scholarly journals Changes in leaf water potential and photosynthesis of Bauhinia forficata Link under water deficit and after rehydration

Hoehnea ◽  
2013 ◽  
Vol 40 (1) ◽  
pp. 181-190 ◽  
Author(s):  
Rodrigo Fazani Esteves Sanches ◽  
Emerson Alves da Silva
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Strong Dependence ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Mean Values ◽  
Bauhinia Forficata ◽  
Response To Water

To evaluate the influence of different intensities of water deficit and rehydration on water relations and gas exchanges of Bauhinia forficata Link, plants were grown in a greenhouse for three months under the following water regimes: daily watered (control) and watered every 7 (7D) and 15 days (15D) returning to daily watering on 7D and 15D treatments at 75 days of the experiment. Aiming to evaluate short-term responses to re-hydration, plants of 7D and 15D treatments were re-watered 2 days before measurements and sampling was carried out at the 45th day of experiment. At fortnightly intervals (15, 30, 45, 60, 75, and 90 days) soil moisture (Usoil), leaf water potential (Ψwf), photosynthesis in response to photosynthetically active radiation (A × PPFD) to obtain the maximum net photosynthesis (Amax), and light saturation point (PARsat) were evaluated. The water deficit has affected water relations and photosynthesis with the lowest values observed in the treatments Usoil 7D, and 15D respectively, coinciding with the lowest Ψwf and Amax. Changes in PARsat in response to water deficit were observed showing mean values of 665, 275 and 254 µmol photons m-2 s-1 in control, 7D and 15D respectively. The return of daily watering after 75 days of experiment, promoted the recovery of Amax (7.8 and 9.6 µmol CO2 m-2 s-1) and PARsat (588 and 643 µmol photons m-2 s-1) in 7D and 15D respectively with values higher than control plants (4.7 µmol CO2 m-2 s-1 and 631 µmol photons m-2 s-1), suggesting a strong dependence of photosynthesis of Bauhinia forficata to the soil water availability.

scholarly journals COMPARATIVE DROUGHT RESISTANCE AMONG SIX BIRCH (BETULA) SPECIES

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1143f-1143
Author(s):  
Thomas G. Ranney ◽  
R.E. Bir ◽  
W.A. Skroch
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Leaf Gas Exchange ◽  
Leaf Water ◽  
Mild Stress ◽  
Turgor Loss Point ◽  
Leaf Osmotic Potential ◽  
Response To Water

In order to evaluate and compare adaptability to dry sites, plant water relations and leaf gas exchange were compared in response to water stress among six birch species: monarch birch (Betula maximowicziana), river birch (B. nigra), paper birch (B. papyrifera), European birch (B. pendula), `Whitespire' Japanese birch (B. platyphylla var. japonica `Whitespire'), and gray birch (B. pendula). After 28 days without irrigation, Japanese birch maintained significantly higher stomatal conductance (gs) and net photosynthesis (Pn) than did any of the other species, despite having one of the lowest mid-day water potentials. Evaluation of tissue water relations, using pressure-volume methodology, showed no evidence of osmotic adjustment for any of these species in response to water stress. However, there was substantial variation among species in the water potential at the turgor loss point; varying from a high of -1.34 MPa for river birch to a low of -1.78 MPa for Japanese birch. Rates of Pn and gs under mild stress (mean predawn leaf water potential of -0.61 MPa) were negatively correlated with leaf osmotic potential at full turgor and the leaf water potential at the turgor loss point.

Photosynthesis, transpiration, and leaf diffusive conductance of the cassava leaf in response to water stress

1983 ◽  
Vol 61 (1) ◽  
pp. 373-376 ◽  
Author(s):  
Jairo A. Palta
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Water Shortage ◽  
Leaf Water ◽  
Manihot Esculenta Crantz ◽  
Water Potential Measurements ◽  
Response To Water ◽  
Made In

The effects of short periods of water shortage on the CO2 and water vapour exchange of attached cassava (Manihot esculenta Crantz 'M Col 72') leaves were measured. Gas-exchange and leaf water potential measurements were made in outdoor grown plants previously subjected to varying periods without water. Leaf water potentials fell to between −0.61 and −1.06 MPa and net photosynthesis and transpiration rates declined as leaf water potential decreased. Estimations of the leaf internal CO2 conductance indicated that the linear relationship established between leaf water potential and net photosynthesis is dominated by, but not completely explained by, stomatal closure.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW

2011 ◽  
Vol 47 (1) ◽  
pp. 27-51 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
Water Potential ◽  
Water Use ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Water Productivity ◽  
Chloride Ions ◽  
Leaf Water ◽  
Flower Initiation ◽  
Plant Water ◽  
Drought Mitigation

SUMMARYThe results of research on the water relations and irrigation needs of coconut are collated and summarized in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information on the centres of origin and production of coconut and on crop development processes is followed by reviews of plant water relations, crop water use and water productivity, including drought mitigation. The majority of the recent research published in the international literature has been conducted in Brazil, Kerala (South India) and Sri Lanka, and by CIRAD (France) in association with local research organizations in a number of countries, including the Ivory Coast. The unique vegetative structure of the palm (stem and leaves) together with the long interval between flower initiation and the harvesting of the mature fruit (44 months) mean that causal links between environmental factors (especially water) are difficult to establish. The stomata play an important role in controlling water loss, whilst the leaf water potential is a sensitive indicator of plant water status. Both stomatal conductance and leaf water potential are negatively correlated with the saturation deficit of the air. Although roots extend to depths >2 m and laterally >3 m, the density of roots is greatest in the top 0–1.0 m soil, and laterally within 1.0–1.5 m of the trunk. In general, dwarf cultivars are more susceptible to drought than tall ones. Methods of screening for drought tolerance based on physiological traits have been proposed. The best estimates of the actual water use (ETc) of mature palms indicate representative rates of about 3 mm d−1. Reported values for the crop coefficient (Kc) are variable but suggest that 0.7 is a reasonable estimate. Although the sensitivity of coconut to drought is well recognized, there is a limited amount of reliable data on actual yield responses to irrigation although annual yield increases (50%) of 20–40 nuts palm−1 (4–12 kg copra, cultivar dependent) have been reported. These are only realized in the third and subsequent years after the introduction of irrigation applied at a rate equivalent to about 2 mm d−1 (or 100 l palm−1 d−1) at intervals of up to one week. Irrigation increases female flower production and reduces premature nut fall. Basin irrigation, micro-sprinklers and drip irrigation are all suitable methods of applying water. Recommended methods of drought mitigation include the burial of husks in trenches adjacent to the plant, mulching and the application of common salt (chloride ions). An international approach to addressing the need for more information on water productivity is recommended.

scholarly journals Optimizing irrigation and determining the most sensitive development stage to drought in barley (Hordeum vulgare L.) in a semi-arid environment

2020 ◽  
Vol 79 (1) ◽  
pp. 87-94
Author(s):  
Leila Romdhane ◽  
Nicola Dal Ferro ◽  
Amor Slama ◽  
Leila Radhouane
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Yield Components ◽  
Stem Elongation ◽  
Leaf Water ◽  
Water Deficit Stress ◽  
Growth Stages ◽  
Development Stages ◽  
Three Stages

Rising temperatures and increasing water scarcity, which are already important issues, are expected to intensify in the near future due to global warming. Optimizing irrigation in agriculture is a challenge. Understanding the response of crop development stages to water deficit stress provides an opportunity for optimizing irrigation. Here we studied the response of two barley varieties (Rihane, Martin), to water deficit stress at three development stages (tillering, stem elongation, and heading) by measuring water status and grain yield components in a field experiment in Tunisia. The three stages were selected due to their importance in crop growth and grain development. Water deficit stress was initiated by withholding water for 21 days at the three stages with subsequent re-watering. Water deficit led to a progressive decrease in leaf water potential. In both varieties, heading was the stage most sensitive to water deficit. Leaf water potential measurements indicated that water deficit stress was more severe during heading, which to some extent may have influenced the comparison between growth stages. During heading, the number of ears per plant and weight of a thousand grains were reduced by more than 70% and 50%, respectively compared with stress at tillering. Comparison of yield components showed differences between the two barley varieties only when the water deficit was produced during the tillering stage.

Genotypic variation in osmotic adjustment in grain sorghum. I. Development of variation in osmotic adjustment under water-limited conditions

1991 ◽  
Vol 42 (5) ◽  
pp. 747 ◽  
Author(s):  
T Tangpremsri ◽  
S Fukai ◽  
KS Fischer ◽  
RG Henzell
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Genotypic Variation ◽  
Genetic Material ◽  
Covariance Analysis ◽  
Leaf Water ◽  
The Other

Development of genotypic variation in osmotic adjustment was examined in two glasshouse experiments using two sets of sorghum material. In the first experiment, 47 S2 lines extracted from a randomly mated population were used, whereas in the other, inbred parents and their 15 hybrids were compared. In both experiments, water deficit was induced in two periods, one before anthesis and the other after anthesis for most genotypes. In both experiments osmotic potential at the beginning of the first drying period was similar among genotypes and therefore osmotic potential obtained under water deficit was used for the comparison of osmotic adjustment among genotypes. In the first drying period of both experiments, when stress was milder, about 40% of the variation in osmotic adjustment was accounted for by difference in leaf water potential. When the effect of water potential was removed by covariance analysis, there was significant genotypic variation in osmotic adjustment in the second experiment, but not in the first experiment. On the other hand, in the second drying period, when stress was more severe, the effect of leaf water potential on osmotic adjustment was small. There was significant genotypic variation in osmotic adjustment in both experiments after the water potential effect was removed by covariance analysis. Osmotic adjustment in the second drying period was also negatively correlated with grain sink/source ratio (number of grains/leaf area) in the first set of materials. The comparison of osmotic adjustment among hybrids and their parents showed that, in this particular set of genotypes, the female parents were more important than the male in determining osmotic adjustment of the hybrids. The genotypic variation was associated with performance under water deficit in the field. It is concluded that there is considerable genotypic variation in osmotic adjustment in the genetic material examined. Osmotic adjustment is, however, correlated with water potential and grain sink/source balance, and hence the selection for osmotic adjustment needs to ensure that high value is not due simply to low water potential or small head size.

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