scholarly journals Effects of 5-chloro-3-methyl-4-nitro-1H-pyrazole and Ethephon on Citrus Leaf Function and Water Relations

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1008A-1008
Author(s):  
Kuo-Tan Li ◽  
Jackie Burns ◽  
Luis Pozo ◽  
Jim Syvertsen
Keyword(s):  
Photosystem Ii ◽  
Water Relations ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Fruit Peel ◽  
Photosystem Ii Efficiency ◽  
Citrus Leaf ◽  
Content Ratio ◽  
High Concentrations ◽  
Leaf Chlorophyll Fluorescence

To determine the effects of abscission compounds 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP) and ethephon on citrus leaf function and water relations, we applied CMNP at 0, 200, 500, 1000, or 2000 ppm, or ethephon at 400 or 800 ppm, to canopies of fruiting potted and field citrus trees during the harvest season. Both compounds induced fruit and leaf drop after 3 days of application, especially at high concentrations. Low concentrations of CMNP (0, 200, or 500 ppm) or either ethephon treatments did not affect leaf photosystem II efficiency, as indicated by leaf chlorophyll fluorescence (Fv/Fm). High concentrations of CMNP (1000 or 2000 ppm) immediately reduced photosystem II efficiency in leaves and fruit peel. However, Fv/Fm of leaves remaining on the trees was gradually restored and close to the level of control after 4 days of treatment. Both compounds had little effect on chlorophyll content, ratio of chlorophyll a to chlorophyll b, leaf water content, and mid-day leaf water potential. The results suggest that CMNP at recommended concentrations (200 to 500 ppm) effectively reduced fruit attachment force with little herbicidal effect on leaves.

scholarly journals Silicon Application Increases Drought Tolerance of Kentucky Bluegrass by Improving Plant Water Relations and Morphophysiological Functions

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Shah Saud ◽  
Xin Li ◽  
Yang Chen ◽  
Lu Zhang ◽  
Shah Fahad ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Water Relations ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Plant Water Relations ◽  
Plant Water ◽  
Turf Quality

Drought stress encumbers the growth of turfgrass principally by disrupting the plant-water relations and physiological functions. The present study was carried out to appraise the role of silicon (Si) in improving the drought tolerance in Kentucky bluegrass (Poa pratensisL.). Drought stress and four levels (0, 200, 400, and 800 mg L−1) of Si (Na2SiO3·9H2O) were imposed after 2 months old plants cultured under glasshouse conditions. Drought stress was found to decrease the photosynthesis, transpiration rate, stomatal conductance, leaf water content, relative growth rate, water use efficiency, and turf quality, but to increase in the root/shoot and leaf carbon/nitrogen ratio. Such physiological interferences, disturbances in plant water relations, and visually noticeable growth reductions in Kentucky bluegrass were significantly alleviated by the addition of Si after drought stress. For example, Si application at 400 mg L−1significantly increased the net photosynthesis by 44%, leaf water contents by 33%, leaf green color by 42%, and turf quality by 44% after 20 days of drought stress. Si application proved beneficial in improving the performance of Kentucky bluegrass in the present study suggesting that manipulation of endogenous Si through genetic or biotechnological means may result in the development of drought resistance in grasses.

Leaf water relations of competitive Fagus sylvatica and Quercus petraea trees during 4 years differing in soil drought

2000 ◽  
Vol 30 (3) ◽  
pp. 335-346 ◽  
Author(s):  
K Backes ◽  
C Leuschner
Keyword(s):  
Water Relations ◽  
Water Status ◽  
Leaf Tissue ◽  
Quercus Petraea ◽  
Leaf Water ◽  
Soil Drought ◽  
Leaf Water Content ◽  
Leaf Water Relations ◽  
Four Seasons ◽  
Sun Leaves

Leaf water relations of competitive mature Fagus and Quercus trees were compared during four seasons with low, moderate, or high soil drought intensities in humid northwestern Germany. Leaf conductances (gl) typically were higher by about 30% in Quercus than in Fagus sun leaves. Predawn leaf water potentials (Ψpd) and osmotic potentials (Πo, Πp) were remarkably similar for the two species. Fagus had significantly lower leaf tissue elasticities (εmax) than Quercus in dry but not in wet summers. Interannual variabilities in water status parameters were large for gl and seasonal bulk leaf turgor (P) minima; moderate for εmax and daily water potential (Ψ) minima; and small for Πo, Πp, and the relative leaf water content at zero turgor. Fagus regulated water loss conservatively with only limited reductions in P and Ψ in wet or moderately dry seasons but large decreases in Ψpd,gl, photosynthesis, and growth during occasional severe droughts. Quercus displayed patterns of a stress-tolerating species (lower εmax, a less drought-sensitive stomatal regulation, and apparently significant drought-induced osmotic adjustment). In temperate humid environments, tree water relations should be studied for at least three or four seasons to account for large interannual variabilities in water status parameters.

scholarly journals Recovery from Phytotoxicity after Foliar Application of Fruit-loosening Abscission Compounds to Citrus

2008 ◽  
Vol 133 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Kuo-Tan Li ◽  
Jacqueline K. Burns ◽  
James P. Syvertsen
Keyword(s):  
Foliar Application ◽  
Sweet Orange ◽  
Fruit Growth ◽  
Mature Fruit ◽  
Photosystem Ii Efficiency ◽  
Young Fruit ◽  
Leaf Chlorophyll ◽  
Phytotoxic Effect ◽  
High Concentrations ◽  
Leaf Chlorophyll Fluorescence

The use of abscission compounds to loosen fruit from stems can be accompanied with various levels of phytotoxicity. To determine the effects of a promising abscission compound, 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), and ethephon on sweet orange [Citrus sinensis (L.) Osbeck] leaf function, water relations, and young fruit growth, we sprayed CMNP at 0, 200, 500, 1000, or 2000 mg·L−1 or ethephon at 400 or 800 mg·L−1 to fruiting branches of potted and field-grown sweet orange during the 2005–06 harvest season. Both compounds induced abscission of mature fruit and leaves 3 days after application but had little effect on leaf chlorophyll content, water content, and midday leaf water potential (Ψleaf) of remaining leaves. CMNP sprayed at 200 mg·L−1 or either concentration of ethephon did not affect leaf photosystem II efficiency, as indicated by leaf chlorophyll fluorescence (Fv/Fm). High CMNP concentrations (1000 or 2000 mg·L−1) reduced Fv/Fm 1 day after treatment, but Fv/Fm of leaves remaining on sprayed branches gradually recovered to the level of control leaves by 4 days after treatment. Similarly, high concentrations of CMNP and ethephon temporarily reduced net gas exchange of leaves for about 4 days. Young fruit growth also was temporarily inhibited by CMNP concentrations greater than 200 mg·L−1. We conclude that CMNP sprayed at recommended concentrations (200–500 mg·L−1) caused mature fruit abscission with little long-term phytotoxic effect on leaves or young fruit.

Water Relations of Field Grown Cotton and Sorghum: Temporal and Diurnal Changes in Leaf Water, Osmotic, and Turgor Potentials 1

Crop Science ◽  
1977 ◽  
Vol 17 (1) ◽  
pp. 76-80 ◽  
Author(s):  
R. C. Ackerson ◽  
D. R. Krieg ◽  
T. D. Miller ◽  
R. E. Zartman
Keyword(s):  
Water Relations ◽  
Leaf Water ◽  
Diurnal Changes

scholarly journals Leaf water content estimation using top-of-canopy airborne hyperspectral data

2021 ◽  
Vol 102 ◽  
pp. 102393
Author(s):  
Rahul Raj ◽  
Jeffrey P. Walker ◽  
Vishal Vinod ◽  
Rohit Pingale ◽  
Balaji Naik ◽  
...  
Keyword(s):  
Water Content ◽  
Hyperspectral Data ◽  
Leaf Water ◽  
Leaf Water Content

scholarly journals Simulating Heat Stress of Coal Gangue Spontaneous Combustion on Vegetation Using Alfalfa Leaf Water Content Spectral Features as Indicators

2021 ◽  
Vol 13 (13) ◽  
pp. 2634
Author(s):  
Qiyuan Wang ◽  
Yanling Zhao ◽  
Feifei Yang ◽  
Tao Liu ◽  
Wu Xiao ◽  
...  
Keyword(s):  
Heat Stress ◽  
Water Content ◽  
Spontaneous Combustion ◽  
Leaf Water ◽  
Coal Gangue ◽  
Leaf Water Content ◽  
Spectral Features ◽  
Lasso Regression ◽  
Stress Assessment ◽  
First Derivative

Vegetation heat-stress assessment in the reclamation areas of coal gangue dumps is of great significance in controlling spontaneous combustion; through a temperature gradient experiment, we collected leaf spectra and water content data on alfalfa. We then obtained the optimal spectral features of appropriate leaf water content indicators through time series analysis, correlation analysis, and Lasso regression analysis. A spectral feature-based long short-term memory (SF-LSTM) model is proposed to estimate alfalfa’s heat stress level; the live fuel moisture content (LFMC) varies significantly with time and has high regularity. Correlation analysis of the raw spectrum, first-derivative spectrum, spectral reflectance indices, and leaf water content data shows that LFMC and spectral data were the most strongly correlated. Combined with Lasso regression analysis, the optimal spectral features were the first-derivative spectral value at 1661 nm (abbreviated as FDS (1661)), RVI (1525,1771), DVI (1412,740), and NDVI (1447,1803). When the classification strategies were divided into three categories and the time sequence length of the spectral features was set to five consecutive monitoring dates, the SF-LSTM model had the highest accuracy in estimating the heat stress level in alfalfa; the results provide an important theoretical basis and technical support for vegetation heat-stress assessment in coal gangue dump reclamation areas.

Spectral assessments of wheat plants grown in pots and containers under saline conditions

2013 ◽  
Vol 40 (4) ◽  
pp. 409 ◽  
Author(s):  
Harald Hackl ◽  
Bodo Mistele ◽  
Yuncai Hu ◽  
Urs Schmidhalter
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Aboveground Biomass ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Spectral Indices ◽  
Fresh Weight ◽  
Normalised Difference Vegetation Index ◽  
Spectral Sensing ◽  
Reflectance Ratio

Spectral measurements allow fast nondestructive assessment of plant traits under controlled greenhouse and close-to-field conditions. Field crop stands differ from pot-grown plants, which may affect the ability to assess stress-related traits by nondestructive high-throughput measurements. This study analysed the potential to detect salt stress-related traits of spring wheat (Triticum aestivum L.) cultivars grown in pots or in a close-to-field container platform. In two experiments, selected spectral indices assessed by active and passive spectral sensing were related to the fresh weight of the aboveground biomass, the water content of the aboveground biomass, the leaf water potential and the relative leaf water content of two cultivars with different salt tolerance. The traits were better ascertained by spectral sensing of container-grown plants compared with pot-grown plants. This may be due to a decreased match between the sensors’ footprint and the plant area of the pot-grown plants, which was further characterised by enhanced senescence of lower leaves. The reflectance ratio R760 : R670, the normalised difference vegetation index and the reflectance ratio R780 : R550 spectral indices were the best indices and were significantly related to the fresh weight, the water content of the aboveground biomass and the water potential of the youngest fully developed leaf. Passive sensors delivered similar relationships to active sensors. Across all treatments, both cultivars were successfully differentiated using either destructively or nondestructively assessed parameters. Although spectral sensors provide fast and qualitatively good assessments of the traits of salt-stressed plants, further research is required to describe the potential and limitations of spectral sensing.

Effect of dust deposition on spectrum-based estimation of leaf water content in urban plant

2019 ◽  
Vol 104 ◽  
pp. 41-47 ◽  
Author(s):  
Wenpeng Lin ◽  
Yuan Li ◽  
Shiqiang Du ◽  
Yuanfan Zheng ◽  
Jun Gao ◽  
...  
Keyword(s):  
Water Content ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Dust Deposition

scholarly journals Spatial variation and mechanisms of leaf water content in grassland plants at the biome scale: evidence from three comparative transects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruomeng Wang ◽  
Nianpeng He ◽  
Shenggong Li ◽  
Li Xu ◽  
Mingxu Li
Keyword(s):  
Spatial Variation ◽  
Water Content ◽  
Large Scale ◽  
Life Forms ◽  
Important Variable ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Desert Grassland ◽  
Large Spatial Scale ◽  
Grassland Plants

AbstractLeaf water content (LWC) has important physiological and ecological significance for plant growth. However, it is still unclear how LWC varies over large spatial scale and with plant adaptation strategies. Here, we measured the LWC of 1365 grassland plants, along three comparative precipitation transects from meadow to desert on the Mongolia Plateau (MP), Loess Plateau, and Tibetan Plateau, respectively, to explore its spatial variation and the underlying mechanisms that determine this variation. The LWC data were normally distributed with an average value of 0.66 g g−1. LWC was not significantly different among the three plateaus, but it differed significantly among different plant life forms. Spatially, LWC in the three plateaus all decreased and then increased from meadow to desert grassland along a precipitation gradient. Unexpectedly, climate and genetic evolution only explained a small proportion of the spatial variation of LWC in all plateaus, and LWC was only weakly correlated with precipitation in the water-limited MP. Overall, the lasso variation in LWC with precipitation in all plateaus represented an underlying trade-off between structural investment and water income in plants, for better survival in various environments. In brief, plants should invest less to thrive in a humid environment (meadow), increase more investment to keep a relatively stable LWC in a drying environment, and have high investment to hold higher LWC in a dry environment (desert). Combined, these results indicate that LWC should be an important variable in future studies of large-scale trait variations.

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