摘要:

AbstractMeasurements of infiltrability were carried out during the soybean vegetation period in three different tillage systems on an Oxisol, with the aim of estimating relative erosion susceptibility. The tillage systems studied were conventional tillage (disc plow), minimum tillage (chisel plow) and no‐tillage. Infiltration was determined as the difference between rainfall applied with a portable rainfall simulator and runoff collected from mini‐plots.During all growth stages of the soybeans, infiltrability under no‐tillage was higher than under conventional tillage. Minimum tillage took an intermediate position. Lowest overall infiltrability and consequently, highest relative erosion susceptibility was observed in the early growth stage after planting, in a wet year, when the degree of soil cover was also lowest. Infiltrability was mainly affected by degree of surface seal development as a result of natural rainfall energy the soil surface had received prior to measurements, as well as degree of soil cover. Highly significant correlations were found between the calculated sum of erosivity indices one month before measurement and the total infiltration. Differences in bulk density and macroporosity had hardly any effect on infiltrability.The better performance of no‐tillage in controlling erosion observed in Brazil can thus be explained by the higher degree of soil cover in comparison to the other tillage systems

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractStudies were carried out at the Indian Institute of Horticultural Research, Bangalore during winter seasons of 1982—83 and 1983—84 to analyse the growth rhythm of onion in relation to irrigation and N fertilization. It was observed that irrigation at 0.45 to 0.65 bar soil water potential recorded higher dry matter accumulation and distribution, leaf area index (LAI), leaf area duration (LAD), leaf area ratio (LAR) and crop growth rate (CGR) during most of the stages, while net assimilation rate (NAR) and relative growth rate (RGR) were not markedly affected. Highest harvest index was noticed with irrigation at 0.65 bar.Nitrogen fertilization significantly increased dry matter accumulation and distribution into different parts, LAI, LAD, LAR, CGR and harvest index. Although NAR and RGR showed an increasing trend with N fertilization, the effect was not significant during most of the stages. There was no significant interaction between soil water potential and N fertilization on any of the growth paramet

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of natural air temperature on the vegetative growth and alkaloidal yield ofH. muticusL. was studied. The highest number of branches, diameter, fresh and dry weights of stem and roots occurred in September sowing at full‐flowering and fruiting stages. Relatively higher temperature in Sept. sowing favoured leaf growth (number, area and dry weight). Hyoscyamine yield in different organs of the plants sown in Sept., excessively exceeded all other sowings during flower budding and full‐flowering stages. Hyoscine yield was quantitatively very small as compared with that of hyoscyamine and even could not be detected in the leaves of winter sowings during full‐flowering

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractArtificial manipulation of sink and source was carried out in several bread wheat varieties in order to study the variations in the pattern of storage products accumulation in the grain.In a first experiment, partial ablation of the laminae did not cause any significant variation in the yield components, while total elimination of the laminae resulted in a decreased fertility of the spikelets and in a lower kernel weight. The protein content of grain turned out to be a function of the amount of vegetative organs left in the different treatments, and ranged from 11.1 % in leafless plants to 16.5% in the control.The halving of the spikes led to a 14% increase in the size of the kernels, while the protein content per spike showed a 20 % drop in comparison to the control.Reduction of sink affected nitrogen accumulation to a lesser extent than carbohydrates storage in the grain.Reduction of sink induced remarkable increases in the protein fractions: gliadins +59%, glutelins +44%, insoluble residue +30%, non‐proteic nitrogen +28%, albumins and globulins + 16%. The increase of GPC or of specific solubility classes did not influence significantly the quality of the flour evaluated by the Zeleny and Pelshenke indices.The presented data suggest some caution in adopting kernel size and GPC as main selection criteria in early generations. It seems more convenient to select for a prolonged grain filling period and for a higher biomass without increasing plant heigh

