Varietal differences in leaf water potential, leaf net CO2 assimilation, conductivity and water use efficiency in upland rice

1989 ◽  
Vol 40 (6) ◽  
pp. 1183 ◽  
Author(s):  
M Dingkuhn ◽  
Datta SK De ◽  
K Dorffling ◽  
C Javellana ◽  
SKde Datta
Keyword(s):  
Water Use Efficiency ◽  
Water Potential ◽  
Water Use ◽  
Upland Rice ◽  
Intercellular Co2 Concentration ◽  
Co2 Assimilation ◽  
The Philippines ◽  
Leaf Rolling ◽  
Net Co2 Assimilation ◽  
Use Efficiency

Twenty-eight rice (Oryza sativa L.) genotypes of different origin and habitat were grown in upland culture during the dry season in the Philippines. Irrigation was supplied by overhead sprinklers at a level which kept the crop under continuous mild water stress. Leaf net CO2 assimilation, conductivity, intercellular CO2 concentration, water potential and leaf rolling status were determined on the same leaf of all varieties between 0900 and 1200 hours during the vegetative growth stage.Leaf water potential ranged from -0.8 and -1.3 MPa, with japonica types showing the highest values, AUS types from Bangladesh, the lowest, and indica types intermediate. Leaf conductivity and leaf rolling did not differ significantly among these groups. Most cultivars showed a logarithmic relationship between net CO2 assimilation and conductivity. AUS cultivars had the lowest rates of leaf CO2assimilation, but no differences were observed between japonica and indica varieties. At a given intcercellular CO2concentration, net CO2 assimilation was lowest in AUS varieties, resulting in low water use efficiency, and possibly indicating a higher CO2 compensation point for AUS than for other rice types.

Net photosynthesis, water use efficiency, leaf water potential and leaf rolling as affected by water deficit in tropical upland rice

1989 ◽  
Vol 40 (6) ◽  
pp. 1171 ◽  
Author(s):  
M Dingkuhn ◽  
RT Cruz ◽  
JC O'Toole ◽  
K D÷rffling
Keyword(s):  
Water Use Efficiency ◽  
Water Potential ◽  
Water Deficit ◽  
Water Use ◽  
Leaf Water Potential ◽  
Upland Rice ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Leaf Rolling ◽  
Use Efficiency

Growth and production of tropical upland rice is often impeded by drought. Little is known on varietal response of CO2 assimilation to water deficit under tropical field conditions. A drought-susceptible semidwarf (IR20) and a drought-resistant traditional (Azucena) rice were grown in a dryland field experiment with sprinkler irrigation during the dry season in the Philippines. Differential irrigation was imposed for 11 days during vegetative growth using a line source sprinkler. Net photosynthesis, leaf conductance, transpiration, leaf rolling and leaf water potential were determined during the stress cycle at pre-noon and afternoon, with all measurements on the same leaf. No varietal differences in maximum photosynthetic rate and in the relationship between photosynthesis and leaf conductance were observed. In both rices, partial stomatal closure and nonstomatal inhibition reduced assimilation rates in the afternoon. Leaf water deficits restricted gas exchange through at least three apparently independent mechanisms: leaf rolling, reduced stomatal conductance and non-stomata1 inhibition which became evident only at severe degrees of stress. Stomata1 closure and leaf rolling were more sensitive to water deficit in Azucena which maintained higher leaf water potential throughout the stress cycle. Both stomatal closure and leaf rolling improved water use efficiency at moderate stress while nonstomatal inhibition of photosynthesis reduced water use efficiency.

scholarly journals Water Use Efficiency in Popcorn (Zea mays L. var. everta): Which Physiological Traits Would Be Useful for Breeding?

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1450
Author(s):  
Jhean Torres Leite ◽  
Antonio Teixeira do Amaral Junior ◽  
Samuel Henrique Kamphorst ◽  
Valter Jário de Lima ◽  
Divino Rosa dos Santos Junior ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Chlorophyll Concentration ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Inbred Lines ◽  
Experimental Unit ◽  
Root Angle ◽  
Net Co2 Assimilation ◽  
Use Efficiency

