high N supply. It is proposed that above an optimal range of leaf nitrogen, maize plants cannot use the potential advantage of the C4 mechanism and the N utilization shows maximum efficiency in the intermediate N level under the sub optimal growth conditions used in the greenhouse experiment.
Effect of Weed Removal on Productivity of Chickpea (Cicer arietinum L.) and Lentil (Lens culinaris Med.) in a Mediterranean Environment
Authors: AL‐Thahabi S. A. , Yasin J. Z. , ABU‐Irmaileh B. E. , Haddad N. I. , Saxena M. C.
Published: April 2008

Three field experiments were conducted on chickpea (Cicer arietinum L.) and four on lentil (Lens culinaris Med.) at different winter‐sown rainfed locations in Jordan from 1988/89 to 1990/91 to study the effect of the duration of weed‐free and weed‐infested conditions on yields and yield components of the crops. Chickpea seed yields were reduced on average by 81 % and straw yields by 63 % when fields remained weed infested until harvest compared with weed‐free conditions throughout the growing season. The corresponding lentil seed and straw yield decreases were 63 % and 55 %. As the duration of weed‐free period increased and the duration of weed‐infested period decreased, yields increased. However, the critical period of weed interference was between 35 and 49 days after emergence in chickpea and between 49 and 56 days after emergence in lentil, when these crops were at an advanced stage of vegetative growth. There were significant negative correlations between the weed dry weight and the seed or straw yields. The reduction in seed yields in both crops because of weed interference occurred mainly through the reduced number of pods /plant, which in turn was partly the result of reduced number of secondary branches. In chickpea, some reduction also occurred through reduced 100‐seed weight.
Adaptation of Aromatic Burley Tobacco Varieties to Northern Italian Environments
Authors: Castelli F. , Carotenuto R. , Contillo R. , Galiotto L. , Miceli F.
Published: April 2008

From 1985 to 1987, eight varieties of domestic and foreign Burley tobacco were studied in some Northern Italy locations (Veneto Region), as an alternative to the air‐cured light and dark tobacco presently grown in that area.

An average 3‐year yield equal to or higher than 3 t ha of cured leaf was obtained for all the tested varieties, which indicates a general adaptation to the environment. Early‐flowering types were more productive than late‐flowering ones; the qualitative leaf traits (alkaloid content, combustibility and specific leaf weight) were mainly related to the growing seasons. The yield stability test and the mean leaf yields highlighted the CAS 83–1A and CAS 83‐lE cultivars as high‐yielding and stable genotypes, and Virginia 528 as a medium to high yielding genotype adapted to less favourable conditions.
Bio‐mass Production in Potato in Relation to Evapotranspiration and Energy Summation Indices in Northern Hills of India
Authors: Nagarajan S. , Sukumaran N. P. , Sastry P. S. N.
Published: April 2008

In field experiments conducted for 2 consecutive years at Shimla (31°06′N, 77°10′E at 2202 m above mean sea level with potato (Solarium tuberosum L.), weekly means of rainfall (P), potential evapotranspiration (PET), pan evaporation (PAN) and photosynthetically active radiation (PAR) were estimated during the crop season. It was evident that from April to end of June, the evaporative demand was more than the precipitation and that the crop suffered from water deficit from emergence to tuber initiation. Four different energy summation indices accumulated over important phenological stages of growth and energy‐use efficiency in terms of biomass production at these stages were estimated for two seasons. Weekly cumulative biomass production showed a significant correlation with accumulated PET, PAN and PAR in the four genotypes tested in year 2.
Evaluation of Rhizobium mdiloti Strains Isolated from Indigenous Populations in Northern Greece
Authors: Embalomatis A. , Papaxosta D. K. , Katinakis P.
Published: April 2008

Eight different Rhizobium meliloti strains (designated as strains 3, 6, 8, 15, 17, 18, 19 and 22) were isolated from fields cultivated with alfalfa. The growth characteristics of the isolated strains under different NaCl concentrations were investigated. Strains 15 and 22 showed marked tolerance to high NaCl concentration.

Symbiosis of one alfalfa variety (Medicago sativa cv. Ipati) inoculated with these strains showed marked differences in nitrogen fixing characteristics (nodule number, dry weight and total nitrogen content). Strains 8, 15 and 22 demonstrated the best performance with respect to all characteristics examined.

The supply of low levels of nitrate to inoculated alfalfa plants affected all the nitrogen fixing characteristics. Nodule number per plant decreased and the ranking of the different strains with respect to nodule number was altered. Dry weight was significantly increased by the supply of the nitrate, even in the case of symbioses with the highly effective strains 8, 15 and 22. Total nitrogen content was increased by the supply of nitrate. This increase was higher in plants inoculated with the less effective strains.
Morphologische und agronomische Merkmale autochthoner annueller Medicago‐Arten in Marokko
Authors: Cremer‐Bach M. , Bach M.
Published: April 2008

Morphological and agronomic characteristics of autochthonous annual Medkago species in Morocco

Autochthonous annual Medicago species were collected on non‐alkaline soils and evaluated as to their potential agricultural use. 411 Medicago ecotypes were found at 108 sites. With increasing rainfall and altitude of collecting sites, a decrease was recorded in the length of sprouts, in sward height, in leaf size, and in dry matter yield. High rainfall regions were found to select late flowering ecotypes. All Medicago ecotypes tested showed broad intraspecific variation in seed yield, leaf size and seed weight. Coumestrol content of leaves at flowering was generally low; on average 115 ppm of dry matter. No relationship was found between collection sites and coumestrol content. In a field trial comparing 112 ecotypes with nine introduced cultivars at two contrasting sites, thirty ecotypes proved to be better adapted to local conditions than the cultivars.
Response of Sweet Potato (Ipomoea batatas L.) to Different Planting Times
Authors: Sangakkara U. R.
Published: April 2008

Agricultural seasons of the tropics are associated with rainfall, which provides the principal limiting resource for crop production. However, as tuber crops are sensitive to temperatures and moisture, the time of planting could have a profound influence on yields. Thus a study was carried out over a period of 12 months to determine the effect of different planting times on establishment, tuber initiation and yields of sweet potato. The trial was planted on similar soils in two agroecological zones as this species is a popular home garden crop in most regions of the tropics and subtropics.

Planting sweet potato with the onset of rains in October produced the highest yields. This is attributed to the receipt of adequate rainfall over the growth cycle, along with the higher diurnal variation in temperatures. Planting in the dry season or later in the wet season, which receives a lower quantity of rainfall with low diurnal variations in temperatures delayed tuber initiation and reduced yields. The study highlights differences in growth patterns of sweet potato when planed at different times. The importance of planting sweet potato in agricultural systems at appropriate times to produce higher yields is presented.
Soybean Yield and Yield Components in Two Planting Patterns
Authors: Ikeda T. , Saito H. , Matsuda R. , Sato S.
Published: April 2008

Soybean [Glycine max (L.) Merr.] plant density for maximum yield in Japan is usually from 16 to 25 plants m−2. The objective of this study was to compare yield and yield components, especially node number between square‐ and zigzag‐ (an equilateral triangle‐planting pattern or plants in the row offset from each other) planting patterns within a range of plant populations (16, 20 and 25 plants m−2).

Field experiments with cultivar Enrei (Maturity Group VII) were conducted in the field at Niigata University on a loamy sand soil in 1991, 1992 and 1993.

Yield increased as density decreased in 1991 and as density increased in 1992 and 1993. This result seemed to be due to adverse weather conditions during seed filling in 1991. Yield tended to be higher in zigzag‐ than in square‐planting patterns except at 20 plants m−2. Seed number m−2 due to increased yield was highly correlated with branch node number. The yield increase was caused by an increase in total node number, especially branch node number m−2 (about 60 % contribution at 16 plants m−2 and about 40 % contribution at 25 plants m−2).
Infiltration of Simulated Rainfall: Dry Aggregate Size Effects
Authors: Unger Paul W. , Jones Ordie R.
Published: April 2008

