摘要:

AbstractInfluence of ascending nitrogen supply on the development of Rhizobium symbiotic bacteria on peas (Pisum sativumL. ssp.sativum) in nutritive culture solutionThe effect of ascending N‐supply with 4 different levels from 0.1 to 1.56 mg atom/L culture solution on juncture, quantity and development of Rhizobium bacteria on peas varietyStehgoltwas thoroughly investigated. Contemporaneously, all the inoculated plants set on several noduls. The number of nodules formed per plant was negatively and hasty influenced by the ascending N‐supply. Higher N‐provision lessen the number of Rhizobium nodules per plant, however, these few achieved their active N2‐Fixation phase (Leghämoglobin formation stage) earlier than those formed under insufficient

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00719.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThis study was undertaken to determine the relationship between sixth leaf area and total leaf area of sorghum (Sorghum bicolorMoench) to obtain the total leaf area estimate without having to make the time consuming area measurement directly. Ten sorghum varieties were raised at Tamil Nadu Agricultural University campus Coimbatore from which the leaf samples were taken. The allometric relationship derived by logarithmic transformation between total leaf area (TLA) and sixth leaf area measured by leaf area meter (SLALW) and TLA and sixth leaf area measured by maximum length and width (SLALW) were not different significantly. The allometric relationship for all the ten varieties of pooled data wereTLA = 27.416 (SLAM)0.794and TLA = 14.355 (SLALW)0.857)Where TLA, SLAMand SLALWare measured in cm2. The standard error of estimate equalled to 0.00299 and 0.0035 for the regression of TLA‐SLAMand TLA‐SLALWrespectively. The correlation co‐efficients for TLA‐SLAMand TLA‐SLALWwere 0.94 and 0.93 respectively. Among the relationships tried for third, fourth, fifth, sixth and seventh leaf area by meter and length X width verses total leaf area, the SLA verses TLA found to be more

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractMany factors affect nodulation of legumes of which, nitrogen fertilizer and method of inoculation play a vital role. Thus, a study evaluated the effects of the above factors on nodulation and yields of two common tropical food legumes, namely Mungbean and Bushbeans which are considered extensive and poor nodulatingo species respectively.Inoculation increased nodulation of bushbeans and to a lesser extent in mungbeans. This effect was more evident with time. Nodulation was reduced in the presence of nitrogen fertilizer, and the effect was more pronounced in the extensively nodulating species, mungbean. Nitrogen and nodulation increased yields of both species. The results indicate the inability of bushbeans and to a lesser extent mungbean, to meet all nitrogen requirements by nodulation and nitrogen fixation alone. This suggests the need for some fertilizer nitrogen for tropical legumes in addition to inoculation to obtain optimal yields.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00721.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 slurry in order to study the long‐term effect of slurry and the effect of application time (no slurry, slurry autumn, slurry spring) on the dynamics of nitrogen in the soil.The results can be summarized as follows:On the farm with long‐term application of slurry, (“livestock farm”), nitrate‐content in the soil was markedly higher than on the farm without slurry application (“arable farm”). This is due to a more intensive N‐mineralization during autumn and spring. On the livestock farm a remarkably high mineralization of nitrogen was observed at soil temperatures near 0°C, while on the “arable farm” N‐mineralization started only at temperatures above +4°C.The high N‐mineralization during autumn on the “livestock farm” implies the risk of N leaching into deeper soil layers during winter.Slurry application caused a large increase of mineralized nitrogen in soil. No site‐differences in decomposition of actual slurry applications have been observed.High N infiltration‐rates may occur when slurry is applied in autumn, depending on the amount of autumn and winter rainfall. Thes risk of nitrogen leaching also persists, when slurry is applied in spring and crops with late N‐uptake are cultivated (e.g. sugar beet).The intensive leaching of nitrogen after application of slurry is caused by the fast nitrification of slurry‐NH4, wh

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPot and field experiments were conducted with two varieties of maize to study the effects of nitrogen applied in different doses. The total amount of N applied was same in all variants of one experiment. The development of maize plants varied due to variety and N‐doses. In pot experiment no N application before sowing or in the begin of the ear differentiation reduced total number of spikelets, spikelet rows/ear, length of ear, kernel yield as well as plant height. In field experiments an amount of 30 kg N/ha in the begin of ear formation was sufficient for maximum increase in almost all yield characteristics. Higher doses than that were not effective to promote these parameters furthe

