摘要:

AbstractThe influence of main species (Lolium multiflorum Lam., Lolium X boucheanum Kunth, Lolium perenne L. and Dactylis glomerata L.), sward density, nitrogen and time on yield, energy content, crudeprotein/energy ratio and nitrate contentThe aim of this investigation was to determine the influence of different rates of nitrogen fertilizer and of varied sward density on yield and chemical composition of some non‐perennial (Lolium multiflorum, LoliumXboucheanum)and some perennial species (Lolium perenne, Dactylis glomerata) in a field experiment.Excepted 600 kg N ha−l‐ yr−1the non‐perennial species produced the highest energy yields. At a fertilization level of 400 kg N ha−1yr−1had sward density an influence on energy yield ofLolium multiflorum.It appeared that almost the energy content of theLoliumspecies was higher than inDactylis glomerata.In most cases there were little differences between theLoliumspecies. There was a positive correlation between the NFEcontent and the content of water soluble carbohydrates and the energy content which was depressed by applying increasing rates of fertilizer. Generally at the lowest rate of nitrogen used (200 kg N ha−1yr−1) there were positive effects on crude protein/energy ratios. The crude protein/energy ratio was higher ofDactylis glomeratathan that of theLoliumspecies. The nitrate content increased to critical values when applying 400 kg N ha−1yr−1.Dactylis glomeratahad the highest andLolium perennethe lowest nitrate content. At high rate of fertilizer, plots with high sward density sometimes had higher nitrate contents than open swards.The results of the experiment indicate that there are differences in quality even between species with high performance. Regarding the quality of grass swards, future attention should be focused on the main species

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00819.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractNO3dynamics in the soil, yield formation and N uptake of winter wheat as influenced by dosage and distribution effects of N‐fertilizer applicationIn a 4 year series of field trials carried out with 9 regimes of nitrogen fertilizer application at two trial sites with rather shallow top soil layers but large deviations in soil characteristics, grain yield varied between 50 dt/ ha and 120 dt/ha with nitrogen doses from 0–170 kg N/ha. Soil nitrogen supply for wheat grain formation on unfertilized plots reached 80 kg N/ha/year within the narrow range of 75–95 kg N/ha in different years at both sites which amounts to 1.5 % and 0.5 % of the highly different N‐content of the trial sites.The most successful nitrogen application regimes are characterized by modest fertilizer doses in early spring and the delay of supplemental fertilizer doses until growth stage EC 32. They resulted into modest NO) soil content from EC 29 to EC 32 and/or a noticable decrease of soil NO3content during growth stage EC 30–32, which seems to be responsible for the development of only modest stand densities and reduced straw yield, while the delayed supplementation with nitrogen fertilizer overcompensated these effects mainly by increased grain numbers/ear and a remarkable improvement of harvest index.The contribution of soil borne nitrogen to kernel yield formation started to decrease with even low dosages of supplemental nitrogen fertilization with the exception of the highest yielding season 1987/88. Top levels of grain yield have been regularly obtained with supplemental nitrogen fertilizer dosages about 40 kg N/ha below grain yield nitrogen extraction if they were added within favorable applicatio

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00820.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of thermal energy intensity (TEI) on the rate of nitrogen (N) accumulation by maize from a Hamerly clay loam soil (Aerie Calciaquoll) was examined with and without supplemental irrigation. Soil‐ and air‐TEI expressed as cumulative growing degree days (GDD) was determined from hourly temperature measurements taken within each plot at soil depths of 0.05‐, 0.15‐, and 0.3‐m and at a height of 1.2‐m above ground surface. A daily mean TEI (GDD per day) was calculated for each growth period. Estimates of time coefficient(s), k, in uni‐ and diphasic tanh[k(time)] functions, plotted against mean TEI for the periods; 1) planting to emergence, 2) emergence to eighth leaf, 3) eighth leaf to time(s) of maximum N accumulation rate, (t0), 4) planting to t0, 5) emergence to t0, 6) first diphasic maximum accumulation rate (t01) to 50 % silking, and 7) silking to second diphasic maximum accumulation rate t02showed several linear relationships. Uniphasic time coefficients were modelled as functions of air‐TEI. The first diphasic time coefficient, k1was modelled as a function of pre‐ and post‐emergent soil‐TEI. Attempts to model k2, the second time coefficient of the diphasic model were unsuccessful; however, this time coefficient was linearly related to TEI for the growth period ‘t01, to 50 % silking’ and cu

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00821.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA greenhouse experiment was conducted to study N distribution and dry matter accumulation in oilseed rape (Brassica napusL. cv.Callypso) in relation to N supply. Three levels of N supply (30, 100 or 170 ppm N) were tested as treatments. Stem and leaf dry weights increased at higher N fertility up to 170 ppm N but root dry weight did not respond to N. Dry matter yield during the vegetative phase was seriously depressed by N deficiency. Most of the plant dry matter was accumulated in the lower segments of the stem and roots. Dry weights of stem and axillary branches increased significantly as N supply increased up to 100 ppm N. Although hull dry weight increased with N supply up to 100 ppm N, seed dry weight did not respond to N. High root N concentration was maintained at 100 or 170 ppm N; but declined as plants advanced in age. N content of leaf and stem also declined with time. Leaf growth was particularly responsive to N fertility and N was mobilised from the older to the younger leaves over time. Nitrogen content of hulls and seeds increased significantly with N supply but N was translocated from the vegetative into the generative organs or from older into younger tissues during pod development. There is need for proper N fertility management in order to achieve successful rape production.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00822.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractMaize dominated cassava irrespective of cassava or maize growth habit and the optimum maize population giving the highest production based on relative yield total or land equivalent ratio varied with maize variety in a tropical Alfisol at Ibadan, transition humid/subhumid zone in West Africa. The sparsely vegetative, early maize supported higher intercrop maize population (up to 80,000 ha−1) than the late maturing, highly vegetative TZSRW. Because there is a compensatory relationship in the yields of the two crop components, the choice of an appropriate crop type and maize population in cassava + maize intercrop system will depend on the relative economic importance of each crop componen

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00823.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe changes in photosynthetic rate and translocation of photosynthates in winter wheat (Triticum AestivumL.) grown in lysimeters were studied, in response to periodic soil water deficit during late tillering and flowering stages. Soil water deficits were imposed to previously nonstressed plants during late tillering and flowering states. Timing of irrigation was scheduled according to the ratio between irrigation water applied and cumulative pan evaporation (IW/CPE) of 0.75 (low deficit), and 0.5 (moderate deficit), as well as by suspending irrigations after crown root initiation stage (severe deficit). To determine the rate of photosynthesis, a short radioactive pulse of14CO2with 300 ppm concentration was given to second leaf from the top at tillering, and to the flag leaf at flowering stages for 20 second exposure time. The translocation of photosynthates was estimated by scanning14C activity in different plant parts. In late tillering the midday Photosynthetic rate (PR) was significantly 3 mg CO2dm−2h−1lower under low water deficit (WD1) than under zero water deficit (WD0). Under higher stress conditions, soil water acted as a limiting factor to keep the rate from rising above 13.2 during stress at late tillering (WD2), 14.5 flowering (WD4), and 10.0 mg CO2dm−2h−1for stress at both the growth stages (WD5), respectively. The difference in daily accumulated photosynthesis (8 h), between stressed and nonstressed were 15, 40, 42, and 77 mg CO2dm−2h−1respectively at WD1WD2, WD4, and WD5. The retention of14C in flag leaf decreased considerably after 24 hours of exposure time when the labelled assimilates were translocated in bulk to the ear head. Under stressed condition a general trend was observed for upward translocation of assimilates towards the ear, even from the stem and root. The percent14C activity observed in ear after 24 hours was greatest in severely stressed plants. The photosynthetic rate is reasonable predicted by midday LDR and surfa

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00824.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA distribution to the availability of the nitrogen in sewage sludges stabilized with different processesIn two pot experiments the availability of the nitrogen in sewage sludges stabilized with different processes was investigated. Further it was examined whether the Quantofix‐N‐Volumeter (method for rapid determination of ammonia in slurries) is able to determine the plant available nitrogen in sewage sludge.The following results were obtained:In the experiment where same amounts of total N were applied as sewage sludge a highly significant correlation existed between the amount of NH4‐N applied and the N uptake of the plants.When equal amounts of NH4‐N were applied the N uptake was lowest with the sewage sludges with a high relative part of NH4‐N of the total N (thermophile‐aerob; mesophile‐anaerob). However the reason for this result was not only the lower application rate of total N with these sewage sludges but also the lower efficiency of the organically bound nitrogen.A very highly significant correlation existed between the application rate of organically bound nitrogen and the N uptake.The values of nitrogen in sewage sludges measured by the rapid method gave information about the plant available nitrogen in the year of application.A close quantitative agreement existed between the available nitrogen determined with the rapid method and the values calculated with the formula of Furrerand B

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00825.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractTwenty‐two genotypes of grain sorghum were grown under drought conditions by omitting one irrigation during stages of before flowering period, kernel filling period, and physiological maturity period at Assiut Univ. Farm in 1987 and 1988 seasons. The results obtained revealed that considerable variation existed among genotypes for all the studied traits. The most effective moisture stress treatment in reducing grain yield, panicle weight and plant height was during flowering stage. While 1000‐kernel weight was much affected by moisture stress during grain filling period. The genotype x year interaction (σ2gy) was large compared to genotype x irrigation treatment (σ2gl) indicated that genotypes responded differently when they were grown from year to year. The genotypic variance (σ2g) for all traits were large reflecting the importance of genetic variability. Both phenotypic and genotypic correlations among traits showed that plant height and 1000‐kernel weight were highly correlated with grain yield, while leaf area index was low associated with plan

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1990.tb00826.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY