摘要:

AbstractIn 31 field experiments with sugar beet, carried out in 1982–84 in Scania, southern Sweden, fertilizer nitrogen recovery in tops and beets, calculated with the difference method, amounted to 73%. To elucidate the role of the fine lateral roots in the fate of the nitrogen not accounted for, the lateral roots within depths of 0–25 and 25–60 cm were sampled at harvest in late September, 1984 in five sugar beet experiments. Irrespective of differences in nitrogen fertilization and plant‐available soil nitrogen, a mean of ca. 3 kg/ha−1of nitrogen was found in the fine lateral roots. This corresponded to only ca. 2% of the nitrogen in the whole crop at harvest, whereas the beets and tops contained 43 and 55%, respectively. Using the difference method, calculations with, as well as without, fine roots therefore yielded the same recover (75%) of fertilizer nitrogen in the beet crop. The increase of residual mineral nitrogen in the soil at harvest caused by the fertilization corresponded to 2% of the fertilizer nitrogen applied. This means a total recove

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00605.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractSoybean (Glycine max[L.] Merr.) grain yields may be reduced when the plants lodge. The magnitude of yield reduction is dependent on the growth stage at which lodging occurs. The stage of plant development most vulnerable to yield reduction from lodging has not been conclusively determined. The objective of this two‐year study was to determine soybean yield reduction caused by simulated lodging at three stages of reproductive development: the onset of flowering (R1), beginning pod (R3) and beginning seed (R5). At each developmental stage the plants were lodged at either 45° or 90°. A natural lodging control and an artificially maintained erect treatment were included.The 1976 results indicated no yield differences due to any of the lodging treatments. In 1977, yields were significantly reduced for the R3 lodging treatments. Soybeans lodged 90° at the R1, R3, and R5 growth stages yielded 2.63, 1.88 and 2.26 Mg ha−1, respectively. The natural lodging and erect treatments yielded 2.73 and 2.43 Mg ha−1, respectively.Lodging treatments applied at the R1 stage produced plants with a two‐year average of 30% of their seeds on the main stems, compared to 62% of the seeds on the main stems for the R5 stage treatments. The percentage of seeds on the main stem was 69% on the erect plants, as compared with 45% on the 90° lodged plants. In 1977, lodging treatments also reduced pods per plant, seeds per plant, 100 seed weight and seed weigh

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00606.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn the year 1979, 1981 and 1982 two‐factorial experiments with the factors genotypes and crop densities were conducted, connected with the following agrometeorological analyses:a) outside the canopies: determination of air temperature, air humidity, wind velocity, precipitation, global radiation and photosynthetically active radiation (PAR)b) in the interior of the canopies: measurements of air temperature at cobheight, of precipitation components, of the penetration of PAR and of the leaf area index.The following results were obtained:a) Influence of high crop densities1. In high crop densities the greatest part of radiation was absorbed, so that at 30 plants/m257% and at 70 plants/m2only 28% of the PAR reached cob height.2. As a consequence of temperature and decrease of radiation the contents in the leaves of biological energy, of water soluble K.H. and rough protein were reduced.b) Influence of the leaf posture3. For genotypes with erected leaf posture the leaf temperatures increased by 0.3°C, on the ground even by 1.2°C above the values of the stand with horizontal leaf posture.4. Higher air temperatures were measured in the stands with erected leaf posture than in those with a horizontal one.5. In the cool year 1981 on days with temperatures above 27°C outside the stands, those temperatures were exceeded during 7 hours in canopies with erected leaf posture at a higher plant density (30 plants/m2) and only during 2 hours in canopies with a horizontal leaf pos

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00607.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA description is given of a PVC‐container installation which allows the determination of plant yield as well as the measurement of water flow. The single containers with 600–700 kg soil are transportable by means of a fork‐lift truck or similar vehicle. Information is given on the insulation and the heating unit (overwintering) of the container as well as on the elimination of border effects, fluctuations in soil temperature etc. An example of practical use, a trial with 48 units with the aim of evaluating the BNF (closed system) of faba beans in a rotation, is described. Detailed instructions (English, French, German) for constructing the container unit are available from the au

