摘要:

AbstractVariety‐specific reaction ofLolium perenneL. on selective systemic herbicidesThe investigation intended to show the specific reaction of different varieties ofLolium perenneon selective systemic herbicides. These results can be regarded as the base for advanced explorations to the described topic. The results may be summarized as follows:Independent of the stage of growth, the date of application, the dosage and the droplet size there were effects on the forage yield in correlation to the variety and the active ingredient. Measurable yield reductions were presented after CMPP application on the varieties of the late and after the treatment with Asulam on the varieties of the early maturity group. Compared to the maturity group the varietal attribute growthhabit demonstrated no significant effects. The active ingredients MCPB and MCPA presented not any measurable influence on the forage yield of the different varieties. In the main harvest year the yield depressions were manifested clearer than in the seeding year. In the same way the described secondary actions were larger after the treatment in an advanced stage.Extended investigations should inquire to the causes and secondary effects on the forage quality. Beyond this for variety testings of species with a large distribution and volume it seems remunerative to include questions of herbicides toleranc

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00670.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe uptake kinetics of nitrate and ammonium ions was compared for the annual range species: subclover (Trifolium subterraneumL.), soft chess (Bromus mollisL.), and broadleaved filaree (Erodium botrys[Cav.] Bertol.) to study competitive interactions in nitrogen deficient soils. Fifteen‐day‐old seedlings were allowed to deplete solutions of nitrate or ammonium in the range of 5 to 500 μM concentrations for a 10‐hour period during which net uptake (depletion) was monitored by a sensitive conductance technique. Subclover uptake rates were markedly less than those for soft chess and filaree for both nitrate and ammonium at both low and high concentrations. The evidence supports the hypothesis that subclover is a poor competitor for soil N in part because of this physiological diff

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00671.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTwo field trials with paddy crop were raised to study the root distribution characteristics under mechanical impedance. Plots varying in bulk density were created by passing 400 kg stone roller (1 meter width) 8 times and 16 times. After harvest of the first crop32P was injected to the paddy stubbles and the percentage of total radioactivity at different layers upto 30 cm was calculated to study the root distribution characteristics. The results revealed that 47.2 per cent of the roots are distributed in the first 10 cm of the soil, 29.5 and 23.3. per cent were found in the second and third 10 cm layers, respectively. As the mechanical resistance increased 62.9 to 67.0 per cent of the roots were found in the top 10 cm layer. The root distribution pattern in the second crop was studied by the procedure of Newman(1966). The trend of results were as for the first crop.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00672.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractImproving cotton (Gossypiumspp.) heat tolerance (ability to set bolls in high temperature environments) has been an important aspect of the American Pima (Pima) cotton (G. barbadenseL.) breeding program for over 25 years. However, heat tolerance is difficult to quantify. This report estimates change in heat tolerance of Pima cotton through yield response over 30 years in six Arizona counties that differ in elevation and mean summer temperatures. Pima cotton/upland cotton (G. hirsutumL.) lint yield percentages were compared for each county by regression with year of production. County mean yield percentages were also compared with elevations. Pima cotton yields as percentages of upland cotton yields increased in five of the six counties over the 30‐year period. Pima lint yield increased from 57 % of upland yield in 1956 to 75 % in 1985 when averaged over the six counties. This increase represents an estimated 206 kg lint ha‐1 in addition to any upland yield increase. Comparison of regression coefficients suggest that nearly 50 % of the 30‐year lint yield increase of Pima cotton at lower elevations was the result of increased tolerance to high temperature in improved cultivars. County 30‐year mean Pima cotton lint yields as percentage of upland cotton yield increased significantly (P<0.001) from 52.2% to 82.1 % as county elevations increased from 37 m to 1273 m (cooler summer temperatures). These results support reports of greater heat tolerance for upland cotton than Pima cotton, but also show that the difference between species has been reduced substantially by breeding in the last 3

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00673.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn areas where ineffective nodulation may be a problem, ‘starter’ nitrogen fertilization is often suggested as a useful management tool to sustain ineffectively nodulated seedling alfalfa (Medicago sativaL.) until an effective population ofRhizobiumcan develop. Although ineffective nodulation has been reported from several locations around the world, there have been no studies examing this possibility. A field experiment was conducted during 1982 and 1983 on a Woodburn silt loam soil (Aquultic Argixeroll) which contained a symbiotically ineffective native population ofRhizobium melilotiDang. This study examined the residual and interactive effects of preplant N fertilizer (0, 45, 90 kg N ha−1) and inoculation on the N nutrition and yield of seedling alfalfa during the first year of growth. The sustaining effects of the fertilizer N were transient and resulted in decreased N2fixation until 35 days following harvest. It was concluded that during the establishment year, managerial emphasis should be placed on inoculation and not on N fertilization to obtain a consistent, economical source of N for herbage protein and dry matter produ

