scholarly journals Macadamia responses to mild water stress at different phenological stages

2003 ◽  
Vol 54 (1) ◽  
pp. 67 ◽  
Author(s):  
R. A. Stephenson ◽  
E. C. Gallagher ◽  
V. J. Doogan
Keyword(s):  
Water Stress ◽  
High Stress ◽  
Management Tool ◽  
Mild Stress ◽  
Floral Initiation ◽  
Xylem Water Potential ◽  
Phenological Stages ◽  
Oil Accumulation ◽  
Yield And Quality ◽  
Mild Water Stress

Mild water stress was imposed on bearing macadamia trees in through-draining lysimeters at various phenological stages. Water was withheld until a xylem water potential (Ψx) of –1.5 to 2.0 MPa was reached, this being maintained by partial water replenishment at 2-day intervals. Flowering, nut set, nut development, yield, and quality responses were assessed to identify critical, stress-sensitive stages. Stress during nut maturation was particularly detrimental to both yield and quality, although stress during floral development and the premature nut drop also had adverse effects. Low yields were due to reduced nut number and smaller nuts. Lower photosynthesis (c. 2 μmol CO2/m2.s) at –1.5 MPa would account for reduced yield and poorer quality during nut maturation when energy demands of active oil accumulation are high. Stress at floral initiation was generally not detrimental.Overall, stress restricted growth. The rate of girth growth was significantly lower when stress was applied during the dormant floral initiation stage. When stress coincided with normal periods of vegetative growth, flushing was delayed until after re-watering when greater foliage production was stimulated. Judiciously imposing mild stress may be used to manipulate macadamia phenology, although it may not necessarily conserve water. Further refinement would be needed to develop stress manipulation as a practical and reliable management tool to achieve higher yields. Water should be applied to alleviate stress during critical stages of nut development and maturation. Mild stress after the current crop is mature, however, is unlikely to be detrimental to macadamia yield or quality. It may, in fact, be beneficial through manipulation of flushing patterns that influence yield.

Water stress and phenology in wheat

1977 ◽  
Vol 28 (2) ◽  
pp. 177 ◽  
Author(s):  
JF Angus ◽  
MW Moncur
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Mild Stress ◽  
Floral Initiation ◽  
Severe Stress ◽  
Development Models ◽  
Crop Development

Single wheat plants (cv. Gabo) were sown in tall pots and top-watered so that growth proceeded without stress until the time of floral initiation. Having reached this stage, plants encountered increasing stress as soil water was depleted. At intervals after the dawn leaf water potential, ψ1, had reached values of –5, –10, –15 bars etc., the stress was relieved with water sufficient for unstressed development until anthesis. The anthesis dates of plants which had encountered mild stress (ψ1 down to about ndash;15 bars) were ahead of the well-watered control, while those which had encountered more severe stress (ψ1 from about ndash;25 to ndash;40 bars) flowered after the controls. The results are discussed in relation to the possibilities of including the effects of stress in crop development models.

scholarly journals Fine Root Hydraulic Conductance Is Related to Post-transplant Recovery of Two Quercus Tree Species

2014 ◽  
Vol 139 (6) ◽  
pp. 649-656 ◽  
Author(s):  
Jingjing Yin ◽  
Nina L. Bassuk ◽  
Madeline W. Olberg ◽  
Taryn L. Bauerle
Keyword(s):  
Water Stress ◽  
Fine Roots ◽  
Fine Root ◽  
Hydraulic Conductance ◽  
Root Pruning ◽  
Root Hydraulic Conductance ◽  
Xylem Water Potential ◽  
Post Transplant ◽  
Transplant Shock ◽  
Mild Water Stress

In our study, we investigated whether root hydraulic conductance is related to post-transplant recovery. We used two Quercus species that differ in their transplant ability, Q. bicolor and Q. macrocarpa. Q. bicolor easily survives transplanting, whereas Q. macrocarpa often does not. We compared root hydraulic conductance after transplanting between control (without root pruning) and root-pruned, 1-year-old, small-caliper trees. We also examined the effects of transplant timing on post-transplant recovery of large-caliper trees. Hydraulic conductance in fine roots was correlated with recovery of the two Quercus species after transplanting. Six months after transplanting, small-caliper Q. bicolor trees had similar specific hydraulic conductance (KS) in fine roots compared with the KS before root-pruning, whereas fine root KS in small-caliper Q. macrocarpa trees decreased. Lower pre-dawn and midday xylem water potential in root-pruned Q. macrocarpa 6 weeks after transplanting indicates that root-pruned Q. macrocarpa experienced transplanting-induced water stress. For large-caliper trees, all Q. macrocarpa trees exhibited typical symptoms of transplant shock regardless of transplant timing, which was the result of higher vulnerability to mild water stress compared with Q. bicolor, resulting in a large reduction in fine root KS. Fine root KS in spring-transplanted Q. bicolor trees was much higher than that in fall-transplanted trees, implying spring transplanting is optimal for Q. bicolor. Other intrinsic characteristics of the species should be considered in the future when making better decisions on transplant timing such as xylem anatomy, carbon storage, rhizosphere conditions, and plant growth.

scholarly journals Effect of Early Water Deficits on Nodulation and Nitrogen Content of Inoculated Soybean

2018 ◽  
Vol 20 (2) ◽  
pp. 11-16
Author(s):  
JA Adjetey ◽  
BNG Nxumalo
Keyword(s):  
Water Stress ◽  
Dry Mass ◽  
Growth Stages ◽  
Mild Stress ◽  
Severe Stress ◽  
Production Potential ◽  
Severe Water Stress ◽  
Kwazulu Natal ◽  
The University ◽  
Mild Water Stress

The study was conducted at the University of KwaZulu-Natal (29o37’ S, 30o23’ E) from May to November 2012 under controlled environment conditions with three water regimes namely: well watered controls, mild water stress to -1.4 MPa and severe water stress to -2.0 MPa, at the V4 (28 DAS) and V5 stages (35 DAS). Severe stress significantly reduced no. of nodule and root mass, leaf area, shoot dry mass and uptake, regardless of the stage. Mild stress on the other hand had little effect on this parameter as plants recovered on re-watering, to attain values similar to the control treatments. The V4 and V5 stages can recover from mild stress, but severe stress at both growth stages reduces nodulation and nitrogen uptake and this can lead to reduction in production potential of soybean.Bangladesh Agron. J. 2017, 20(2): 11-16

scholarly journals Detecting Mild Water Stress in Olive with Multiple Plant-Based Continuous Sensors

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 131
Author(s):  
Giulia Marino ◽  
Alessio Scalisi ◽  
Paula Guzmán-Delgado ◽  
Tiziano Caruso ◽  
Francesco Paolo Marra ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Stomatal Closure ◽  
Irrigation Management ◽  
Great Influence ◽  
Solid Base ◽  
Mild Stress ◽  
Tissue Elasticity ◽  
Stress Studies ◽  
Mild Water Stress

A comprehensive characterization of water stress is needed for the development of automated irrigation protocols aiming to increase olive orchard environmental and economical sustainability. The main aim of this study is to determine whether a combination of continuous leaf turgor, fruit growth, and sap flow responses improves the detection of mild water stress in two olive cultivars characterized by different responses to water stress. The sensitivity of the tested indicators to mild stress depended on the main mechanisms that each cultivar uses to cope with water deficit. One cultivar showed pronounced day to day changes in leaf turgor and fruit relative growth rate in response to water withholding. The other cultivar reduced daily sap flows and showed a pronounced tendency to reach very low values of leaf turgor. Based on these responses, the sensitivity of the selected indicators is discussed in relation to drought response mechanisms, such as stomatal closure, osmotic adjustment, and tissue elasticity. The analysis of the daily dynamics of the monitored parameters highlights the limitation of using non-continuous measurements in drought stress studies, suggesting that the time of the day when data is collected has a great influence on the results and consequent interpretations, particularly when different genotypes are compared. Overall, the results highlight the need to tailor plant-based water management protocols on genotype-specific physiological responses to water deficit and encourage the use of combinations of plant-based continuously monitoring sensors to establish a solid base for irrigation management.