Water conservation often is limited by soil conditions that cause runoff, even from small rainstorms. This study evaluated the influence of tillage‐induced aggregates on infiltration into Pullman soil (Torrertic Paleustoll). Tillage methods were PLOW (plowing and disking), ROTO (rotary), SWEEP (sweep), or NOTILL (no‐tillage). Aggregate sizes were <0.42, 0.42—0.84, 0.84—2.0, 2.0—6.4, and 6.4—18.3mm. Rainwater was applied until runoff and percolation became constant. Final infiltration (If) rates differed due to tillage, aggregate size, and interaction effects, but maximum difference was only 8.1 mm h−1, suggesting that If rate differences have little significance from a water conservation viewpoint during intense, short‐duration rainstorms that occur in semiarid regions. Cumulative infiltration (Ic) apparently is of greater significance; it was greatest for large aggregates. The PLOW treatment resulted in most large aggregates and presumably would result in greatest Ic. However, under field conditions, Ic was similar for PLOW and SWEEP treatments. For the SWEEP treatment, tillage undercut the surface and retained more residues, thus negating the advantage of larger, but apparently less stable, aggregates with the PLOW treatment with respect to Ic.
Vorfruchtwirkurigen unterschiedlicher Rotationsbrachen auf Winterweizen
Authors: Von Boberfeld W. Opitz , Jasper J.
Published: April 2008

Effects of rotational fallows (‘set‐aside land’) on subsequent winter wheat. The aim of the present study was to investigate the effects of different fallow treatment on subsequent winter wheat. The field trials included rotational fallows planted with Trifolium repens, Festuca rubra and Lolium perenne sown under winter barley compared to complete fallow and natural fallow without seed application and fallows planted with Trifolium pratense, Festuca rubra and Dactylis glomerata sown under winter wheat. After ploughing up the fallow vegetation, winter wheat was planted for 2 succeeding years at two levels of N‐fertilization. Herbicides and fungicides were not applied. The following criteria were investigated: biomass‐production, N‐uptake, yield, weed infestation, nitrate and water content of the soil. In autumn, after ploughing up the fallow vegetation, the nitrate content of the soil (0—150 cm) increased by up to 210 kg NO3‐N/ha after complete fallow, by up to 60 kg NO3‐N/ha after natural fallow and by up to 75 and 130 kg NO3‐N/ha after fallows cropped with Trifolium repens and Trifolium pratense, respectively. Low nitrate levels of 20—27 kg NO3‐N/ha were observed after fallows planted with grass. N‐immobilization caused by ploughing up grass fallows continued until the first harvest of the subsequent winter wheat. In the second year of winter‐wheat, no differences of N‐mineralization dependent on the previous fallow crop occurred, except in the case complete fallow which showed lower N‐mineralization. It can be concluded that fallows cropped with grass lead to a higher nitrogen fertilizer requirement m the succeeding crops. Festuca rubra was able to form dense swards in strong competition with weeds and to decrease the abundance of Alopecurus myosuroides and Apera spíca‐venti in subsequent winter wheat, while natural fallow and fallow planted with Trifolium repens and Lolium perenne caused epidemical increases in grass‐weed density. Preceding crop effects on grain yield of the winter wheat showed a close relation to N‐supply and were compensated by mineral N‐fertilization. After natural fallow and fallow covered with Trifolinm repens, yield reductions due to grass‐weed competition occurred. Undersown Festuca rubra seems to possess a special suitabihty for cultivation in routional fallows. It establishes itself strongly under different cover crops and is able to form dense swards in strong competition with weeds. Grass‐weed density in the succeeding crops will be reduced and nitrate leaching will still be prevented after ploughing up the fallow vegetation. N‐fertilization of the subsequent crops must be carried out under considerations of higher N‐requirements which is probably not entirely due to a stronger N‐immobilization.
Competitive Interactions between First‐year Seedlings of Timothy (Phleum pratense L.) and Meadow Fescue (Festuca pratensis Huds.)
Authors: Jørgensen M. , Nösberger J.
Published: April 2008

Shoot‐ and full‐competition between first‐year seedlings of meadow fescue (Festuca pratensis Huds.) and timothy (Phleum pratense L.) was studied m two separate experiments in a greenhouse. Timothy had a higher competitive ability than meadow fescue and produced more tillers, had a higher shoot weight and a larger leaf area in all strata of the canopy.

Competition for light was important up to the first harvest. The upright growth form of timothy plants during the reproductive phase enabled them to shade the unvernalized and prostrately‐growing meadow fescue. Root competition may have been important afterwards. After the first harvest, tiller formation in timothy plants was high, and significantly enhanced when grown with meadow fescue. Meadow fescue produced few new tillers, and its tiller formation was depressed when competing with timothy.