The effect of temperature on the field softening of hard seed of Stylosanthes humilis and S. hamata in a dry monsoonal climate

1982 ◽  
Vol 33 (1) ◽  
pp. 75 ◽  
Author(s):  
GM McKeon ◽  
JJ Mott
Keyword(s):  
Management Practices ◽  
Soil Surface ◽  
Field Studies ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Hard Seed ◽  
Surface Temperatures ◽  
Stylosanthes Humilis ◽  
One Year ◽  
Field And Laboratory Conditions

The changes in hard-seed content in pastures of Stylosanthes humilis and S. hamata cv. Verano were studied at Katherine, N.T. Both field studies and laboratory ovens with diurnal temperature changes showed that maximum soil surface temperatures greater than 50-55�C were required to produce substantial softening of hard seed. The rate of softening increased with higher maximum temperature. At Katherine, only the September-November period (late dry season) was likely to produce soil surface temperatures high enough for softening in naturally occurring seed populations. S. hamata did not soften to the same extent as S. humilis under both field and laboratory conditions. In established pastures only 35 % of S. hamata seed softened in one year, compared with 60-80% in S. humilis. Management practices may be required to improve seedling regeneration or establishment of new pastures in S. hamata.

Effect of Temperature on the Synthesis of Jojoba Wax

1985 ◽  
Vol 12 (4) ◽  
pp. 355 ◽  
Author(s):  
RL Dunstone ◽  
A Benzioni ◽  
ML Tonnet ◽  
P Milthorpe ◽  
A Shani
Keyword(s):  
Field Studies ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Wax Ester ◽  
Controlled Environment ◽  
Percentage Elongation ◽  
Jojoba Wax ◽  
Seed Growth ◽  
The Mean ◽  
Long Chain

Seed was collected from jojoba [Simmondsia chinensis (Link) Schneider] plants growing at three field sites in two years. The wax percentage was determined by nuclear magnetic resonance and the compositions of the wax and the ethanolysis products (one site only) were determined by gas chromatography. The mean wax concentration varied from 49.2 to 55.1% over all sites and years. The percentage of long-chain wax esters (>C40) decreased linearly with increase in mean maximum temperature during the period of linear seed growth (r� = 0.93). The decrease in long-chain esters was associated with a decrease in the C22 and C24 fatty acids and alcohols. Data from controlled environment studies and from field studies were used to assess the effect of temperature on the percentage elongation, reduction and esterification of acyl-CoAs of carbon lengths 18-22. High temperature lowered the specificity for elongation of C20-C22 and of C22-C,24 and increased the specificity for reduction of the C20 acid to its corresponding alcohol. The amount of C42 wax ester was greater than would be expected by random association of the alkoxy-acyl groups but this preference was not as great at high temperatures.

Itchgrass (Rottboellia cochinchinensis) Control Options in Soybean (Glycine max)

1991 ◽  
Vol 5 (2) ◽  
pp. 426-429 ◽  
Author(s):  
James L. Griffin
Keyword(s):  
Glycine Max ◽  
Soil Surface ◽  
Field Studies ◽  
Late Season ◽  
Control Options ◽  
One Year ◽  
Rottboellia Cochinchinensis

In field studies trifluralin and pendimethalin at 1.7 kg ai ha-1applied PPI controlled itchgrass 87 and 78%, respectively, in late season when averaged over a 2-yr period. Clomazone at 1.1 kg ai ha-1applied PRE to the soil surface in one year controlled 80% of itchgrass compared with 51% when applied PPI. POST application of 0.15 kg ai ha-1fluazifop-P, 0.21 kg ai ha-1haloxyfop, 0.10 kg ai ha-1quizalofop, and 1.1 kg ai ha-1diclofop controlled at least 90%. Itchgrass control was less effective with 0.43 kg ai ha-1sethoxydim and 0.07 kg ai ha-1clethodim POST and poor with 0.15 kg ai ha-1imazaquin and 0.07 kg ai ha-1imazethapyr.

Effect of Temperature on Time from Planting to Flowering in Virginia Type Peanuts (Arachis hypogaea L.)1

1974 ◽  
Vol 1 (2) ◽  
pp. 86-90 ◽  
Author(s):  
F. R. Cox ◽  
C. K. Martin
Keyword(s):  
Empirical Relation ◽  
Mathematical Expression ◽  
Field Studies ◽  
Linear Functions ◽  
Quadratic Functions ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Daily Maximum ◽  
Heat Unit ◽  
The Individual

Abstract Field studies with a planting date variable were utilized to determine an empirical relation between time from planting to first flowering of NC2, NC5, and Florigiant peanuts and minimum and maximum daily temperatures. Two basic types of curvilinear response functions and two heat unit systems, which used linear functions, were compared on the basis of days missed by each prediction. The mathematical expression of the data that gave the least days missed was the daily fraction of time to flowering being the sum of quadratic functions for minimum and maximum temperature. The rate of slope change was greater at the higher end of the temperature range. The relation between time to flowering and minimum temperature was more curvilinear that that for maximum temperature except at higher temperatures. Minimum temperatures below 43° F lengthened the time to flowering for the three varieties. Varietal differences appeared to be expressed more by the relation with daily maximum than with daily minimum temperatures. The expressions calculated should be more accurate for prediction purposes than a linear heat unit system, plus they tend to describe the individual responses to changes in minimum and maximum temperatures. A certain lack of fit for the relation still exists, indicating perhaps some other measure, such as solar radiation, should also be included.

scholarly journals Mineralisation, leaching and stabilisation of <sup>13</sup>C-labelled leaf and twig litter in a beech forest soil

2011 ◽  
Vol 8 (1) ◽  
pp. 1043-1076
Author(s):  
A. Kammer ◽  
F. Hagedorn
Keyword(s):  
Leaf Litter ◽  
Mineral Soil ◽  
Soil Surface ◽  
Field Studies ◽  
Beech Forest ◽  
Organic C ◽  
C Storage ◽  
C Stocks ◽  
Mineral Soils ◽  
One Year

Abstract. Very few field studies have quantified the different pathways of C loss from decomposing litter even though this is essential to better understand long-term dynamics of C stocks in soils. Using 13C-labelled leaf (isotope ratio (δ13C) = −40.8‰) and twig litter (δ13C = −38.4‰), we tracked down the litter-derived C in the soil respiration, in the dissolved organic C (DOC) and in the soil organic matter of a beech forest in the Swiss Jura. After one year of decomposition, mass loss in the litter layer was almost twice as great for leaves as it was for twigs (75% vs. 40%). This difference was not the result of a slow mineralisation of the woody litter, but primarily of the only slight incorporation of twig-derived C into mineral soils. The C mineralisation rates of the twig litter were only slightly lower than those of the leaf litter (10–35%), in particular after the loss of the readily available litter fraction. However, the leaching of DOC from twigs amounted only to half of that from leaves. Tracing the litter-derived DOC showed that DOC from both litter types was mostly retained (88–96%) and stabilised in the top centimetres of the mineral soil. In the soil organic C at 0–2 cm depth, we recovered 8% of the initial leaf C, but only 4% of the twig C. Moreover, the 13C mass balance suggested that a substantial fraction of the leaf material (~30%) was transported via soil fauna to soil depths below 2 cm, while the twig litter mainly decomposed in situ on the soil surface, probably due to its rigid structure and low nutritional value. In summary, our study shows that decaying twigs are rapidly mineralised, but seem to be clearly less important for the C storage in this beech forest soils than leaf litter.

scholarly journals Willows Used for Phytoremediation Increased Organic Contaminant Concentrations in Soil Surface

2021 ◽  
Vol 11 (7) ◽  
pp. 2979
Author(s):  
Maxime Fortin Faubert ◽  
Dominic Desjardins ◽  
Mohamed Hijri ◽  
Michel Labrecque
Keyword(s):  
Soil Surface ◽  
Field Work ◽  
Field Studies ◽  
Soil Hydrology ◽  
Intensive Culture ◽  
Shrub Species ◽  
Short Rotation ◽  
Pollutant Concentrations ◽  
Polycyclic Aromatic ◽  
Made In

The Salix genus includes shrub species that are widely used in phytoremediation and various other phytotechnologies due to their advantageous characteristics, such as a high evapotranspiration (ET) rate, in particular when cultivated in short rotation intensive culture (SRIC). Observations made in past field studies suggest that ET and its impact on soil hydrology can also lead to increases in soil pollutant concentrations near shrubs. To investigate this, sections of a mature willow plantation (seven years old) were cut to eliminate transpiration (Cut treatment). Soil concentrations of polychlorinated biphenyls (PCBs), aliphatic compounds C10–C50, polycyclic aromatic hydrocarbons (PAHs) and five trace elements (Cd, Cr, Cu, Ni and Zn) were compared between the Cut and the uncut plots (Salix miyabeana ‘SX61’). Over 24 months, the results clearly show that removal of the willow shrubs limited the contaminants’ increase in the soil surface, as observed for C10–C50 and of 10 PAHs under the Salix treatment. This finding strongly reinforces a hypothesis that SRIC of willows may facilitate the migration of contaminants towards their roots, thus increasing their concentration in the surrounding soil. Such a “pumping effect” in a high-density willow crop is a prominent characteristic specific to field studies that can lead to counterintuitive results. Although apparent increases of contaminant concentrations contradict the purification benefits usually pursued in phytoremediation, the possibility of active phytoextraction and rhizodegradation is not excluded. Moreover, increases of pollutant concentrations under shrubs following migration suggest that decreases would consequently occur at the source points. Some reflections on interpreting field work results are provided.

General practitioners and clinical pharmacology

1989 ◽  
Vol 4 (4) ◽  
pp. 241-244
Author(s):  
P. Lemoine
Keyword(s):  
Clinical Pharmacology ◽  
General Practitioners ◽  
Field Studies ◽  
Discussion Group ◽  
Group Method ◽  
Study Group ◽  
Test Drug ◽  
Monthly Basis ◽  
One Year ◽  
The One

SummaryIt is difficult to undertake field studies with non marketed psychotropic drugs because of two apparently contradictory conditions : on the one hand, the methodology has to be rigorously controlled, and on the other hand, such studies have to be carried out in their future environment by general practitioners (GPs). Bearing in mind the lack of training and experience regarding this kind of approach, the author adopted a discussion group method according to the techniques developed by M. Balint. The study group comprised five GPs, a clinical pharmacology expert and a doctor from the pharmaceutical laboratory which had developed the test drug. These persons met on a monthly basis over a one year period. In the present paper, the author indicates the benefits of such a methodology, based on six years’ experience and several trials, with special emphasis placed on the pedagogical aspects.

scholarly journals Evaluation of Image-Based Phenotyping Methods for Measuring Water Yam (Dioscorea alata L.) Growth and Nitrogen Nutritional Status under Greenhouse and Field Conditions

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 249
Author(s):  
Emmanuel Frossard ◽  
Frank Liebisch ◽  
Valérie Kouamé Hgaza ◽  
Delwendé Innocent Kiba ◽  
Norbert Kirchgessner ◽  
...  
Keyword(s):  
Management Practices ◽  
Leaf Surface ◽  
Plant Traits ◽  
Soil Surface ◽  
Shoot Biomass ◽  
N Content ◽  
Total Leaf ◽  
Image Pixels ◽  
Leaf N Content ◽  
Yield Formation

New management practices must be developed to improve yam productivity. By allowing non-destructive analyses of important plant traits, image-based phenotyping techniques could help developing such practices. Our objective was to determine the potential of image-based phenotyping methods to assess traits relevant for tuber yield formation in yam grown in the glasshouse and in the field. We took plant and leaf pictures with consumer cameras. We used the numbers of image pixels to derive the shoot biomass and the total leaf surface and calculated the ‘triangular greenness index’ (TGI) which is an indicator of the leaf chlorophyll content. Under glasshouse conditions, the number of pixels obtained from nadir view (view from the top) was positively correlated to shoot biomass, and total leaf surface, while the TGI was negatively correlated to the SPAD values and nitrogen (N) content of diagnostic leaves. Pictures taken from nadir view in the field showed an increase in soil surface cover and a decrease in TGI with time. TGI was negatively correlated to SPAD values measured on diagnostic leaves but was not correlated to leaf N content. In conclusion, these phenotyping techniques deliver relevant results but need to be further developed and validated for application in yam.

Seed dormancy in four Tibetan Plateau Vicia species and characterization of physiological changes in response of seeds to environmental factors

2013 ◽  
Vol 23 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Xiaowen Hu ◽  
Tingshan Li ◽  
Juan Wang ◽  
Yanrong Wang ◽  
Carol C. Baskin ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Seed Dormancy ◽  
Germination Rate ◽  
Soil Surface ◽  
The Tibetan Plateau ◽  
Physical Dormancy ◽  
High Germination ◽  
One Year ◽  
Hydrotime Model ◽  
Aba Biosynthesis

AbstractAlthough seed dormancy of temperate legumes is well understood, less is known about it in species that grow in subalpine/alpine areas. This study investigated dormancy and germination of four Vicia species from the Tibetan Plateau. Fresh seeds of V. sativa were permeable to water, whereas those of V. angustifolia, V. amoena and V. unijuga had physical dormancy (PY). One year of dry storage increased the proportion of impermeable seeds in V. angustifolia, but showed no effect on seed coat permeability in V. amoena or V. unijuga. Seeds of all four species also had non-deep physiological dormancy (PD), which was especially apparent in the two annuals at a high germination temperature (20°C). After 1 year of storage, PD had been lost. The hydrotime model showed that fresh seeds obtained a significantly higher median water potential [Ψb(50)] than stored seeds, implying that PD prevents germination in winter for seeds dispersed without PY when water availability is limited. After 6 months on the soil surface in the field, a high proportion of permeable seeds remained ungerminated, further suggesting that PD plays a key role in preventing germination after dispersal. Addition of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis, evened-out the differences in germination between fresh and stored seeds, which points to the key role of ABA biosynthesis in maintaining dormancy. Further, fresh seeds were more sensitive to exogenous ABA than stored seeds, indicating that storage decreased embryo sensitivity to ABA. On the other hand, the gibberellic acid GA3 increased germination rate, which implies that embryo sensitivity to GA is also involved in seed dormancy regulation. This study showed that PY, PD or their combination (PY+PD) plays a key role in timing germination after dispersal, and that different intensities of dormancy occur among these four Vicia species from the Tibetan Plateau.

scholarly journals Prediction of leaching and groundwater contamination by pesticides

2006 ◽  
Vol 78 (5) ◽  
pp. 1081-1090 ◽  
Author(s):  
Werner Kördel ◽  
Michael Klein
Keyword(s):  
Maximum Concentration ◽  
Management Practices ◽  
Preferential Flow ◽  
Soil Depth ◽  
Sandy Soils ◽  
Field Studies ◽  
Macropore Flow ◽  
Eu Directive ◽  
Present Information ◽  
Silty Soils

Herein, we describe how pesticide leaching is assessed in Europe in order to fulfill EU Directive 91/414. The assessment schemes were developed to protect groundwater from unacceptable effects caused by pesticide use. They presently focus on chromatographic flow processes, which are dominant in sandy soils. Nevertheless, important regions in Europe are characterized by structured soils where transport through macropores is most relevant.Comparison of parallel field studies with isoproturon performed in sandy and silty soils showed that maximum concentration in the structured soil at a soil depth of 1 m may exceed respective concentrations in sandy soils by a factor of 60. Similar results were obtained by lysimeter studies using silty soil cores with maximum concentration of 40 μg/l at the soil bottom. These results demonstrate that preferential flow is more the rule than the exception in well-structured fine-textured soils, and pesticide losses via macropore flow may exceed losses via matrix transport considerably. All present information available for macropore flow suggest the need for greater regional assessments. Other recommendations include analysis of the influence of different soil management practices on the formation of macropores.

scholarly journals Thermoregulation in colonies of africanized and hybrids with Caucasian, Italian and Carniolan Apis mellifera honey bees

1999 ◽  
Vol 42 (4) ◽  
Author(s):  
Vagner de Alencar Arnaut de Toledo ◽  
Regina Helena Nogueira-Couto
Keyword(s):  
Apis Mellifera ◽  
Honey Bees ◽  
Maximum Temperature ◽  
Tropical Region ◽  
Internal Temperature ◽  
Africanized Honey Bees ◽  
Significant Difference ◽  
The Mean ◽  
One Year ◽  
Brood Nest

This experiment was carried out to study the internal temperature regulation of a colony of Africanized honey bees (AFR), compared with hybrid Caucasian (CAU), Italian (ITA), and Carniolan (CAR) bees, during the period of one year and different size hives located in a sub-tropical region. The instant internal temperature, 33.7 ± 1.5° C for the AFR, 33.5 ± 1.4° C for the CAU, 33.7 ± 1.5° C for the ITA and 33.8 ± 1.4° C for the CAR, did not show any significant difference (P>0.05). The maximum temperature (36.1 ± 2.3° C) was statistically different (P<0.05) from the minimum (27.6 ± 5.3° C). There was no difference (P>0.05) in the mean internal temperature, between the nucleus (31.7 ± 6.3° C) and the brood nest (32.1 ± 5.3° C) measured between two and four o'clock in the afternoon.

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