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractImpact of Wheat Breeding in an Agricultural Low External Input SystemLow external input systems, e.g. ecological agriculture, are able to solve problems concerning environmental pollution, diminishing ressources, and overproduction. Since growing conditions of winter wheat are very different in ecological agriculture as compared to conventional systems, the impact of genetic improvement of winter wheat in low external input systems is not well known. Investigations were carried out in two years at two ecologically managed farms using 24 genotypes of winter wheat of different periods of release (about 1900 to 1983). The results can be summarized as follows:1. The tendency towards higher yields among modern varieties as compared to older cultivars in ecological agriculture was highly significant.2. The rate of yield improvement was smaller under low external input as compared to conventional conditions results. Yield improvement was greatest in recent decades.3. In ecological agriculture higher yields among modern varieties resulted from an increased harvest index along with an unchanged biomass production, improved resistance properties, and higher ear weight. Reduced plant height probably has negative effects.4. Baking quality was improved clearly by wheat breeding.5. Further genetic improvement of winter wheat yields in low external input systems may result from increased biomass production along with a constant or enhanced harvest index, improved resistance properties, increased plant height, and pronounciation of ear weight.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00724.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractStructure, microbial metabolism and potentially mineralizable nitrogen pools in organically and conventionally farmed clay soilsSoil physical, soil chemical and biological studies were carried out on two differently cultivated clay soils. One soil, under organic farming system (TNL), was not ploughed for the last 14 years, the 0–10 cm layer was tilled by a rotowator system. The other soil was tilled conventionally and was ploughed down to 22 cm (TKL). For comparison the topsoil of a pasture was investigated.The saturated hydraulic conductivity (depicted as frequency distribution from ktvalues) was very high in the TNL soil and in the pasture soil. The TKL soil showed a lower conductivity and pore continuity than the other soils, especially in the layer of 0–10 cm (Aprhonzon). Aggregate stability (measured as total settlement) was highest in the pasture soil, followed by the 10–20 cm layer of TKL soil. The small fragments of TNL soil resulted in a decline of the aggregate stability.Dehydrogenase activity was similar in the TNL soil and the pasture, and lower in the TKL soil. Potentially mineralizable nitrogen showed the same trend as dehydrogenase activity. Soil respiration was higher in the TKL soil than in the TNL soil. This was attributed to higher amounts of microbial available carbon probably because of the presence of undecomposed crop residues in the TKL

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00725.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractDefoliation hastens senescence of the capsule wall, increased seed weight/capsule and harvest index, promotes seed filling and decreased the post‐flowering contribution and yield/plant. Defruiting delayed senescence of the subtending leaf. Treatment of kinetin on the capsule wall increased its chlorophyll, sugar and dry weight and also increased yield by increasing harvest index, seed weight/capsule compared to seed treatment as well as control, although post‐flowering contribution reduced significantly. When treated on the capsule wall ABA defers senescence of both leaf and capsule wall and also increased the yield parameters but seed treatment although defers senescence of both the source organs, decreased the yield parameters. Treatment of urea defers senescence of the source organs and also increased yield and capsule number though harvest index was reduced.It is concluded that contribution from the capsule wall and deferment of senescence of this organ at the post capsule development period determines yield and in normal condition contribution of source is limited by the sink s

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00726.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractOver the course of two planting seasons field trials were conducted at the CIAT farm in Palmira (Colombia). The experiments included nine tropical bean lines grown in pure stands and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number.In the case of several pure lines, inferior seed quality led to low germination and uneven population densities, especially in the first planting season. Analogously, missing plants also occurred with the corresponding mixtures. A significant and positive relationship between mixing induced yield gains and patchiness in mixtures was found, indicating that intergenotypic compensation was a major determinant for mixture effects on yield. In common bean as a tropical subsistence crop seed quality is known to be erratic. It is concluded that compensation effects in mixtures of common bean may be expected to be of practical importance regarding the improvement of yield stability over seasons.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00727.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe pattern of grain growth in two rice cultivars was assessed in terms of total dry weight of grain from anthesis upto maturity. Rice grain development followed a sigmoidal trend. Richards' function was found to more closely fie the data on grain growth and thus could serve as a suitable mathematical model for rice grain growth analysis.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1989.tb00728.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY