A comparison of the water relations characteristics of Helianthus annuus and Helianthus petiolaris when subjected to water deficits

Oecologia ◽  
1983 ◽  
Vol 58 (3) ◽  
pp. 309-313 ◽  
Author(s):  
M. A. Sobrado ◽  
Neil C. Turner
Keyword(s):  
Helianthus Annuus ◽  
Water Relations ◽  
Water Deficits ◽  
Helianthus Petiolaris

Water Relations in Cowpea and Pearl Millet Under Soil Water Deficits. I. Contrasting Leaf Water Relations

1992 ◽  
Vol 19 (6) ◽  
pp. 577 ◽  
Author(s):  
CL Petrie ◽  
AE Hall
Keyword(s):  
Soil Water ◽  
Pearl Millet ◽  
Water Relations ◽  
Pressure Chamber ◽  
Leaf Water ◽  
Surface Conductance ◽  
Pennisetum Americanum ◽  
Leaf Water Relations ◽  
Water Deficits ◽  
Rooting Media

Cowpea [Vigna unguiculata (L.) Walp.] can survive soil water deficits more effectively than pearl millet [Pennisetum americanum (L.) Leeke]. Cowpea and millet were grown in a glasshouse in different rooting media and different sizes of container, under wet and dry treatments, and as sole crops and intercrops to evaluate any differences in leaf water potential. Millet developed significantly lower predawn leaf water potentials (ΨL) than cowpea under the dry treatment of all of the rooting media and container sizes used, but both millet and cowpea maintained high predawn ΨL in the well-watered treatment. With the dry treatment, the same difference in predawn ΨL between cowpea and millet developed in plants grown either as sole crops or as intercrops in the same pot. These results suggest that plants grown as intercrops were somehow isolated from each other, even though their root systems may have overlapped, and that competition for water was probably not occurring. Differences in predawn ΨL between cowpea and millet were detected with either a pressure chamber or psychrometers, but values of ΨL varied with measurement method. Compared with psychrometer values, pressure chamber values became significantly lower in millet late in the dry treatment but were higher in cowpea. Agreement between the methods for measuring ΨL improved in cowpea when predawn xylem osmotic potential was added to the pressure chamber value. At the end of the experiments, leaf surface conductance to water vapour and leaf area were lower in millet than cowpea. Consequently, it is possible that the significantly lower predawn ΨL in millet was not due to greater water use by millet compared with cowpea.

The exclusion of ambient aerosols changes the water relations of sunflower (Helianthus annuus) and bean (Vicia faba) plants

2013 ◽  
Vol 88 ◽  
pp. 43-52 ◽  
Author(s):  
Shyam Pariyar ◽  
Thomas Eichert ◽  
Heiner E. Goldbach ◽  
Mauricio Hunsche ◽  
Jürgen Burkhardt
Keyword(s):  
Helianthus Annuus ◽  
Vicia Faba ◽  
Water Relations ◽  
Ambient Aerosols

scholarly journals Interaction of Huanglongbing and Foliar Applications of Copper on Water Relations of Citrus sinensis cv. Valencia

Plants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 298 ◽  
Author(s):  
Said A. Hamido ◽  
Robert C. Ebel ◽  
Kelly T. Morgan
Keyword(s):  
Surface Area ◽  
Water Relations ◽  
Citrus Sinensis ◽  
Fine Sand ◽  
Root Surface ◽  
Root Surface Area ◽  
Plant Water ◽  
Stem Water Potential ◽  
Water Deficits ◽  
The Impact

The following study was conducted to determine the impact of frequent foliar Cu applications on water relations of Huanglongbing (HLB)-affected Citrus sinensis cv. ‘Valencia’. HLB in Florida is putatively caused by Candidatus Liberibacter asiaticus that is vectored by the Asian citrus psyllid. The experiment was conducted in a psyllid-free greenhouse with trees grown in Immokalee fine sand soil with the trees well-maintained to promote health. Cu was applied to the foliage at 0×, 0.5×, 1×, and 2× the commercially recommended rates, which were 0, 46, 92, and 184 mM, respectively, with applications made 3× in both 2016 and 2017. Previous studies indicate that HLB causes roots to decline before the canopy develops symptoms, which increases the ratio between the evaporative surface area of the canopy to the uptake surface area of roots and increases the hydraulic strain within the tree. In the current study, overall growth was suppressed substantially by HLB and Cu treatments but the ratio between evaporative surface area (leaf surface area) and the uptake surface area of roots (feeder root surface area) was not affected by either treatment. Stem water potential (Ψxylem), which was used as a measure of plant water deficits and the hydraulic strain within the tree, was significantly 13% lower for HLB-affected trees than the non-HLB controls but were not affected by Cu treatments. All Ψxylem measurements were in a range typical of well-watered trees conditions. Stomatal conductance (ks) and root and soil resistances (Rr+s) were not affected by HLB and Cu. The results of this experiment suggest that tree leaf area and feeder roots are reduced when the trees are affected by HLB or are treated with foliar Cu applications such that plant water deficits are not significantly different over that of the controls.

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF AVOCADO (Persea americana Mill.): A REVIEW

2013 ◽  
Vol 49 (2) ◽  
pp. 256-278 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
South Africa ◽  
Water Stress ◽  
Water Use ◽  
Water Relations ◽  
Water Productivity ◽  
Chloride Ions ◽  
Persea Americana ◽  
Mature Trees ◽  
Water Deficits ◽  
Eastern Australia

SUMMARYThe results of research on the water relations and irrigation need of avocado are collated and reviewed in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information is given on the centre of origin (Mexico and Central America) and the three distinct ecological areas where avocados are grown commercially: (1) Cool, semi-arid climates with winter-dominant rainfall (e.g. Southern California, Chile, Israel); (2) Humid, subtropical climates with summer-dominant rainfall (e.g. eastern Australia, Mexico, South Africa); and (3) Tropical or semi-tropical climates also with summer-dominant rainfall (e.g. Brazil, Florida and Indonesia). Most of the research reported has been done in Australia, California, Israel and South Africa. There are three ecological races that are given varietal status within the species: Persea americana var. drymifolia (Mexican race), P. americana var. guatemalensis (Guatemalan race) and P. americana var. americana (Antillean, West Indian or Lowland race). Interracial crossing has taken place. This paper summarises the effects of water deficits on the development processes of the crop and then reviews plant–water relations, crop water requirements, water productivity and irrigation systems. Shoot growth in mature trees is synchronised into flushes. Flower initiation occurs in the autumn, with flowering in late winter and spring. Flowers form on the ends of the branches. A large heavily flowering tree may have over a million flowers, but only produce 200–300 fruits. Fruit load adjustment occurs by shedding during the first three to four weeks after fruit set and again in early summer. Water deficits during critical stages of fruit ontogeny have been linked to fruit disorders such as ring-neck. Reproductive growth is very resistant to water stress (compared with vegetative growth). Avocado is conventionally considered to be shallow rooted, although roots extend to depths greater than 1.5 m. The majority of feeder roots are found in the top 0.60 m of soil and root extension can continue throughout the year. Leaves develop a waxy cuticle on both surfaces, which is interrupted by stomata on the abaxial surface (350–510 mm−2), many of which are blocked by wax. Stomata are also present on the sepals and petals at low densities (and on young fruit). During flowering, the canopy surface area available for water loss is considerably increased. Stomatal closure is an early indicator of water stress, which together with associated changes in leaf anatomy, restricts CO2 diffusion. There have only been a few attempts to measure the actual water use of avocado trees. In Mediterranean-type climates, peak rates of water use (in summer) appear to be between 3 and 5 mm d−1. For mature trees, the crop coefficient (Kc) is usually within the range 0.4–0.6. The best estimate of water productivity is between 1 and 2 kg fruit m−3. Soil flooding and the resultant reduction in oxygen level can damage roots even in the absence of root rot. Avocado is particularly sensitive to salinity, notably that caused by chloride ions. Rootstocks vary in their sensitivity. Both drip and under-tree microsprinklers have been/are successfully used to irrigate avocado trees. Mulching of young trees is a recommended water conservation measure and has other benefits. A large proportion of the research reviewed has been published in the ‘grey’ literature as conference papers and annual reports. Sometimes, this is at the expense of reporting the science on which the recommendations are based in peer-reviewed papers. The pressures on irrigators to improve water productivity are considered.

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