The Effect of Plant Size on Wheat Response to Agents of Drought Stress. I. Root Drying

1997 ◽  
Vol 24 (1) ◽  
pp. 35 ◽  
Author(s):  
A. Blum ◽  
C. Y. Sullivan
Keyword(s):  
Drought Stress ◽  
Water Potential ◽  
Plant Height ◽  
Stress Condition ◽  
Stomatal Closure ◽  
Plant Size ◽  
Primary Response ◽  
Plant Performance ◽  
Shoot Biomass ◽  
Diffusive Resistance

Plant size has long been implicated in plant response to drought stress. This study is a first in a series of two intended to examine the effect of plant size on plant performance under the effect of various agents of drought stress. Variable plant size (in terms of plant height and shoot biomass) independent of genetic background effects was experimentally achieved using rht (tallest), Rht1 and Rht2 (medium) and Rht3 (shortest) homozygous height isogenic lines of spring wheat (Triticum aestivum cv. Bersee). Top-root drying is a common stress condition when the top soil dries in the field. In this experiment wheat was grown in hydroponics system in long PVC tubes. Stress was applied by allowing the top (40 cm) roots to dry throughout most of the growing season while the remaining roots were immersed in the nutrient solution. Average seasonal top-root water potential was reduced from –0.097 MPa in the controls to –1.93 MPa under stress. This stress condition caused a reduction in shoot biomass while it increased total root length. There was a general progressive increase in leaf diffusive resistance under the treatment as plants became larger. This stomatal closure could not be accounted for by reduction in leaf water potential. In fact, leaf turgor increased as stomatal diffusive resistance increased with increasing plant size, leading us to conclude that stomatal closure was the primary response to top-root drying, followed by turgor maintenance possibly as a result of a non-hydraulic signal produced by the drying top-roots. Smaller plants were affected relatively less than were larger plants by this stress condition in terms of stomatal closure, plant height, tillering and shoot biomass reduction. Grain yield per plant was actually increased by stress in the smallest plants while it was unaffected by stress in the larger plants. It is concluded that the smallest plants were the most resistant to top-root drying but absolute biomass and yield under this stress condition was the greatest in the largest plants because of their relatively greater potential.

The Effect of Plant Size on Wheat Response to Agents of Drought Stress. II. Water Deficit, Heat and ABA

1997 ◽  
Vol 24 (1) ◽  
pp. 43 ◽  
Author(s):  
A. Blum ◽  
C. Y. Sullivan ◽  
H. T. Nguyen
Keyword(s):  
Growth Rate ◽  
Heat Stress ◽  
Drought Stress ◽  
Osmotic Stress ◽  
Osmotic Adjustment ◽  
Plant Size ◽  
Shoot Biomass ◽  
Growth Reduction ◽  
Potential Growth ◽  
Juvenile Plants

Plant size has long been implicated in plant response to drought stress. This study is the second in a series of two intended to examine the effect of plant size on plant performance under the effect of various agents of drought stress. Variable plant size (in terms of plant height and shoot biomass) independent of genetic background effects was experimentally achieved using rht (tallest), Rht1 and Rht2 (medium) and Rht3 (shortest) homozygous height isogenic lines of spring wheat (Triticum aestivum) cultivars Bersee and April-Bearded. Plants were grown in hydroponic culture in the growth chamber. In the first experiment, juvenile plants were challenged by osmotic stress using polyethylene glycol (PEG) in the nutrient solution giving a water potential of –0.55 MPa. The control nutrient solution was at –0.05 MPa. Plant growth, shoot biomass, leaf area, relative water content (RWC) and osmotic adjustment (OA) were measured. In the second experiment, effects on growth rate of chronic heat stress and abscisic acid (ABA) in the root medium of juvenile plants were evaluated. Potential plant size as determined by shoot biomass in the controls at 25 days after emergence was greatest in rht, medium in Rht1 and Rht2, and smallest in Rht3 genotypes. Potential growth rate and leaf area were greater in plants of larger potential biomass (rht) than in plants of smaller potential biomass (Rht3). Growth reduction by osmotic stress was inversely related to plant size, while the extent of osmotic adjustment during osmotic stress was directly related to plant size. RWC did not vary with plant size. Relative growth reduction by heat stress and by ABA also decreased in smaller plants. ABA did not alleviate the depressing effect of heat on growth. Despite the greater stress tolerance of smaller (Rht3) plants, the absolute growth and biomass of large (rht) plants under stress conditions was always better than that of smaller plants. The results of these series of experiments suggest that greater stress tolerance of small plants is derived from their relatively smaller size and slower growth rate. Consequently, we conclude that growth under stress is sustained by potential growth rate and plant size of the genotype when stress is mild and by plant tolerance (even at the expense of potential growth rate and size) when stress is more severe.

COMPARISON BETWEEN TWO INBRED CORN LINES FOR DIFFUSIVE RESISTANCES, PHOTOSYNTHESIS AND TRANSPIRATION AS A FUNCTION OF LEAF WATER POTENTIAL

1974 ◽  
Vol 54 (4) ◽  
pp. 765-770 ◽  
Author(s):  
P. A. DUBÉ ◽  
K. R. STEVENSON ◽  
G. W. THURTELL
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Zea Mays L ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Potentials ◽  
Diffusive Resistance ◽  
Response To Water ◽  
Mesophyll Resistance

Relationships between (1) photosynthesis (2) transpiration (3) total diffusive resistance to water vapor and (4) mesophyll resistance and leaf water potential were examined in two lines of corn (Zea mays L.) differing in phenotypic response to water stress. One line (Q-188) was a wilting inbred and the other (DR-1) was an inbred known to have at least some heat and drought resistance under field conditions. No differences were found between inbred lines in net photosynthetic rate, transpiration rate and total diffusive resistance to water vapor at high or low leaf water potentials in the light. In both lines, stomatal closure began to occur between − 8.5 to − 9.5 bars. Similarly, rapid increases in both total resistance to water vapor diffusion and mesophyll resistance to carbon dioxide diffusion occurred within a narrow range of water potentials. However, leaf water potential, and thus all other parameters, differed markedly between lines when considered on a time scale. The early wilting of Q-188 suggested that high resistances to water flow were present in the xylem system.

The decoupling between gas exchange and water potential of Cinnamomum camphora seedlings during drought recovery and its relation to ABA accumulation in leaves

2020 ◽  
Vol 13 (6) ◽  
pp. 683-692
Author(s):  
Honglang Duan ◽  
Defu Wang ◽  
Xiaohua Wei ◽  
Guomin Huang ◽  
Houbao Fan ◽  
...  
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Stomatal Closure ◽  
Drought Severity ◽  
Physiology And Biochemistry ◽  
Drought Recovery ◽  
Moderate Drought ◽  
Rate Of Recovery

Abstract Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change, while the capacity of trees to cope with drought recovery through physiological and biochemical adjustment remains unclear. We aimed to examine the coupling of physiology and biochemistry in trees during drought and the following recovery. Methods Potted seedlings of Cinnamomum camphora were grown under well watered conditions prior to the experimental drought stress, which was initiated by withholding water. Seedlings were rewatered following attainment of two drought severities: mild drought (stomatal closure) and moderate drought (ψxylem = −1.5 MPa). We measured leaf-level water potential, gas exchange (photosynthesis and stomatal conductance), abscisic acid (ABA), proline and non-structural carbohydrates (NSCs) concentrations in seedlings of C. camphora during drought and a 4-day recovery. Important Findings We found that drought severity largely determined physiological and biochemical responses and affected the rate of recovery. Stomatal closure occurred at the mild drought stress, accompanied with ABA accumulation in leaves and decline in water potential, while leaf proline accumulation and variable NSC were evident at the moderate drought stress. More severe drought stress led to delayed recovery of gas exchange, but it did not have significant effect on water potential recovery. The relationships of water potential and gas exchange differed during drought stress and post-drought recovery. There was tight coupling between water potential and gas exchange during drought, but not during rewatering due to high ABA accumulation in leaves, thereby delaying recovery of stomatal conductance. Our results demonstrate that ABA could be an important factor in delaying the recovery of stomatal conductance following rewatering and after water potential recovery of C. camphora. Furthermore, greater drought severity had significant impacts on the rate of recovery of tree physiology and biochemistry.

scholarly journals Genetic Variability, Correlation and Path Analysis in Rice under Optimum and Stress Irrigation Regimes

2011 ◽  
Vol 3 (4) ◽  
pp. 134-142 ◽  
Author(s):  
Mina ABARSHAHR ◽  
Babak RABIEI ◽  
Habibollah Samizadeh LAHIGI
Keyword(s):  
Drought Stress ◽  
Plant Height ◽  
Stress Condition ◽  
Flag Leaf ◽  
Direct Effects ◽  
Irrigation Regime ◽  
Drought Stress Condition ◽  
Grain Width ◽  
Positive Direct ◽  
Paddy Yield

In order to estimate genetic variability and relationships among some agronomic traits of rice an experiment were conducted with 30 varieties of rice under two irrigation regimes. There were significant differences among the varieties for all traits. Broad-sense heritability varied from 0.05 for brown grain width to 0.99 for plant height and number of spikelet for panicle under optimum irrigation and from 0.1 for brown grain width to 0.99 for plant height. Evaluation of phenotypic and genotypic coefficient of variations (CV) showed that the lowest and highest phenotypic CV under optimum irrigation regime was observed to panicle fertility percentage and paddy yield and genotypic CV was related to brown grain width and plant height, respectively, while under drought stress condition, days to 50% flowering had the lowest phenotypic and genotypic CV and paddy yield and plant height had the highest phenotypic and genotypic CV. Furthermore, the lowest and highest expected genetic advance using selection intensity of 10% (i=1.75) were evaluated for brown grain width and plant height under optimum irrigation regime, respectively. Path analysis for paddy yield indicated that the number of spikelet per panicle and flag leaf length had positive direct effects and days to complete maturity and plant height had negative direct effects on paddy yield under optimum irrigation condition, while flag leaf width and number of filled grains per panicle had positive direct effects and days to 50% flowering had negative direct effect on paddy yield under drought stress condition.

scholarly journals Arabidopsis MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement

2020 ◽  
Vol 71 (19) ◽  
pp. 6092-6106 ◽  
Author(s):  
Ping-Xia Zhao ◽  
Zi-Qing Miao ◽  
Jing Zhang ◽  
Si-Yan Chen ◽  
Qian-Qian Liu ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Resistance ◽  
Molecular Mechanisms ◽  
Stomatal Density ◽  
Stomatal Closure ◽  
Negative Regulator ◽  
Stomatal Development ◽  
Mads Box ◽  
Mobility Shift ◽  
Aba Metabolism

Abstract Drought is one of the most important environmental factors limiting plant growth and productivity. The molecular mechanisms underlying plant drought resistance are complex and not yet fully understood. Here, we show that the Arabidopsis MADS-box transcription factor AGL16 acts as a negative regulator in drought resistance by regulating stomatal density and movement. Loss-of-AGL16 mutants were more resistant to drought stress and had higher relative water content, which was attributed to lower leaf stomatal density and more sensitive stomatal closure due to higher leaf ABA levels compared with the wild type. AGL16-overexpressing lines displayed the opposite phenotypes. AGL16 is preferentially expressed in guard cells and down-regulated in response to drought stress. The expression of CYP707A3 and AAO3 in ABA metabolism and SDD1 in stomatal development was altered in agl16 and overexpression lines, making them potential targets of AGL16. Using chromatin immunoprecipitation, transient transactivation, yeast one-hybrid, and electrophoretic mobility shift assays, we demonstrated that AGL16 was able to bind the CArG motifs in the promoters of the CYP707A3, AAO3, and SDD1 and regulate their transcription, leading to altered leaf stomatal density and ABA levels. Taking our findings together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

Plant height and height of the main ear in maize (Zea mays L.) at different locations and different plant densities

2002 ◽  
Vol 50 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Z. Gyenes-Hegyi ◽  
I. Pók ◽  
L. Kizmus ◽  
Keyword(s):  
Plant Height ◽  
Plant Density ◽  
Close Correlation ◽  
Plant Size ◽  
Considerable Effect ◽  
Maximum Height ◽  
The Best Approximation ◽  
Significant Difference ◽  
Plant Densities ◽  
Ear Height

The plant height and the height of the main ear were studied over two years in twelve single cross maize hybrids sown at three different plant densities (45, 65 and 85 thousand plants/ha) at five locations in Hungary (Keszthely, Gönc, Gyöngyös, Sopronhorpács, Martonvásár). The results revealed that plant height and the height of the main ear are important variety traits and are in close correlation with each other. It was found that the hybrids grew the tallest when the genetic distance between the parental components was greatest (Mv 4, Mv 5). The height of the main ear was also the greatest in these hybrids, and the degree of heterosis was highest (193% for plant height, 194% for the height of the main ear). The shortest hybrids were those developed between related lines (Mv 7, Mv 11). In this case the heterosis effect was the lowest for both plant height (128%) and the height of the main ear (144%). The ratio of the height of the main ear to the plant height was stable, showing little variation between the hybrids (37–44%). As maize is of tropical origin it grows best in a humid, warm, sunny climate. Among the locations tested, the Keszthely site gave the best approximation to these conditions, and it was here that the maize grew tallest. The dry, warm weather in Gyöngyös stunted the development of the plants, which were the shortest at this location. Plant density had an influence on the plant size. The plants were shortest when sown at a plant density of 45,000 plants/ha, and the main ears were situated the lowest in this case. At all the locations the plant and main ear height rose when the plant density was increased to 65,000 plants/ha. At two sites (Gönc and Sopronhorpács) the plants attained their maximum height at the greatest plant density (85,000 plants/ha). In Keszthely there was no significant difference between these two characters at plant densities of 65 and 85 thousand plants/ha, while in Gyöngyös and Martonvásár the greatest plant density led to a decrease in the plant and main ear height. The year had a considerable effect on the characters tested.

DIFFERENTIAL EFFECT OF SALINITY ON GROWTH, NUTRIENT CONCENTRATION AND CHLOROPHYLL IN SUGARCANE VARIETIES MEX 69-290 AND CP 72-2086

Agrociencia ◽  
2021 ◽  
Vol 55 (7) ◽  
pp. 597-610
Author(s):  
Odón Castañeda Castro ◽  
Miriam Cristina Pastelín Solano ◽  
Libia Iris Trejo Téllez ◽  
Eduardo Ariel Solano Pastelín ◽  
Fernando Carlos Gómez Merino
Keyword(s):  
Plant Height ◽  
Plant Performance ◽  
Saccharum Spp ◽  
Sugarcane Varieties ◽  
Randomized Design ◽  
Affected Plant ◽  
Nacl Concentration ◽  
Irrigation Solution ◽  
Completely Randomized Design ◽  
Better Than

Sugarcane (Saccharum spp. hybrids) is moderately sensitive to salinity and the effects on plant performance vary according to stress level and genotype. This study aimed to evaluate the effect of salt stress induced by application of different NaCl levels in the irrigation solution on plant height, indirect index of chlorophylls (SPAD), and macronutrients concentration (N, P, K, Ca, Mg and S) and Na in leaves of two sugarcane varieties: CP 72-2086 and Mex 69-290. The experiment was set in a completely randomized design with a 2×5 factorial arrangement. The study factors were sugarcane variety (CP 72-2086 and Mex 69-290) and NaCl concentration (0.0, 71.8, 143.6, 215.4 and  282.7 mM NaCl). Salinity as a single factor negatively affected plant height, SPAD units and N and P concentration in leaves; Ca concentrations increased, while K, Mg and S remained unaffected by the tested NaCl levels. Mex 69-290 grew higher and concentrated greater levels of N and K. Interactions of factors showed that salinity reduced growth in both varieties, but this reduction was more pronounced in CP 72-2086. SPAD units were also significantly reduced by salinity in both varieties. Concentrations of N and P in leaves decreased in both varieties in response to NaCl, while those of K and Ca increased in Mex 69-290. Concentration of Na was higher in Mex 69-290 which exhibited better performance than CP 72-2086. Sodium concentrations in leaves increased in direct relation to the tested NaCl concentrations. Mex 69-290 reached higher concentrations of Na in leave tissues but displayed better health than CP 72-2086. Thus, the variety Mex 69-290 showed more efficient Na-tolerance mechanisms related to Ca and K concentrations, and an indirect chlorophyll index better than CP 72-2086.

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