scholarly journals Changes in Root Anatomy of Peanut (Arachis hypogaea L.) under Different Durations of Early Season Drought

Agronomy ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 215 ◽  
Author(s):  
Nuengsap Thangthong ◽  
Sanun Jogloy ◽  
Tasanai Punjansing ◽  
Craig K. Kvien ◽  
Thawan Kesmala ◽  
...  
Keyword(s):  
Drought Resistance ◽  
Lateral Roots ◽  
Soil Surface ◽  
Vessel Diameter ◽  
Second Order ◽  
Root Anatomy ◽  
Drought Treatment ◽  
Drought Period ◽  
Early Season ◽  
Selection Of

Changes in the anatomical structure of peanut roots due to early season drought will likely affect the water acquiring capacity of the root system. Yet, as important as these changes are likely to be in conferring drought resistance, they have not been thoroughly investigated. The objective of this study was to investigate the effects of different durations of drought on the root anatomy of peanut in response to early season drought. Plants of peanut genotype ICGV 98305 were grown in rhizoboxes with an internal dimension of 50 cm in width, 10 cm in thickness and 120 cm in height. Fourteen days after emergence, water was withheld for periods of 0, 7, 14 or 21 days. After these drought periods, the first and second order roots from 0–20 cm below soil surface were sampled for anatomical observation. The mean xylem vessel diameter of first- order lateral roots was higher than that of second- order lateral roots. Under early season drought stress root anatomy changes were more pronounced in the longer drought period treatments. Twenty-one days after imposing water stress, the drought treatment and irrigated treatment were clearly different in diameter, number and area of xylem vessels of first- and second-order lateral roots. Plants under drought conditions had a smaller diameter and area of xylem vessels than did the plants under irrigated control. The ability of plants to change root anatomy likely improves water uptake and transport and this may be an important mechanism for drought tolerance. The information will be useful for the selection of drought durations for evaluation of root anatomy related to drought resistance and the selection of key traits for drought resistance.

Vegetative reproduction and root anatomy of Solanum centrale J.M.Black (Australian bush tomato)

2019 ◽  
Vol 41 (4) ◽  
pp. 345
Author(s):  
A. L. Pattison ◽  
L. W. Burgess ◽  
T. L. Bell ◽  
M. H. Ryder
Keyword(s):  
Aboriginal People ◽  
Lateral Roots ◽  
Vegetative Reproduction ◽  
South Australia ◽  
Soil Surface ◽  
Root Anatomy ◽  
Underground Structures ◽  
Mechanisms Of Formation ◽  
Root Suckering ◽  
And Function

The aim of this study was to describe the morphology, anatomy and function of underground structures associated with colonies of Solanum centrale J.M.Black (Australian bush tomato), a perennial sub-shrub found in arid areas of Australia and an important traditional staple food for Aboriginal people. It is known that this species forms clonal communities, but there is little understanding of the mechanisms of formation in either natural or cultivated situations. The underground connections within seven clonal communities from Central and South Australia were documented and samples of secondary roots, thick lateral roots and stems were examined under both laboratory and glasshouse conditions. Clonal communities were observed at all sites with individual ramets arising from lateral roots (root-suckers) that ranged from 2–10 mm in diameter growing in a network 5–15 cm below the soil surface. Lateral roots have dicotyledonous root anatomy and rapidly resprout to form new clonal ramets. They also have the capacity to accumulate starch in parenchyma cells. The morphology and root-suckering ability resemble those of weedy Solanum spp. from other parts of the world, as well as species from a variety of genera adapted to arid climates. Methods to capitalise on the ability of lateral roots to form clonal ramets in cultivated situations, particularly given the difficulties in establishing crops from seed, are discussed.

scholarly journals Selection of Second Order Models’ Design Using D-, A-, E-, T- Optimality Criteria

2019 ◽  
pp. 1-15
Author(s):  
Wangui Patrick Mwangi ◽  
Ayubu Anapapa ◽  
Argwings Otieno
Keyword(s):  
Optimality Criteria ◽  
Second Order ◽  
Factorial Designs ◽  
Economical Design ◽  
Wide Range ◽  
Eigen Value ◽  
Average Variance ◽  
Rsm Technique ◽  
Central Composite ◽  
Selection Of

There are numerous designs for fitting second order models that can be used in conjunction with the response surface methodology (RSM) technique in optimization processes, be it in agriculture, industries and so on. Some of the designs include the equiradial, Notz, San Cristobal, Koshal, Hoke, Central Composite and Factorial designs. However, RSM can only be applied in conjunction with a single design at a time. This research aimed at choosing a design out of the most widely employed designs for fitting 2nd order models involving 3 factors for optimization of French beans in conjunction with the RSM technique. The most commonly used designs for second order models were first identified as Box-Behnken designs, Hoke D2 and Hoke D6 designs, 3k factorial designs, CCD face centred, CCD rotatable and CCD spherical. Design matrices for these 7 designs were formed and augmented with 5 centre points (chosen through lottery methods), and information and optimal design matrices were formed. Then, for each design, the analysis of D-, A- E-, T- optimality (D-Determinant, A-Average Variance, E-Eigen Value and T-Trace) was carried out according to Pukelsheim’s definitions. The results were ranked for each criterion and the ranks corresponding to each design were averaged. The design chosen was Hoke D2 with the least average- 1.75. The Hoke D2 was found to be optimal in minimizing the variance of prediction and the most economical design among the seven. The findings are in agreement with other researchers and scientist that a design may be optimal in one criterion but fails in another criterion. Further, Hoke designs are in the class of the economical designs. It is recommended that more optimality criteria be applied and a wide range of designs be involved to see whether the results would still agree with these findings.

Selection of Herbicide Alternatives Based on Probable Leaching to Groundwater

1994 ◽  
Vol 8 (1) ◽  
pp. 6-16 ◽  
Author(s):  
Ralph E. Franklin ◽  
Virgil L. Quisenberry ◽  
Billy J. Gossett ◽  
Edward C. Murdock
Keyword(s):  
Coastal Plain ◽  
Partition Coefficients ◽  
Degradation Rate ◽  
Soil Surface ◽  
Computer Code ◽  
First Order ◽  
Degradation Rate Constant ◽  
And Migration ◽  
Herbicide Alternatives ◽  
Selection Of

Extension workers are sensing pressure to use soils information and chemical characteristics data to guide farmers in selecting pesticides least prone to leach into groundwater. Our objective was to estimate differences in herbicide migration to groundwater under conditions typical for the Southeast Coastal Plain, and to consider how a farmer might be advised to use such knowledge in selecting herbicides. We used a simple computer code for microcomputers to predict persistence and migration of 17 herbicides through a hypothetical, coarse-textured soil typical of the Southeast Coastal Plain. Appropriate herbicides were selected for several common crop-weed problems, such as sicklepod in soybean and Palmer amaranth in corn. Groundwater was assumed to be 3.15 m below the soil surface. Herbicides selected covered a broad range of half-lives and organic carbon partition coefficients. Only after the first-order degradation rate constant was reduced by a factor of five did predicted soil water concentrations of several herbicides at the groundwater interface reach normal detection limits. Still, predicted concentrations were below the level established for health effects advisory purposes. Due to the large number of uncertainties and the inability to estimate practical benefits, we conclude that data relating to soil and herbicide characteristics cannot be used at this time to override cost effectiveness, efficacy, and other factors normally considered by farmers and Extension professionals in herbicides for weed control.

The effects of two-body correlations in 16O on the bremsstrahlung weighted cross section

1980 ◽  
Vol 58 (8) ◽  
pp. 1099-1118
Author(s):  
D. Duplain ◽  
B. Goulard
Keyword(s):  
Cross Section ◽  
Cluster Expansion ◽  
Second Order ◽  
Body Density ◽  
The One ◽  
Selection Of

The bremsstrahlung weighted cross section σ−1, is calculated for,16O using the linked cluster expansion to introduce two-body correlations. All diagrams up to second order in the G-matrix are calculated. A particular choice is made among these diagrams which are grouped in order to preserve the normalization of the one-body density and of the two-body density. This selection of diagrams is shown to be consistent with an expansion in the number of hole-lines. The correlated value obtained in this way, σ−1 = 14.99 mb, is close to the experimental value σ−1 = 15.10 mb although the calculation might still be subject to improvement.

Effective Modal Derivatives Based Reduction Method for Geometrically Nonlinear Structures

2011 ◽  
Author(s):  
Paolo Tiso
Keyword(s):  
Reduction Method ◽  
Order Reduction ◽  
Second Order ◽  
Geometrically Nonlinear ◽  
Vibration Modes ◽  
Model Order ◽  
Modal Derivatives ◽  
Dynamics Problems ◽  
Modal Truncation ◽  
Selection Of

Effective Model Order Reduction (MOR) for geometrically nonlinear structural dynamics problems can be achieved by projecting the Finite Element (FE) equations on a basis constituted by a set of vibration modes and associated second order modal derivatives. However, the number of modal derivatives generated by such approach is quadratic with respect to the number of chosen vibration modes, thus quickly making the dimension of the reduction basis large. We show that the selection of the most important second order modes can be based on the convergence of the underlying linear modal truncation approximation. Given a certain time dependency of the load, this method allows to select the most significant modal derivatives set before computing it.

scholarly journals Plasticity of the Root System Architecture and Leaf Gas Exchange Parameters Are Important for Maintaining Bottle Gourd Responses under Water Deficit

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1697
Author(s):  
Dinoclaudio Zacarias Rafael ◽  
Osvin Arriagada ◽  
Guillermo Toro ◽  
Jacob Mashilo ◽  
Freddy Mora-Poblete ◽  
...  
Keyword(s):  
Root System ◽  
Water Deficit ◽  
System Architecture ◽  
Root Length ◽  
Leaf Gas Exchange ◽  
Lateral Roots ◽  
Physiological Responses ◽  
Root System Architecture ◽  
Second Order ◽  
Bottle Gourd

The evaluation of root system architecture (RSA) development and the physiological responses of crop plants grown under water-limited conditions are of great importance. The purpose of this study was to examine the short-term variation of the morphological and physiological plasticity of Lagenaria siceraria genotypes under water deficit, evaluating the changes in the relationship between the root system architecture and leaf physiological responses. Bottle gourd genotypes were grown in rhizoboxes under well-watered and water deficit conditions. Significant genotype-water regime interactions were observed for several RSA traits and physiological parameters. Biplot analyses confirmed that the drought-tolerant genotypes (BG-48 and GC) showed a high net CO2 assimilation rate, stomatal conductance, transpiration rates with a smaller length, and a reduced root length density of second-order lateral roots, whereas the genotypes BG-67 and Osorno were identified as drought-sensitive and showed greater values for average root length and the density of second-order lateral roots. Consequently, a reduced length and density of lateral roots in bottle gourd should constitute a response to water deficit. The root traits studied here can be used to evaluate bottle gourd performance under novel water management strategies and as criteria for breeding selection.

The Selection of the Linearized Natural Frequency for the Second-Order Normal Form Method

2011 ◽  
Author(s):  
Zhenfang Xin ◽  
S. A. Neild ◽  
D. J. Wagg
Keyword(s):  
Normal Form ◽  
Dynamic Response ◽  
Natural Frequency ◽  
Nonlinear Dynamic ◽  
Equations Of Motion ◽  
Second Order ◽  
Nonlinear Dynamic Response ◽  
Weakly Nonlinear ◽  
Selection Of ◽  
Normal Form Technique

The normal form technique is an established method for analysing weakly nonlinear vibrating systems. It involves applying a simplifying nonlinear transform to the first-order representation of the equations of motion. In this paper we consider the normal form technique applied to a forced nonlinear system with the equations of motion expressed in second-order form. Specifically we consider the selection of the linearised natural frequencies on the accuracy of the normal form prediction of sub- and superharmonic responses. Using the second-order formulation offers specific advantages in terms of modeling lightly damped nonlinear dynamic response. In the second-order version of the normal form, one of the approximations made during the process is to assume that the linear natural frequency for each mode may be replaced with the response frequencies. Here we will show that this step, far from reducing the accuracy of the technique, does not affect the accuracy of the predicted response at the forcing frequency and actually improves the predictions of sub and superharmonic responses. To gain insight into why this is the case, we consider the Duffing oscillator. The results show that the second-order approach gives an intuitive model of the nonlinear dynamic response which can be applied to engineering applications with weakly nonlinear characteristics.

scholarly journals Root and shoot attributes of indigenous perennial accessions of the wild mungbean (Vigna radiata ssp. sublobata)

2006 ◽  
Vol 57 (7) ◽  
pp. 791 ◽  
Author(s):  
G. J. Rebetzke ◽  
R. J. Lawn
Keyword(s):  
Vigna Radiata ◽  
Plant Biomass ◽  
Lateral Roots ◽  
Late Summer ◽  
Soil Surface ◽  
Sowing Date ◽  
Early Summer ◽  
Seed Biomass ◽  
Total Plant Biomass ◽  
Total Plant

Root and shoot attributes of 12 indigenous perennial accessions of the wild mungbean (Vigna radiata ssp. sublobata) were evaluated in early and late summer sowings in the field in SE Queensland. All but one of the accessions were obtained from the Townsville–Charters Towers region of NE Queensland. In both sowings, the accessions developed thickened tap and lateral roots, the taproot thickening extending to a depth of 0.20–0.30 m below the soil surface, depending on accession. The thickened lateral roots emerged from the taproot within 0.10 m of the soil surface, and extended laterally up to 1.10 m, remaining close to the soil surface. Differences among the accessions in gross root morphology and phenology were relatively small. There were differences among the accessions in the production of seed, tuberised root, and recovered total plant biomass. Depending on accession and sowing date, the tuberised roots accounted for up to 31% of recovered plant biomass and among accessions, the root biomass was positively correlated with total plant biomass. In contrast, seed biomass represented only a small proportion of recovered plant biomass, up to a maximum of 14%, depending on accession and sowing date. Among accessions, the proportion of seed biomass tended to be negatively correlated with that of tuber biomass. The perennial trait appears to be unique to Australian accessions of wild mungbean obtained from coastal-subcoastal, speargrass-dominant woodlands of NE Queensland. Although the ecological significance of the trait remains conjectural, field observation indicates that it facilitates rapid plant re-growth following early summer rainfall, especially where dry-season fire has removed previous-season above-ground growth.

Tree climbing by the snail Cepaea nemoralis (L.): a possible method for regulating temperature and hydration

1979 ◽  
Vol 57 (5) ◽  
pp. 1010-1014 ◽  
Author(s):  
Renata Jaremovic ◽  
C. David Rollo
Keyword(s):  
Habitat Structure ◽  
Soil Surface ◽  
Daily Temperature ◽  
Maximum Daily Temperature ◽  
Cepaea Nemoralis ◽  
Color Morphs ◽  
Selection Of

Three sheltering strategies employed by the snail Cepaea nemoralis are described: climbing objects, aestivating on the soil surface, and returning to underground refuges. The number of snails that climbed bushes was analysed by correlation regression. An equation incorporating maximum daily temperature, rainfall for the last 3 days, and the interaction of these factors explained 95% of the variation observed (P < 0.0001). Snails more than 1.8 m above the ground were significantly more dehydrated than those individuals found lower (P < 0.05). The distance climbed by snails, however, was not related to their size (P = 0.4112). The interrelationship of habitat structure, sheltering behavior, and microclimate is discussed in relation to selection of color morphs.

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