Grafting under water stress in tomato cherry: improving the fruit yield and quality

2012 ◽  
Vol 161 (3) ◽  
pp. 302-312 ◽  
Author(s):  
E. Sánchez-Rodríguez ◽  
R. Leyva ◽  
C. Constán-Aguilar ◽  
L. Romero ◽  
J.M. Ruiz
Keyword(s):  
Water Stress ◽  
Fruit Yield ◽  
Yield And Quality

scholarly journals Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress

2014 ◽  
Vol 44 (1) ◽  
pp. 67-77 ◽  
Author(s):  
Gracilene Fernandes da Costa Azevedo
Keyword(s):  
Water Stress ◽  
Higher Plants ◽  
Field Capacity ◽  
Outdoor Exposure ◽  
Photosynthetic Parameters ◽  
Bertholletia Excelsa ◽  
Full Sunlight ◽  
Carapa Guianensis ◽  
Light Levels ◽  
Mild Water Stress

Light and water are important factors that may limit the growth and development of higher plants. The aim of this study was to evaluate photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress. I used six independent pre-acclimation treatments (0, 90 (11h15-12h45), 180 (10h30-13h30), 360 (09h00-15h00), 540 (07h30-16h30) and 720 min (06h00-18h00)) varying the time of exposure to full sunlight (PFS) during 30 days, followed by whole-day outdoor exposure for 120 days. Before PFS, the plants were kept in a greenhouse at low light levels (0.8 mol m-2 day-1). The PFS of 0 min corresponded to plants constantly kept under greenhouse conditions. From the beginning to the end of the experiment, each PFS treatment was submitted to two water regimes: moderate water stress (MWS, pre-dawn leaf water potential (ΨL) of -500 to -700 kPa) and without water stress (WWS, ΨL of -300 kPa, soil kept at field capacity). Plants under MWS received only a fraction of the amount of water applied to the well-watered ones. At the end of the 120-day-period under outdoor conditions, I evaluated light saturated photosynthesis (Amax), stomatal conductance (g s), transpiration (E) and plant growth. Both Amax and g s were higher for all plants under the PFS treatment. Stem diameter growth rate and Amax were higher for C. guianensis subjected to MWS than in well-watered plants. The contrary was true for B. excelsa. The growth of seedlings was enhanced by exposure to full sunlight for 180 minutes in both species. However, plants of B. excelsa were sensitive to moderate water stress. The higher photosynthetic rates and faster growth of C. guianensis under full sun and moderate water stress make this species a promissory candidate to be tested in reforestation programs.

scholarly journals Under-vine cover crops: impact on weed development, yield and grape composition

OENO One ◽  
2020 ◽  
Vol 54 (4) ◽  
pp. 975-983
Author(s):  
Javier Abad ◽  
Marín Diana ◽  
Santesteban L. Gonzaga ◽  
Cibriáin José Félix ◽  
Sagüés Ana
Keyword(s):  
Water Stress ◽  
Cover Crops ◽  
Drip Irrigation ◽  
Vegetative Growth ◽  
Cover Crop ◽  
Sustainable Management ◽  
Arid Regions ◽  
Management Tool ◽  
Second Year ◽  
Semi Arid

This study aims to evaluate the interest of using an under-vine cover crop as a sustainable management tool replacing herbicides or tillage to control weeds, evaluating its effects on yield and berry parameters in a semi-arid climate. The performance of Trifolium fragiferum as an under-vine cover crop was evaluated in 2018 and 2019 in a Merlot vineyard in Traibuenas (Navarra, Spain). This trial showed that the soil under the vines was covered by 80 % of the cover crop in August 2018 and 100 % in Aug 2019, with clover (T. fragiferum) comprising around 26 % and 70 % of the cover crop surface, respectively. The presence of the cover crop only reduced the number of shoots in the second year, although both years there was an increment in water stress. Neither yield, cluster weight nor berry weight were affected by the presence of the under-vine cover crop. Similarly, no changes in grape composition were observed. The use of T. fragiferum-like cover crops under the vine allows for better control of weeds, provided a good installation is achieved. In the first two years, this cover crop reduced vegetative growth and increased water deficit slightly. However, no changes in yield and grape composition were observed.In a context of herbicide suppression and search for sustainable management, under-vine clover cover crops constitute a viable alternative in semi-arid regions provided drip irrigation can be applied. 

scholarly journals Mist Irrigation Reduces Post-transplant Desiccation of Bare-root Trees

1994 ◽  
Vol 12 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Rick M. Bates ◽  
Alex X. Niemiera
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Acer Platanoides ◽  
Sensitive Species ◽  
Xylem Water Potential ◽  
Post Transplant ◽  
Norway Maple ◽  
Relative Water ◽  
Bare Root ◽  
Cherry Trees

Abstract Desiccation during storage and reestablishment is a major factor contributing to poor regrowth of transplanted bare-root trees. The effect of overhead mist irrigation on reducing post transplant water stress in Norway maple (Acer platanoides L. ‘Emerald Lustre’) and Yoshino cherry (Prunus x yedoensis) was examined. Bare-root Norway maple (desiccation tolerant) and Yoshino cherry (desiccation sensitive) trees were transplanted into pine bark-filled containers and subjected to mist or non-mist treatments. Stem xylem water potential, relative water content, and survivability were determined. Xylem water potential increased (became less negative) for misted maple and cherry trees. Water potential increased for non-misted maple and decreased for non-misted cherry trees. Twenty-seven percent of non-misted cherries were evaluated as nonmarketable due to stem dieback compared to 0% for misted trees. Results of this study indicate that mist irrigation effectively reduces desiccation damage for desiccation sensitive species such as cherries and hawthorns.

Implementation of K-Modes Algorithm for Clustering of Stress Causes in University Students

2021 ◽  
Vol 9 (3) ◽  
pp. 419
Author(s):  
Ni Putu Mira Novita Dewi ◽  
Ida Bagus Gede Dwidasmara
Keyword(s):  
Stress Level ◽  
Clustering Algorithm ◽  
High Stress ◽  
Optimal Number ◽  
Mild Stress ◽  
Student Groups ◽  
High Stress Level ◽  
Internal And External Factors ◽  
Python Programming ◽  
Cluster 2

Stress is an inevitable part of life in a college environment. The variety of factors that cause stress in students, it is necessary to cluster the factors that cause stress in students to see the description of the characteristics of each cluster of students. The clustering process is carried out to identify the causes of stress in student groups and their relationship to these internal and external factors. Cluster analysis can be used as a reference to decide on efforts to handle and prevent increased stress in students. The clustering process is carried out using the Python programming language. The algorithm used is the k-modes clustering algorithm. This algorithm is suitable for clustering categorical data. The optimal number of clusters obtained from the implementation of the elbow method is three clusters. Cluster 1 is a cluster with a mild stress level, the main cause of stress is academic issues. Cluster 1 is the only group where the majority of the cause of stress is not financial. Cluster 2 is a cluster with a high stress level which causes various stressors. However, cluster 2 is the only cluster where the cause of stress is on careers and on involvement in hostels, clubs, and society. Cluster 3 is a cluster with a medium stress level. This cluster is the only cluster dominated by male gender. The main cause of stress in this cluster is academic and financial.

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