To ensure genetic gains in popcorn breeding programs carried out under drought conditions knowledge about the response of morphophysiological traits of plants to water stress for the selection of key traits is required. Therefore, the objective was to evaluate popcorn inbred lines with agronomically efficient (P2 and P3) and inefficient (L61 and L63) water use and two hybrids (P2xL61 and P3xL63) derived from these contrasting parents, cultivated under two water regimes (WW watered—WW; and water-stressed—WS) in a greenhouse, replicated five times, where each experimental unit consisted of one plant in a PVC tube. Irrigation was applied until stage V6 and suspended thereafter. Individual and combined analyses of variance were performed and the genotypic correlations and relative heteroses estimated. The water use efficient inbred lines were superior in root length (RL), root dry weight (RDW), and net CO2 assimilation rate (A), which were the characteristics that differentiated the studied genotypes most clearly. High heterosis estimates were observed for RL, SDW, leaf width (LW), leaf midrib length (LL), and agronomic water use efficiency (AWUE). The existence of a synergistic association between root angle and length for the characteristics A, stomatal conductance (gs), and chlorophyll concentration (SPAD index) proved most important for the identification and phenotyping of superior genotypes. Based on the study of these characteristics, the higher AWUE of the previously selected inbred lines could be explained. The results reinforced the importance of root physiological and morphological traits to explain AWUE and the possibility of advances by exploiting heterosis, given the morphophysiological superiority of hybrids in relation to parents.

scholarly journals GROWTH AND PHYSIOLOGICAL RESPONSE OF COFFEE SEEDLINGS TREATED WITH FUNGICIDES

2019 ◽  
Vol 14 (2) ◽  
pp. 138 ◽  
Author(s):  
Viviane Maria Ruela ◽  
Adriano Bortolotti da Silva ◽  
André Delly Veiga ◽  
Thiago Corrêa de Souza ◽  
Daniele Maria Marques ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Fresh Matter ◽  
Fungicidal Action ◽  
Positive Effects ◽  
Use Efficiency ◽  
Intercellular Co2

Research has shown that, in addition to the fungicidal action already known, strobilurins have positive physiological effects on the yield of some crops. Boscalid has also shown positive effects on plants, applied together or associated with strobilurin. The objective in this study was to evaluate the effect of fungicide application on growth and physiological behavior of coffee seedlings. The experimental design was in randomized blocks, with five replicates. There were five treatments: T1-Control, T2-Boscalid, T3-Pyraclostrobin, T4- Boscalid+ Pyraclostrobin and T5- Azoxystrobin applied in coffee seedlings. The application was at the “orelha de onça” stage (two round-shaped leaves), repeated every 15 days, counting 5 applications in total. Were evaluated shoot length, root length, stem diameter, shoot and root fresh matter, shoot and root dry matter, leaf photosynthesis, stomatal conductance, transpiration, intercellular CO2 concentration, water use efficiency and carboxylation efficiency. The application of fungicides promotes greater vegetative growth of coffee seedlings due to increased CO2 assimilation rate, reduced transpiration rates and increased water use efficiency, associated to the increased levels of auxin and cytokinins in leaves

Discrimination of 13C among upland rices having different water use efficiencies

1991 ◽  
Vol 42 (7) ◽  
pp. 1123 ◽  
Author(s):  
M Dingkuhn ◽  
GD Farquhar ◽  
Datta SK De ◽  
JC O'Toole ◽  
SKde Datta
Keyword(s):  
Water Use Efficiency ◽  
Carbon Isotope ◽  
Water Use ◽  
Carbon Isotope Discrimination ◽  
Upland Rice ◽  
Oryza Sativa L ◽  
The Philippines ◽  
N Content ◽  
Isotope Discrimination ◽  
Use Efficiency

Discrimination of stable carbon isotopes in leaves is physiologically linked to water-use efficiency. Twenty-eight contrasting rice (Oryza sativa L.) cultivars were grown in the Philippines as upland rice under continuous, mild water stress. In situ measurements of leaf level water-use efficiency (WUE), net photosynthesis, conductance, water potential and leaf rolling were reported previously. The present study used leaf samples from the same experiment to determine, by means of a mass spectrometer, the carbon isotope discrimination (-) and total C and N content. Among rice cultivars, - ranged from 19.8 to 21.5960, with japonica types having the lowest mean -, aus types, the greatest, and indica types, intermediate-the opposite pattern to that observed for WUE. Carbon isotope discrimination was negatively correlated with WUE across all cultivars (P < 0.001) and within japonica (P < 0 -01) and aus (P < 0.05) groups, but not among indica rices. No correlation was observed between - and any other measured variable. Varietal differences in - and WUE were not related to leaf N content or stomata1 conductance. High WUE was associated with high leaf C content (P < 0.01), with aus cultivars having the lowest mean WUE and C content among the genetic groups. We conclude that even under variable field conditions, analysis of foliar - is a potential tool to identify water-use efficient rice genotypes.

Diurnal Time Course of Leaf Gas Exchange Rates and Related Characters in Drought-Acclimated and Irrigated Trifolium Subterraneum.

1995 ◽  
Vol 22 (3) ◽  
pp. 461 ◽  
Author(s):  
J Vadell ◽  
C Cabot ◽  
H Medrano
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Water Use Efficiency ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Trifolium Subterraneum ◽  
Co2 Assimilation ◽  
Carbon Gain ◽  
Assimilation Rate ◽  
Use Efficiency

The effects of drought acclimation on the diurnal time courses of photosynthesis and related characters were studied in Trifolium subterraneum L. leaves during two consecutive late spring days. Leaf CO2 assimilation rate and transpiration rate followed irradiance variations in irrigated plants. Under drought, a bimodal pattern of leaf CO2 assimilation rate developed although stomatal conductance remained uniform and low. Instantaneous water-use efficiency was much higher in droughted plants during the early morning and late evening, while during the middle of the day it was close to the value of irrigated plants. Net carbon gain in plants under drought reached 40% of the carbon gain in irrigated plants with a significant saving of water (80%). Average data derived from midday values of leaf CO2 assimilation rates and instantaneous water-use efficiency did not provide good estimates of the daily carbon gain and water-use efficiency for droughted leaves. Coupled with the morphological changes as a result of acclimation to progressive drought, modifications of diurnal patterns of leaf gas exchange rates effectively contribute to a sustained carbon gain during drought. These modifications significantly improve water-use efficiency, mainly by enabling the plant to take advantage of morning and evening hours with high air humidity.

scholarly journals The Effect of Night Temperature on Co2 Assimilation, Transpiration, and Water Use Efficiency in Agave Americana L

1973 ◽  
Vol 26 (4) ◽  
pp. 705 ◽  
Author(s):  
TF Neales
Keyword(s):  
Water Use Efficiency ◽  
Water Vapour ◽  
Water Use ◽  
Nutrient Solution ◽  
Co2 Assimilation ◽  
Night Temperature ◽  
Agave Americana ◽  
Use Efficiency ◽  
Water Vapour Fluxes

The CO2 and water vapour fluxes arising from the tops of a plant of A. americana, growing in nutrient solution, were continuously measured at night temperatures of 15, 25, and 36�C, the day temperature being held constant at 25�C.

Effect of water stress on growth, water use efficiency and gas exchange as related to osmotic adjustment of two halophytes Atriplex spp.

2013 ◽  
Vol 40 (5) ◽  
pp. 466 ◽  
Author(s):  
Oumelkheir Belkheiri ◽  
Maurizio Mulas
Keyword(s):  
Water Stress ◽  
Water Use Efficiency ◽  
Water Use ◽  
Osmotic Adjustment ◽  
Late Summer ◽  
Field Capacity ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Effect Of Water ◽  
Use Efficiency

Atriplex halimus L. is known in the Mediterranean basin and along the coastal areas of Sardinia for its adaptability to salinity, although less information is available on the resistance of this species to water stress in absence of salinity. The effect of water stress on growth and water utilisation was investigated in two Atriplex species: A. halimus originating of south Sardinian island and the exotic species Atriplex nummularia Lindl., originating in Australia and widely used in land restoration of arid areas. Water stress was applied to young plants growing in 20 L pots with a sufficient water reserve to store a potentially sufficient water reserve to maintain substrate near to field capacity (30%) between irrigations. Watering was at 70% (control) or 40% (stress) of field capacity. In order to simulate the grazing by livestock, four plant biomass cuttings were conducted at times T0, T1, T2 and T3, corresponding to one cutting at the end of well watered phase (T0) before water stress induction, two cuttings after cycles of 5 weeks each during full summer (T1) and late summer (T2) and one cutting during autumn (T3). All plants remained alive until the end of treatment although growth was strongly reduced. Leaf dry weight (DW) and water use efficiency (WUE) were determined for all cuttings; relative water content (RWC), turgid weight : dry weight ratio (TW : DW), water potential (Ψw), osmotic potential (Ψs), CO2 assimilation, osmotic adjustment (OA), abscisic acid (ABA) and sugar accumulation were determined for the late summer cutting at T2. Water stress induced a decrease in DW, RWC, Ψw, Ψs, TW : DW and CO2 assimilation for both species, but an increase in WUE expressed in terms of dry matter production and a high accumulation of ABA and total sugars mainly for A. halimus. This suggests a more developed adaptive mechanism in this selection. Indeed, the clone was selected from the southern part of the island, where natural populations of saltbush are more exposed to abiotic stresses, mainly the water stress generated not by salinity. A. nummularia showed a greater OA and a positive net solute accumulation as than A. halimus, suggesting that water stress resistance in A. halimus is linked to a higher WUE rather than a greater osmotic adjustment.

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