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractInbred lines and crosses from cool temperate regions (C) and from warm regions (W) were grown at 14, 22, 30 and 38°C up to the same physiological age, the full expansion of the third leaf. The laminae of the second leaf were studied for anatomical traits. For all traits the genotypic variability was high over the whole temperature range, but the rank order was influenced by temperature. Leaf thickness and cross sectional area of epidermal cells were smallest at 22°C. Stomatal frequency increased in inbred lines from 14 to 38°C and in crosses from 30 to 38°C. In crosses stomatal length was low at 22°C and high at 38°C while inbred lines either did not react to temperature at all (C) or had low to very low values over the whole temperature range (W). Cross sectional area of chlorenchyma cells (mesophyll, bundle sheath) was high at 14°C. For mesophyll cells of inbred lines and generally for bundle sheath cells a second maximum occurred at 30°C. Cross sectional area of both chloroplast types was high at 14°C and low at 22 or 30°C. Positive heterosis was seldom observed but negative heterosis occurred for chlorenchyma cell size at 14°C. This might indicate an improved fitness for photosynthesis at suboptimal temperature because of small cells, especially as W‐genotypes generally had large cells at this temperature. A negative heterosis for the stomatal frequency over the whole temperature range might stand for a good fitness of hybrids for photosynthesis, too.The investigations have shown that the expression of some important anatomical traits is dependent on temperature as well as on origin and genetic structure of mai

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of plant population on yield and quality of sugar beet at different harvesting dateOptimum plant population of sugar beet in respect of corrected sugar yield in Central Europe ranges from 70 000 to 90 000 plants/ha. It is known that extending the length of growing period by later harvesting causes an increase in yield and quality of sugar beet depending on location and weather. There is a lack of information, however, about the effect of plant population on yield and quality increase with postponed harvesting date.The objective of this study was to investigate the influence of plant density and harvesting date on yield and quality of sugar beet.Four trials were carried out at Göttingen (Lower Saxony) from 1982 to 1985 which included each year four plant populations and three harvesting dates (end of September to middle of November).Depending on seed lot, plant spacing and field emergence, plant populations varied between 87 000 and 27 000 plants/ha. Averaged over the years, the plant populations for the different treatments reached 71 000, 51 000, 40 000 and 31 000 plants/ha.Later harvesting date and increasing plant population resulted in higher yield of beet and/or higher sugar content of beet. The increase in corrected sugar yield with extending the length of growing period was highest in plant populations with high density.From the results it can be concluded that by having the choice, a beet crop with the highest plant population should be harvested at the end, a crop with a lower plant population at the beginning of the harvesting period, unless there have to be observed some other aspects (location, crop sequence, field condition)

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractLucerne (Medicago sativaL.) is a valuable forage legume but it is short lived in many regions and periodic reseeding is necessary to maintain adequate lucerne in swards. Sod‐seeding is a fast, one pass method of renovation but variable seedling establishment of sod‐seeded lucerne has been experienced in the Atlantic Region of Canada. Experiments were conducted in two consecutive years to determine seeding date effects on establishment and growth of sod‐seeded lucerne in timothy (Phleum pratenseL.) dominant swards at two sites. In the first experiment lucerne was sod‐seeded on four dates in swards, band sprayed with paraquat at 0.5 kg/ha−1, and was compared with sod‐seeded red clover (Trifolium pratenseL.). In the second experiment the effects of four sod‐seeding dates of lucerne and broadcast or band spraying of paraquat in swards were determined. Sod‐seeding lucerne between late April and mid‐June resulted in the best establishment and yields. Yields of sod‐seeded lucerne were usually greater with broadcast than with band applied paraquat. Red clover established more readily and made a greater contribution to total

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractDue to recent research results breeding of perennial rye to‐day seems possible and in so far desirable as changed premises in agricultural production ask for the invention of new farming systems. Accordingly, the farmer would have to earn his livelihood more by decrease of expenses in a constant production level than by further increase of production quantity. Then, agricultural crops with newly designed characters or even absolutely new crop species particularly with low demands for cultivation, water supply, fertilizer or other agrochemicals (low‐input varieties) could be very helpful. For that a project of breeding “perennial rye” (Secale cereale × Secale montanum), for different farming systems respectively, is presented which has already been performed in some details and which could surely be realized in total if only a small part of the means were invested in this project as for example were spent into the development of Triticale as a new crop plant. Because of its high tolerance to poor sandy soils and water stress a perennial green forage rye may also be expected to be well suited in a spring rye variant for the improvement of dry pastures in the subtropical countries. A corresponding research project has been supported since 1985 by GTZ (Deutsche Gesellschaft für Technische Zusammenarb

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00077.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1986.tb00078.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY