scholarly journals Water Potential and Stomatal Resistance of Sunflower and Soybean Subjected to Water Stress during Various Growth Stages

1976 ◽  
Vol 58 (4) ◽  
pp. 537-540 ◽  
Author(s):  
Nasser Sionit ◽  
Paul J. Kramer
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Stomatal Resistance ◽  
Growth Stages

scholarly journals The effect of irrigation frequency on growth, flowering and stomatal conductance of osteospermum 'Denebola' and New Guinea impatiens 'Timor' grown on ebb·and-flow benches

2013 ◽  
Vol 54 (2) ◽  
pp. 59-68
Author(s):  
Jadwiga Treder ◽  
Joanna Nowak
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Growth Parameters ◽  
Soil Water Potential ◽  
New Guinea ◽  
Growth Stages ◽  
Irrigation Frequency ◽  
Growing Period ◽  
New Guinea Impatiens

The response of osteospermum 'Denebola' and New Guinea impatiens 'Timor' grown on ebb-and-flow benches to different water potential of growing medium applied during whole growing period was investigated by measuring plant growth parameters and stomatal conductance (g<sub>S</sub>). After cutting establishment, four different irrigation treatments based on soil water potential were applied to osteospermum: at -0,5 , -3,0 , -10,0 , -20 kPa. In the case of impatiens the last water treatment was omitted. Plants were evaluated when they reach one ofthe three growth stages: lateral shoots development, visible flower buds (osteospermum) or beginning of flowering (impatiens) and at flowering. All plants produced with a moderate water deficit (irrigation at -3 and -10 kPa) were more compact than plants irrigated at -0,5 kPa but their flowering were not affected. Strong decrease in pIant growth and flowering was observed when plants were irrigated at the lowest water potential (-20 kPa). However, for impatiens the highest irrigation frequency was also not favorable. As a result of water stress the decrease in stomatal conductance (g~) in both plants was observed. Osteospermum was more resistant to water stress than impatiens.

scholarly journals Anatomic and physiological modifications in seedlings of Coffea arabica cultivar Siriema under drought conditions

2014 ◽  
Vol 38 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Emanuelle Ferreira Melo ◽  
Christiane Noronha Fernandes-Brum ◽  
Fabrício José Pereira ◽  
Evaristo Mauro de Castro ◽  
Antonio Chalfun-Júnior
Keyword(s):  
Water Stress ◽  
Nitrate Reductase ◽  
Water Potential ◽  
Nitrate Reductase Activity ◽  
Stomatal Density ◽  
Reductase Activity ◽  
Stomatal Resistance ◽  
Partial Recovery ◽  
Worldwide Production ◽  
Weather Changes

Due to the weather changes prognostic for the coming years, the understanding of water deficit and physiological responses of plants to drought becomes an important requirement in order to develop technologies such as mechanisms to assist plants to cope with longer drought periods, which will be essential to maintenance of Brazilian and worldwide production. This study aimed to evaluate ecophysiological and anatomical aspects as well as the nitrate reductase activity in Siriema coffee seedlings subjected to four treatments: Daily irrigated, non-irrigated, re-irrigated 24 hours and re-irrigated 48 hours after different stress periods. Non-irrigation promoted a reduction in leaf water potential being accented from the ninth day of evaluation onwards. Re-irrigation promoted a partial recovery of the plant water potential. Non-irrigated plants showed an increase in stomatal resistance and reduction of transpiration and nitrate reductase activity. In the roots, there was a decrease in nitrate reductase activity under water stress. Leaf anatomical modifications were significant only for the adaxial surface epidermis and palisade parenchyma thickness, this latter characteristic being higher in control plants. Stomatal density and polar and equatorial diameter ratios showed the highest values in plants under water stress. In the roots, differences only in the cortex thickness being bigger in the non-irrigated treatment could be observed. Therefore, Siriema coffee plants under water stress show physiological, biochemical and anatomical modifications that contribute to the tolerance of this genotype to these conditions.

Recovery After Water Stress of Leaf Gas Exchange in Panicum maximum var. trichoglume

1980 ◽  
Vol 7 (3) ◽  
pp. 299 ◽  
Author(s):  
MM Ludlow ◽  
TT Ng ◽  
CW Ford
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Water Potential ◽  
Net Photosynthetic Rate ◽  
Net Photosynthesis ◽  
Recovery Phase ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Rate Of Recovery ◽  
The Relationship

Net photosynthesis of the last fully expanded leaf of P. maximum var. trichoglume was able to recover from leaf water potentials as low as -92 bar. The degree of stress experienced during the single drying cycle did not influence the maximum net photosynthetic rate attained during recovery, but the time taken to reach the maximum increased with the degree of stress experienced. During the first 24 h, the rate of recovery of net photosynthesis was mainly determined by the rate at which the water status improved. Leaves which experienced water potentials less than c. -40 bar had a slower rate of recovery of water potential than less stressed leaves. This was partially offset by higher rates of net photosynthesis. Furthermore, the relationship between leaf water potential and net photosynthesis recorded during the drying cycle was different from those measured during recovery. Thus different relationships must be used in models simulating behaviour during water stress and subsequent recovery. Stomatal resistance exerted greater control than intracellular resistance over net photosynthesis in the recovery phase, irrespective of the water potential before rewatering or whether plants were preconditioned to stress. Although abscisic acid concentration was positively related to leaf water potential and stomatal resistance during the drying cycle, the relationship between abscisic acid concentration and stomatal resistance during recovery was poor or absent. Sucrose and amino-acid nitrogen accumulated during stress and decreased during recovery. However, the level of non- structural carbohydrates or nitrogen compounds in the recovery phase did not appear to influence net photosynthetic rate or its components. In fact, the reverse appeared to occur: the rate of photosynthesis and growth seemed to determine the levels of these compounds.

COMPARATIVE WATER STRESS STUDIES ON DROUGHT RESISTANT AND SUSCEPTIBLE CORN GROWN IN CHAMBER AND FIELD ENVIRONMENTS

1983 ◽  
Vol 63 (4) ◽  
pp. 775-787 ◽  
Author(s):  
A. L. SKRETKOWICZ ◽  
G. W. THURTELL
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Extended Period ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Stress Studies ◽  
Controlled Environments ◽  
Drought Resistant ◽  
Corn Plants

Drought resistant and drought susceptible corn plants were grown in both field and growth room environments in order to study differences in response to water stress attributable to their growth environments, including their prestress history.After 40–56 days of growth, field- and chamber-grown drought resistant and susceptible plants were placed in a growth cabinet for the drought stress experiments. There they underwent two stress cycles, during which time water was witheld. During the cycles, leaf water potential, transpiration, stomatal resistance and soil moisture content were monitored. The response differences due to water stress between the drought resistant and susceptible plants were first examined. Response differences due to their prestress growth environments were then considered.The responses of the field- and chamber-grown drought resistant plants to stress were found to be similar although there were differences in the absolute value of the responses measured. This was also true of the drought susceptible plants. The drought resistant plants were able to maintain their ability to extract water for a longer period of time than the susceptible plants. They maintained low stomatal resistance values for a large part of the drying cycle. The values of leaf water potential at which the stomatal resistances increased were lower than those of the drought susceptible plants. This enabled the drought resistant plants to extend their period of water utilization.During the drying cycles, the field-grown drought resistant and susceptible plants maintained low stomatal resistances and high transpiration rates for a longer period of time than their chamber counterparts. The values of leaf water potential at which stomatal resistance increased and transpiration decreased were lower than those of the chamber-grown plants, allowing the field-grown plants a slightly extended period of water utilization.The knowledge of prestress history of plants grown in different environments is shown to be of importance when comparative studies between field and controlled environments are undertaken. The similarity in response found between field- and chamber- grown plants is a useful factor as the chamber work with these particular cultivars is shown to be representative of field response at this location.Key words: Water stress, drought resistance, Zea mays L.

scholarly journals Tolerance to Drought and Water Stress Resistance Mechanism of Castor Bean

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1580
Author(s):  
Eleni G. Papazoglou ◽  
Efthymia Alexopoulou ◽  
George K. Papadopoulos ◽  
Garifalia Economou-Antonaka
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Stress Resistance ◽  
Water Scarcity ◽  
Castor Bean ◽  
Resistance Mechanism ◽  
Stomatal Resistance ◽  
Leaf Water ◽  
Leaf Number

Castor bean (Ricinus communis L.) is a multipurpose crop; its oil has numerous applications worldwide and the last decade demonstrated a growing international demand. The aim of this work was to investigate the level of castor bean tolerance to drought and its possession of a water stress resistance mechanism by applying three different water regimes in a glasshouse pot experiment conducted for two years. The treatments applied were 70% (T70-control), 55% (T55) and 40% (T40) of the available soil moisture. The results showed that the growth parameters height, trunk diameter, and fresh and dry weights of leaves and stems were not affected by the moderate water scarcity (T55), while they were significantly decreased by T40. Significant decrease in leaf number was observed in both T55 (17%) and T40 (27%) plants, with a delay of 4 weeks in the lower treated plants. Leaf area was decreased by 54% and 20% in T55 and T40 respectively, indicating that its reduction was mainly due to a reduction of leaf size than of leaf number. The leaf water potential was increased negatively with increasing stress, showing a water loss and decrease of turgidity in cells. Stomatal resistance was significantly higher at the higher water scarcity and this response indicates a water stress resistance mechanism. This result was also confirmed by the regression analysis performed between stomatal resistance and leaf water potential. In conclusion, castor bean showed a tolerance ability under water stress conditions and its early physiological reaction allows its acclimatization to drought conditions.

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