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00608.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe present study aimed at studying the effect of boron on pollen characteristics, translocation of water soluble sugars and its importance as a specific nutrient for seed production in lucerne. Aquous solutions of borax (0, 2500, 5000, 7500, 10 000 and 20 000 ppm) were sprayed at flowering stage. After 20 days, the fresh flowers were collected from the plants of all the treatments separately. The pollen was dusted on glass slides containing Muntzing's mixture for staining. After 6 hours, the data on pollen size, stainability and germination were recorded in 10 randomly selected microscopic fields. The estimation of water soluble sugars and boron content in flowers was done by standard methods. Data on grains per pod, grains per inflorescence and 1000 seed weight were recorded at seed maturity. With increasing rates of applied B, pollen germination, water soluble sugars, boron content and number of seeds per pod and per inflorescence increased but pollen fertility decreased. The pollen size and 1000 seed weight was not affected by boron concentrations. The results indicate that boron plays a definite role in increasing the seed yields through stimulating the physiological processes during reproductive phase.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00609.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis investigation measured plant dry matter accumulation in guar [Cyamopsis tetragonoloba(L.) Taub.] grown under water‐optimal and water‐stressed field conditions. Twelve guar genotypes were planted in irrigated and dryland tests at Chillicothe, TX on a Miles fine sandy loam (fine‐loamy mixed, thermic Udic Paleustalf). Dry weight harvests were made at 60, 90, 120, and 150 days after planting (DAP).Significant variation was found among guar genotypes within maturity groups for plant dry matter accumulation. Percentage shoot dry weight in reproductive parts (pods) ranged from 41 to 79 % among the 12 genotypes at 150 DAP. Percentage stem weight, expressed as a percentage of shoot weight, averaged 36% at 60 DAP and 40% at 150 DAP. Percentage leaves decreased from 60% at 60 DAP to 0 at 150 DAP.Genotypic differences were found in irrigation water use efficiency (IWUE). IWUE was highest forLewis(28.3) and lowest forHall(5.4). Medium maturing genotypes, with the exception ofLewis, had similar IWUE's ranging from 16.3 to 19.2. Early and late maturing genotypes generally had relatively low IWUE's. Genotypes differed significantly in harvest index (ratio of seed to shoot weight). Harvest indices ranged from 0.20 to 0.48. Harvest indices of the same magnitude were found in the water‐optimal and the water‐stres

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00610.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe present investigation was undertaken on four W. German (AD201, Belinda, Korina and Elvira) and five French (Cresor, Brutor, BRO, BRIO and Orpal) spring rapeseed varieties, for evaluation and to study their performance and productivity under Fayoum (Egypt) conditions during two successive winter seasons (1982/1983 and 1983/1984). In order to make clear identification for different plant characters, some genetical parameters were estimated.In the first season, the nine varieties were arranged into a randomized complete block field experiment with four replications. In the second one, the experiment (with the same design and replication) included only six cultivars, after elimination of three winter‐type (Belinda, Korina and Elvira) that failed to reach flowering because of unique cold temperature requirements. Therefore, the present study was restricted with the remainder six varieties.The varieties exhibited considerable differences in all the characters studied. AD201 was earlier, higher seed‐ and oil‐yielding variety than other tested ones. Its superiority could be attributed to increased number of pods/plant, seeds/pod and seed yield/plant. The second yielding variety was BR1O followed by Cresor, BRO and Brutor. While Orpal was inferior in all characters except for seed index. Data showed that fruiting zone length reached nearly half the mature height for each genotype.Remarkable amount of genotypic variation and high heritability estimates were recorded for all studied characters. Quantitative analysis indicated that number of seeds/pod, early flowering, seed weight/plant, possessed high heritability values combined with high genetic gains and wide genetic variations. By these characters, discernible improvement could be easily achieved through phenotypic selection in relatively very short

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00611.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe Tarahumara Indians of the north‐west Mexican Highland practice a method of using several weeds for food which are called “quelites”. These weeds play an important role in the Tarahumara diet and seem to be connected with maize‐cultivation in a special way.In bio‐assays with two quelites species,Bidens pilosasens. lat. (Cobblers' pegs) andLepidium virginicum(Pepper grass) and different cultivars of maize (Zea maysL.) it could be demonstrated that water extracts of leaves ofB. pilosaandL. virginicumcause a significant stimulation of seedling growth of maize. Different cultivars of maize showed no differences in being stimulated by extracts ofB. pilosa.This indicates an allelopathic potential of the two tested quelites species.Extracts of leaves of older plants ofB. pilosa(shortly before flowering) do not show this effect. Different water extracts of maize snowed an indifferent influence on germination and seedling growth ofB. pilosaandL. virginicum.Considering these results the practice of the Tarahumara Indians — leaving the quelites a certain amount of time among their maize and harvesting them after that — appears to be a stimulatory method for growing maize. The maize‐quelites double‐crop system seems to be highly tuned and may be understood as a result of a process of cultural learning among the T

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00612.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractComparative fixation of NH4and K by wetland rice soils in relation to clay mineral composition and treatment sequence is of agronomic interest, but information on the subject is scanty. An attempt has been made to clarify this relationship by employing the normally recommended doses of fertilizers, 3 application sequences, and 5 soil clays of divergent mineralogies. The results show that montmorillonitic clay is the greatest fixer of NH4, but least of K. X‐ray amorphous clay also prefers NH4over K. Vermiculitic and beidellitic clays strongly fix both NH4and K. Soil clay consisting of hydrous mica, chlorite, and halloysite fixes low proportions of applied NH4and K. The sequence in which NH4and K are applied does not appear to affect the relative amounts that are fixe

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00613.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book Reviewed in this article:Hock, B. und E. Elstner. Pflanzentoxikologie.Der Einfluß von Schadstoffen und Schadwirkungen auf Pflanzen.Welte, E. und F. Timmermann: Diingung und Umwelt. Verlag W. Kohlhammer GmbH Stuttgart und Mainz.Jones, C. A.: C4 Grasses and Cereals.Hoffmann, G. M., F, Nienhaus, F. Schonbeck, H. C. Weltzien und H, Wilbert: Lehrbuch der Phytomedizin. 2., neubearb. Aufl

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00614.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY