摘要:

AbstractModel trials on the uptake of soil and fertilizer nitrogen from various depths by spring wheatThe uptake of ammonium nitrogen by spring wheat mixed into various soil depths was investigated in a pot trial using 1‐m high soil columns. At the same time a nitrification inhibitor (NI) was used in some of the variants in order to study the utilization of fertilizer N under the conditions of a temporary inhibition of nitrification. In order to monitor the interrelationships of soil and fertilizer N,15N‐labelled ammonium sulphate was used. The following results were obtained.1The various depths at which the N was located were not found to affect yields; nor did the use of the NI have any influence.2There was a statistically significant increase in the N content of the grains as the N was mixed with deeper layers of the soil; this was at a lower level in the series with NI. In straw no change was observed in the series without NI, there being a decrease of the N content in the series with NI.3The utilization of fertilizer N according to the “difference method” was between 76 % and 84 % in the series without NI with an increasing tendency of the nitrogen located at deeper levels. In the series with NI there was a reverse tendency of 74 % to 69 %. According to the 15N method only 54–62 % of the fertilizer N was used by the plants. The NI scarcely changed the utilization. Overall there was not a significant higher use of the nitrogen in the deeper layers.4In the fertilized series more soil N was mobilized and taken up by the plants than in the control. This effect was more pronounced in the series with no NI.5The mobilization of soil N by fertilizer N (“priming effect”) contrasted with a more vigorous immobilization of fertilizer N. This resulted in an overall positive soil N balance.6A total of about 30 % of the fertilizer N remained in the soil. Most of it was to be found in the incorporation layer. However, displacement into the neighbouring layers did take place, this being more pronounced in the acropetal direction in the case of the N in the deeper layers than in the basipetal direction in the case of the N introduced into

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00079.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractResponse of maize inbred lines and hybrids to increasing rates of nitrogen fertilizerThe response of 8 flint and 8 dent inbred lines and 16 flint × dent single crosses to three rates of nitrogen fertilizer (80, 160, 240 kg/ha) were tested in the years 1983 and 1984 in field trials at one location. The material represents a broad range of maize genotypes not strongly selected for kernel yield.The mean kernel yield of all hybrids increased from the lowest to the medium N treatment by 7.6 % in 1983 and by 4.9 % in 1984. The highest fertilizer level resulted in an additional yield advantage in the two years of 6.1 % and 4.4 % respectively. An increased nitrogen rate had a positive effect on plant height, leaf area index, grains/cob, 1000 kernel weight, and protein content. Lodging resistance and dry matter content were not significantly influenced by N treatments. A significant interaction between genotype and N treatment was observed for leaf area index, 1000 kernel weight, and protein content, but not for kernel yield. The correlations of kernel yield with other traits investigated were not consistent over years and nitrogen treatments

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00080.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractExperiment conducted with six pigeonpea cultivars over three seasons revealed that the critical leaf area index was 5.3 which coincided with the maximum crop growth rate and optimum net assimilation rate. It was also evident that the crop growth rate was influenced more by NAR rather than LAI. This study also suggests that by maintaining higher photosynthesis upto harvest, there is ample possibility to increase the crop growth rate till harvest.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00081.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractLittle is known of the relationship between hybrids and parental material with respect to water use and drought resistance. Responses of sorghum (Sorghum bicolor[L.] Moench) F1hybrids to moisture deficits are partially determined by parental material. The yield and water use of six sorghum hybrids and their respective male and female parents were evaluated under stressed and well irrigated conditions during 1980 and 1981 at Tucson, Arizona. The soil was Comoro loamy sand (coarse‐loamy, mixed, calcareous, thermic typic Torrifluvent) with an average available soil moisture of 16 % at field capacity.Changes in soil moisture were monitored semi‐weekly by neutron modulation. Meteorological data were collected daily. The 1980 season had higher maximum temperatures and pan evaporation than the 1981 season. Differences in cumulative water use among entries were apparent within the same water treatments during 1981. Mean cumulative evapotranspiration (ET) for the stressed treatment was 248 and 281 mm for 1980 and 1981, respectively, and ET under well irrigated conditions was 419 and 528 mm for 1980 and 1981, respectively.Hybrids produced greater grain yield than their parents under both water treatments. This was due to greater seed number for hybrids. Seed numbers were more stable for hybrids over both treatments than for parents. Hybrids four and seven had the greatest grain yield in 1980 and 1981, respectively, under stressed conditions. Water use efficiency (WUE) was significantly different within water treatments but was not so between the irrigated and stressed treatments. Hybrids WUE was generally greater than that of parents except for hybrid five under irrigated conditions in 1981. Hybrids with WUE and stable yields were not necessarily reflective of parental material under stressed and non‐stressed environ

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00082.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractField experiments were conducted for four years (1981 to 1984) at Lexington, KY, USA (38° N latitude) to determine the causes of reduced yields associated with delayed plantings of soybean (Glycine max[L.] Merrill). Five cultivars were planted in mid‐May and early July in row spacings ranging from 18 to 89 cm and the plots were irrigated to minimize moisture stress. Yields were significantly reduced by delayed planting because of reductions in the number of seed m−2and mass seed−1. The yield reduction under irrigation indicates that moisture stress is not a major cause of reduced yields from delayed plantings. The reductions in seed number were associated with lower insolation interception during flowering and pod set and with smaller vegetative mass (g m−2) at growth stage R5 (beginning seed fill). The data suggest that a vegetative mass at R5 greater than that required to intercept 90 % or more of incident insolation is required to maximize seed number. The length of the seed filling period was not affected by planting date. Mass seed−1was positively related to mean air temperature during seed filling, which suggests that the smaller seed from delayed plantings are a result of the lower temperatures associated with the late

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00083.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractInfiltrability of various soybean and maize rotations under conventional tillage and no‐tillage was studied to evaluate these rotations with respect to soil conservation practices. Measurements were carried out with a rainfall simulator on an Oxisol in two trials in northern Paraná, Brazil.Differences between rotations were greatest in the conventional tillage treatments and here maize/soybean rotations showed a higher infiltrability than continuous cropping. In the no‐tillage treatments, there were hardly any significant differences. On the whole, rotations grown with maize at the time of measurement resulted in the lowest infiltrabilities. Tillage effects were of greater importance than rotation effects, infiltrability being consistently highest under no‐tillage.Soil surface sealing in dependence of the degree of soil cover was shown to be the prime factor governing infiltra

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00084.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractPearl millet (Pennisetum americanum[L.] Leeke) and sorghum (Sorghum bicolor[L.] Moench) can suffer from poor stand establishment under conditions of high soil temperature and water stresses. A line source sprinkler irrigation system and a charcoal pit technique were used to evaluate stand establishment and high correlations existed between the two methods. It may be possible to use the charcoal pit technique as a predictive tool in drought resistance breeding programs.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00085.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractPhosphorus and ammonium nitrogen placed together has been shown to increase P uptake by crops, especially cereals, Thus, the objective of this study was to compare this effect on four crops grown in Manitoba. Plants harvested at flowering indicated greater P uptake in lentils, soybean and wheat, when P and NH4+‐N were placed on the same band. In contrast, canola did not respond to this treatment. Possible relationships of these ions are presente

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00086.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractChemical manipulation was able to induce higher productivity in soybean through improved dry matter accumulation, increased source activity, retarding leaf senescence and yield components. The senescence percentage was negatively correlated with yield (r =−0.7669**) while the source activity was positively associated (r =+0.9167**). All the yield components had significant positive correlation with yield. The low cost urea and coconut water, foliar feeding at peak flowering and late grain filling stages improved the productivity in soybean. The maximum beneficial effect of foliar feeding was noticed in the soil where the absence of native nodulation was observe

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00087.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractField experiments were conducted at the Livestock Research Centre of G.B. Pant University of Agriculture and Technology, Pantnager, India during wet season (June‐September) of 1978 with the objectives of characterizing canopy and seasonal profiles ofin vivonitrate reductase activity (NRA) of grain sorghum (Sorghum bicolor[L.] Moench) cultivars.Canopy profile of NRA was studied on hybrid CSH 5 at 45, 55, 70, 80 and 95 days after sowing, whereas seasonal profile of NRA was studied in six sorghum cultivars — hybrid CSH 5 and pure line varieties CSV 4, SPV 100, SPV 101, SPV 103 and SPV 106 beginning at 30 days until 95 days after sowing.Canopy profile studies indicated that fully expanded recently matured leaves possessed higher levels ofin vivoNRA than unexpanded immature as well as older leaves. Seasonal profiles ofin vivoNRA showed different trends in different cultivars. Cultivars SPV 100, SPV 101, SPV 103 and SPV 106 demonstrated two peaks ofin vivoNRA/plant/day at 44 and 95 days. On the other hand, hybrid CSH‐5 had only one peak at 51 days and cultivar CSV 4 had

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1987.tb00088.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY