Verticillium wilt of chrysanthemum: quantitative relationship between increased stomatal resistance and local vascular dysfunction preceding wilt

1976 ◽  
Vol 54 (10) ◽  
pp. 1023-1034 ◽  
Author(s):  
William E. MacHardy ◽  
Lloyd V. Busch ◽  
Robert Hall

The relationship between the development of water stress and foliar symptom expression within chrysanthemum (Chrysanthemum morifolium Ramat) cuttings infected with Verticillium dahliae Kleb. was examined using relative water content (RWC), diffusive resistance to water vapor loss (stomatal resistance), and dye distribution along water-transport pathways as indicators of water stress. The RWC remained at a normal level until symptoms appeared, but stomatal resistance increased beginning about 8 days before symptoms. Dye movement along xylem elements was uniform within uninoculated checks and also within infected plants until stomatal resistances increased. Veinal dye distribution was incomplete within tissue exhibiting increased stomatal resistances, and the extent of dye interruption was closely aligned to the magnitude of resistance increase. Apparently, stomatal closure effectively prevented tissue desiccation under conditions of high, localized internal water stress, but this mechanism could not prevent tissue from becoming flaccid or wilted when water transport became so limited that water was deficient even within the large veins.

2011 ◽  
Vol 68 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Sidnei Deuner ◽  
José Donizeti Alves ◽  
Ilisandra Zanandrea ◽  
Patrícia de Fátima Pereira Goulart ◽  
Neidiquele Maria Silveira ◽  
...  

Coffee (Coffea arabica) plants show a positive relationship between stomatal closure and formation and accumulation of H2O2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψw) were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψw during the evaluated period for plants in field capacity. However, an expressive decrease of Ψw following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψw decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψw in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.


2005 ◽  
Vol 56 (10) ◽  
pp. 1069 ◽  
Author(s):  
Shahram Mohammady-D ◽  
Keith Moore ◽  
John Ollerenshaw ◽  
Behrooz Shiran

Monosomic plants from an Australian variety (Oxley) having low stomatal resistance (SR), low leaf relative water content (LRWC), and high carbon isotope discrimination (Δ) were crossed with variety Falchetto having opposite characters in order to produce F2 backcross reciprocal monosomic families. The families were assessed under pre-anthesis water-stress conditions in a controlled growth chamber. F2 backcross reciprocal monosomic analysis suggested possible allelic variations between chromosomes 1A, 3A, 6A, 7A, 7B, 1D, and 4D of Falchetto and their homologues in Oxley for LRWC. This analysis also suggested possible allelic variation between chromosomes 5A, 1A, and 3A of Falchetto and their homologues in Oxley for SR. Extending the analysis to the F3 disomic generation and the assessment of LRWC at this generation confirmed that reciprocals for chromosomes 3A and 6A showed significant differences. F2 backcross reciprocal monosomic analysis for Δ suggested allelic variations on chromosomes 1D, 4D, and 5D. However, chromosome 1D from Falchetto had the highest difference from its homologue in Oxley. Assessing the reciprocals of this chromosome for vegetative evapotranspiration efficiency (ETEveg) at the F3 disomic generation indicated that the observed variation for Δ was translated into differences for ETEveg. These results indicate that chromosome 1D of Falchetto is promising in reducing Δ and that the improvement of wheat varieties for ETEveg can be done by selection for Δ. Finally, plieotropic effects of some chromosomes were observed for the characters under study. This suggests the existence of genetic factors on these chromosomes affecting more than one character. However, some pleiotropic effects could also be due to non-genetic developmental interactions.


2019 ◽  
Vol 225 (1) ◽  
pp. 126-134 ◽  
Author(s):  
Celia M. Rodriguez‐Dominguez ◽  
Timothy J. Brodribb

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1125a-1125
Author(s):  
Rida Shibli ◽  
L. Art Spomer ◽  
Mary Ann Lila Smith

Osmotic adjustment in response to decreasing media water availability was observed for in vitro Chrysanthemum morifolium Ramat. cultivars Bright Golden Anne, Deep Luv, and Lucido. Water stress was induced by increasing sorbitol (0, 0.1, 0.2, 0.3, 0.4 M), mannitol (0, 0.1, 0.2, 0.3, 0.4 M), and sucrose (30, 45, 60, 75, 90 g·l-1) concentrations in modified MS media (2 mg·l-1 BA and 0.1 mg·l-1 NAA). Osmotic adjustment was evidenced by a significant reduction in measured cell sap osmotic potential (R2 = 0.78, 0.96, 0.91 for sucrose, sorbitol, and mannitol respectively) in all cultivars. Shoot length, weighted density (apparent mass), and proliferation were significantly reduced by sorbitol and mannitol treatments. Sucrose reduced shoot proliferation, increased length, and had an inconsistent effect on weighted density. Cultures grown on media without hormones showed tremendous increase in root number up to 60 g·l-1 sucrose. Sorbitol had a negligible effect on rooting at 0.1 M but no roots developed at higher sorbitol concentrations or in any mannitol treatments. Plants transferred to a non-water-stress media after they had experienced in vitro water stress exhibited no change in osmotic properties from the stress treatments.


1978 ◽  
Vol 5 (2) ◽  
pp. 113 ◽  
Author(s):  
GG Johns

A series of physiological parameters was monitored under glasshouse conditions on micro-swards of four temperate herbage species. The micro-swards were grown on large soil cores so that the slow onset of water stress usually encountered in the field was simulated when water was withheld. Generally, water use per unit cover continued at a high rate even when water stress was causing considerable leaf death. Leaf diffusive conductance fell only gradually and did not reach minimum values until after much of herbage on the swards was dead. Stomatal closure in all species reduced water use per unit foliage cover by only 20-30%. Under increasing water stress, gross photosynthesis resembled stomatal conductances in remaining substantial (>50% of controls) even when relative water contents had fallen to below 80%. Both water use and gross photosynthesis were reduced more as a result of the reduced leaf area available for gaseous exchange than by the influence of stomatal action. Leaf moisture retention curves were similar for all species, there being a loss of c. 10% of relative water content per unit leaf water potential, down to drier than -5 MPa. It was concluded that the generally inferior herbage yields of white clover under dryland field conditions could be due in part to its relatively high leaf diffusive conductances when under water stress, while the better than average tall fescue yields under similar conditions may be attributed in part to its ability to roll its leaves tightly when water stress prevails.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 491a-491
Author(s):  
James T. Cole ◽  
Janet C. Cole

An experiment was conducted to evaluate the performance of five ornamental grass species under reduced moisture. This experiment was conducted in the greenhouse with three water treatments for each species: 1) Well-watered plants were irrigated daily throughout the experiment, 2) acclimated-plants were exposed to four drought cycles prior to a final drought period in which measurements were taken, and 3) non-acclimated plants received daily irrigation until undergoing a drought cycle in which measurements were taken. A drought cycle was defined as the time from irrigation until Time Domain Reflectometry (TDR) measured 0 (zero). Preliminary observations determined the plants to be under severe stress, but capable of recovering at TDR measurements of 0. All plants were established from tillers of a single parent for each species. Two plants of each species for the three treatments were established in five blocks. Leaf water potential, osmotic potential, transpiration, stomatal resistance, and relative water content were measured during the drought cycle. At the end of the experiment the leaf area and root and shoot dry weights were determined, root to shoot ratio and leaf area ratio were calculated, and the plants were analyzed for macronutrient and micronutrient contents.


1975 ◽  
Vol 53 (24) ◽  
pp. 3041-3050 ◽  
Author(s):  
C. H. A. Little

In experiments with attached and detached shoots of balsam fir, Abies balsamea L., synthetic (±)abscisic acid (ABA) (1) reduced photosynthesis and transpiration by inducing stomatal closure, (2) inhibited indoleacetic acid (IAA) - induced cambial activity in photosynthesizing and non-photosynthesizing shoots, and (3) inhibited the basipetal movement of [14C]IAA. Neither gibberellic acid nor kinetin counteracted the inhibitory effect of (±)ABA on IAA-induced cambial activity. In addition it was demonstrated that increasing the internal water stress increased the level of endogenous ABA in the phloem–cambial region of bark peelings and decreased the basipetal movement of [14C]IAA through branch sections. On the basis of these findings it is proposed that internal water stress inhibits cambial activity, partly through increasing the level of ABA; the ABA acts to decrease the provision of carbohydrates and auxin that are required for cambial growth.


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