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00674.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effects of different rice canopies on the temperature regime of the Azolla plants and their immediate environment were studied in a paddy field in the Philippines.Diurnal temperature cycles were measured in the field with thermocouples. Without rice plants Azolla temperature reached of up to 41°C, which was 6°C above air temperature. The rice canopy reduced the temperature of Azolla by up to 5°C. The relationship between the temperature of Azolla and of its environment (air and floodwater) is discussed. Differences between the two planting patterns of rice were obvious. With 20 × 20 cm spacing temperatures were reduced to a greater extend and at an earlier rice crop stage than with double‐narrow‐row spacing. Under extremely high temperatures the nee canopy may improve the conditions for the growth of

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00675.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA greenhouse trial was conducted with cassava inoculated with seven different VAM fungal species, i.e.Acaulospora longula, A. myriocarpa, Entrophospora colombiana, Glomus fasciculatum, G. manihotis, G. occultumandScutellospora heterogama.A wet and a dry soil water regime was established to study the effect of water stress on performance of these fungi with a drought tolerant cassava clone. At harvest, N, P and K concentration was analysed in leaves, petioles, stems and roots.In unstressed plants, five endophytes were effective whereas in stressed plants only three fungi improved growth beyond the non‐mycorrhizal control. These wereE. colombiana, G. manihotisandG. occultumwhich were most effective for P uptake under stress. Differential effects of VAM fungal species on root length and K. uptake were found.A. myriocarpacaused the greatest increase in length of feeder roots andG. occultumwas one of the most effective for K uptake under both water regimes even though these fungi were not the most effective for dry matter production. Under each water regime, the concentration of N, P and K in leaves, petioles, stems and roots was influenced by the fungal species. Mycorrhizal endophytes differed in tolerance to dry soil conditions as found by root infection ratings. From the results it can be concluded that in addition to the improved P nutrition the enhanced root length and K uptake by VAM fungi may be important for drought tolerance of cassav

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00676.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTwo cultivars of barley (Hordeum vulgareL.),Giza‐119andSahrawy, and one of soybean (Glycine max[L.] Merr.),Clarkwere subjected to osmotic stress caused by polyethylene glycol (PEG) 6000 and inoculated with ectomycorrhizal fungus;Cenococcum graniforme.PEG had stimulated growth of each barley cultivar, but not soybean. Inoculation resulted in increased shoot fresh and dry weights of soybean, either with or without PEG, and those of PEG‐stressed barley. PEG displayed a synergistic effect with mycorrhizal fungus in barley by enhancing the uptake of N, Na, K, Ca and Mg by sho

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00677.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractEffect of location, N‐fertilization, variety and harvest date on the yield of fermentable sugars of Jerusalem artichoke tops and tubersIn the past, the production of fermentable sugar with Jerusalem artichoke (Helianthus tuberosusL.) resulted nearly exclusively from tubers.It should be investigated to what extent the tops can be used beside tubers as a source of fermentable sugars, connected with studies about diverse components of yield and morphological characteristics.In field trials at three locations in the south‐west of Germany in 1983 and 1984 yields of “Total Fermentable Sugars” (TFZ) with Jerusalem artichoke tops up to 6.7 t/ha were achieved according to variety, N‐fertilization and harvest date. While harvesting Jerusalem artichoke tubers yields of TFZ up to 8.3 t/ha had been feasible.The presented correlations between components of yield and morphological plant characteristics refer to interesting mechanisms of reaction and dependence on the formation of yield with this crop. The high yield level of Jerusalem artichoke and its adaptability to different locations also present this crop as an interesting renewable biomass crop for the south‐west

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00678.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSignificant differences were observed for leaf net photosynthetic rate, chlorophyll content, soluble protein content, nitrate reductase activity, stomatal frequency and specific leaf mass among ten greengram cultivars. Leaf net photosynthetic rate had significant positive correlation with soluble protein, nitrate reductase activity, stomatal frequency and specific leaf mass. Leaf net photosynthetic rate had no relationship with leaf chlorophyll content in greengram.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1988.tb00679.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY