scholarly journals SAFETY AND EFFICIENCY OF XYLEM WATER TRANSPORT IN TWO CASHEW (Anacardium occidentale L.) STRAINS AT THE SEEDLING STAGE

2020 ◽  
Vol 18 (4) ◽  
pp. 156
Author(s):  
JOKO PITONO ◽  
TSUDA MAKOTO
Keyword(s):  
High Pressure ◽  
Water Transport ◽  
Applied Pressure ◽  
Vessel Diameter ◽  
Hydraulic Conductance ◽  
Seedling Stage ◽  
Wet Season ◽  
Flow Meter ◽  
Pressure Flow ◽  
Xylem Vulnerability

<p>ABSTRACT<br />As cashew trees are grown by transplanting seedlings, the seedling<br />often suffers from drought damaged due to prolonged dry season. Previous<br />study found that the ability to maintain water transport in xylem related to<br />drought resistant character. To determine whether there was trade-off<br />between the ability to maintain water transport in xylem and an efficiency<br />of water transport, differences in xylem vulnerability to dysfunction,<br />hydraulic conductance, and the relationship to xylem vessel diameter were<br />examined in two cashew strains. The xylem vulnerability to dysfunction<br />was evaluated by the applied pressure which induced 50% loss of stem<br />hydraulic conductivity (P 50 ). The hydraulic conductance on root, stem, and<br />leaf were determined with High Pressure Flow Meter (HPFM). Variations<br />in the P 50 values were found between A3-1 and Pangkep, whereas the<br />values were 1.75 and 0.50 MPa, respectively. However, since there was no<br />difference in the hydraulic conductance and the vessel diameter, the trade-<br />off between the ability to maintain water transport in xylem and an<br />efficiency of water transport did not occur in cashew. It was suggested that<br />good combination of efficiency and safety of water transport enables A3-1<br />to strongly uptake soil water either in dry or wet season resulting in good<br />adaptation to drought prone environment, and the P 50 value would be<br />suitable parameter for evaluating drought tolerance of cashew at the<br />seedling stage.<br />Key words: cashew strain, vessel, xylem dysfunction, hydraulic<br />conductance, drought</p><p>ABSTRAK<br />Pengembangan jambu mete secara transplanting sering diikuti<br />cekaman kekeringan pada bibit akibat musim kering yang berkepanjangan.<br />Studi awal memperlihatkan bahwa kemampuan xylem mempertahankan<br />fungsi transportasi air merupakan karakter pertahanan penting terhadap<br />cekaman kekeringan. Untuk mengetahui apakah terjadi kompensasi antara<br />kemampuan pertahanan fungsi xylem dan tingkat efisiensi transportasi<br />airnya dilakukan pengujian pada aspek kepekaan fungsi xylem, hantaran<br />hidraulik, dan ukuran vesselnya. Kepekaan fungsi xylem ditentukan dari<br />nilai tekanan udara yang menyebabkan kehilangan 50% hydraulic<br />conductance (P 50 ). Nilai hydraulic conductance pada akar, batang, dan<br />daun ditentukan dengan menggunakan metode High Pressure Flow Meter<br />(HPFM). Hasil pengujian menunjukkan terdapat perbedaan nilai P 50<br />diantara dua strain jambu mete yang diuji, yakni secara berturut-turut 1,75<br />dan 0,50 MPa pada strain A3-1 dan Pangkep. Karena tidak disertai<br />perbedaan pada hydraulic conductance dan ukuran vesselnya, maka<br />disimpulkan tidak ditemukan nilai adanya mekanisme kompensasi antara<br />kemampuan pertahanan fungsi xylem dan tingkat efisiensi pengangkutan<br />air. Hal ini memungkinkan A3-1 tetap dapat menyerap air tanah secara<br />cukup, baik pada musim kering maupun musim basah, dan mampu<br />beradaptasi dengan baik di daerah rawan kekeringan. Dan nilai P 50 dapat<br />dijadikan sebagai parameter representatif untuk evaluasi toleransi bibit<br />jambu mete terhadap cekaman kekeringan.<br />Kata kunci:  strain jambu mete, vessel, fungsi xylem, hydraulic<br />conductance, cekaman kekeringan</p>

scholarly journals Influence of hydraulic properties of rootstocks and the rootstock-scion graft on water use and productivity of apple trees

2001 ◽  
Author(s):  
Shabtai Cohen ◽  
Melvin Tyree ◽  
Amos Naor ◽  
Alan N. Lakso ◽  
Terence L. Robinson ◽  
...  
Keyword(s):  
High Pressure ◽  
Water Transport ◽  
Hydraulic Conductance ◽  
Leaf Conductance ◽  
Leaf Water ◽  
Graft Union ◽  
Large Trees ◽  
The Us ◽  
Before And After ◽  
Dwarfing Rootstocks

This one year exploratory project investigated hydraulic architecture of apple dwarfing rootstocks. The hypothesis was that hydraulic conductance is correlated with rootstock vigor. A previous study of trees on three rootstocks in Israel showed that dwarfed trees used less water than un-dwarfed trees. Analysis showed that if the tree maintains leaf water potentials above minimum values, then this implies that the dwarfed trees have lower leaf conductance, which may also be the cause of dwarfing. The current project studied small 2-year old unworked rootstock trees, and full sized trees bearing commercial yields. In both cases hydraulic conductance was determined with two methods - the non-destructive evaporative flux (EF)-leaf water potential (L WP) method, and a destructive method in which water was forced through the plant at known pressure using the "high pressure flow meter" (HPFM). Detailed work allowed measurement of conductance of the rootstock-scion union. This was achieved both with the HPFM and with the EF-LWP methods, the former in the US and the latter in Israel. Direct measurements of leaf conductance were made, and carbon isotope ratios ( d ¹³ C) were determined for leaves sampled at the end of the season. The latter can indicate sustained differences in leaf conductance behavior. HPFM and EF-LWP methods did not give the same results. In the small plants results were similar in magnitude, but not significantly correlated. In large trees, EF- L WP measurements were a fraction of those obtained with the HPFM. The latter indicates that some of the xylem is not normally functional but transports water when pressurized. Additional experimental work targeted this result. Xylem was stained before and after perfusion with water at high pressure. This showed that at least for one rootstock a significant amount of xylem was blocked before perfusion. The "air method" for determining xylem vessel properties was improved and employed. Length, radius and density of xylem vessels of different rootstocks were found to be similar, and significant differences found were not clearly related to rootstock vigor. Measurements in the commercial orchard in Israel showed that the graft union in a dwarfing rootstock was a large obstacle for water transport (i.e. had a high resistance). This apparently led to low leaf conductance to water vapor, as indicated by lower d ¹³ C, which implies low internal CO ₂ concentrations. In the US orchard, d ¹³ C in 2001 was correlated with rootstock vigor, and significant differences were found in leaf conductance. However, the d ¹³ C differences were not observed in 2002, were opposite to those found in the Israeli orchard, and measurements of the graft union with the HPFM did not find large resistances. We speculate that the graft union is not necessarily a large impediment to water transport unless the scion starts to separate from the rootstock. It was concluded that significant differences in hydraulic conductance exist between different dwarfing rootstocks. These differences may be caused by differences in xylem properties and in the degree of cavitation, as well as resistance in the graft union. However, no general relationship to rootstock vigor was found. Therefore, hydraulic conductance alone cannot explain dwarfing, but may be one of two or more factors that lead to dwarfing. Future work should integrate more factors with hydraulic relations, e.g. nutrient and solute transport and production of hormones.  

Measuring plant hydraulic conductance and xylem vulnerability under close to natural conditions

2020 ◽  
Author(s):  
Louis Krieger ◽  
Stanislaus Schymanski
Keyword(s):  
Water Transport ◽  
Common Factor ◽  
Hydraulic Conductance ◽  
Pressure Gradients ◽  
Natural Conditions ◽  
Flow Meters ◽  
Xylem Vulnerability ◽  
Large Pressure ◽  
Low Pressures

&lt;p&gt;Usually hydraulic conductance and vulnerability are measured under extreme conditions never experienced by living plants (e. g. centrifugation, bench dehydration, and large pressure gradients). A common factor that is known to inhibit the water transport in plants is cavitation, which is believed to occur either by air entry through the pit valves on the walls of the xylem, or by ex-solution of dissolved gases, or vaporization of water at very low pressures. Various physical characteristics of the xylem influence the efficiency of transport and the vulnerability to cavitation.&lt;/p&gt;&lt;p&gt;Here we explore possibilities to measure hydraulic conductance and induce cavitation under close to natural conditions. We designed a very simple &amp;#8220;artificial plant&amp;#8221; consisting of a root and a transpiring membrane, equipped with pressure and flow meters, where a twig can be inserted in the flow path to measure its hydraulic conductance. Attempts to induce cavitation resulted in surprising results, provoking new questions on the role of xylem structural traits and their relevance for water transport in plants.&lt;/p&gt;

scholarly journals Ethylene enhances root water transport and aquaporin expression in trembling aspen (Populus tremuloides) exposed to root hypoxia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiangfeng Tan ◽  
Mengmeng Liu ◽  
Ning Du ◽  
Janusz J. Zwiazek
Keyword(s):  
Gas Exchange ◽  
Water Transport ◽  
Populus Tremuloides ◽  
Leaf Gas Exchange ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Trembling Aspen ◽  
Expression Levels ◽  
Root Hypoxia ◽  
Exogenous Ethylene

Abstract Background Root hypoxia has detrimental effects on physiological processes and growth in most plants. The effects of hypoxia can be partly alleviated by ethylene. However, the tolerance mechanisms contributing to the ethylene-mediated hypoxia tolerance in plants remain poorly understood. Results In this study, we examined the effects of root hypoxia and exogenous ethylene treatments on leaf gas exchange, root hydraulic conductance, and the expression levels of several aquaporins of the plasma membrane intrinsic protein group (PIP) in trembling aspen (Populus tremuloides) seedlings. Ethylene enhanced net photosynthetic rates, transpiration rates, and root hydraulic conductance in hypoxic plants. Of the two subgroups of PIPs (PIP1 and PIP2), the protein abundance of PIP2s and the transcript abundance of PIP2;4 and PIP2;5 were higher in ethylene-treated trembling aspen roots compared with non-treated roots under hypoxia. The increases in the expression levels of these aquaporins could potentially facilitate root water transport. The enhanced root water transport by ethylene was likely responsible for the increase in leaf gas exchange of the hypoxic plants. Conclusions Exogenous ethylene enhanced root water transport and the expression levels of PIP2;4 and PIP2;5 in hypoxic roots of trembling aspen. The results suggest that ethylene facilitates the aquaporin-mediated water transport in plants exposed to root hypoxia.

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

Deformation Induced Percolating Porosity In High Pressure Torsioned (HPT) Copper

2011 ◽  
Vol 702-703 ◽  
pp. 105-108 ◽  
Author(s):  
Matthias Wegner ◽  
Jörn Leuthold ◽  
Sergiy V. Divinski ◽  
Daria Setman ◽  
Michael Zehetbauer ◽  
...  
Keyword(s):  
High Pressure ◽  
Impurity Concentration ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Processing Parameters ◽  
Tracer Method ◽  
Radiotracer Technique ◽  
Degree Of Deformation ◽  
Radio Tracer ◽  
Structural Aspects

Copper of different purity levels (4N, 5N) produced by High Pressure Torsion (HPT) with varying processing parameters is investigated utilizing the radiotracer technique. While the degree of deformation is constant, the effect of the applied quasi-hydrostatic pressure and of the impurity concentration on the as deformed samples is analysed. By applying the radio tracer method micro structural aspects are revealed that are not easily accessible by conventional methods. The measurements indicate the formation of a percolating porosity during the HPT process as a function of the applied pressure and (although less pronounced) of the impurity concentration.

Sign in / Sign up

Export Citation Format

Share Document