scholarly journals The direct and indirect effects of nitrogen shortage on photosynthesis and transpiration in maize and sunflower.

1979 ◽  
Vol 27 (3) ◽  
pp. 227-234
Author(s):  
J. Goudriaan ◽  
H. van Keulen
Keyword(s):  
Indirect Effects ◽  
Leaf Tissue ◽  
Co2 Assimilation ◽  
Direct And Indirect Effects ◽  
Stomatal Behaviour ◽  
Net Co2 Assimilation ◽  
Similar Relation ◽  
Use Efficiency ◽  
Different Levels ◽  
N Status

Experiments with maize and sunflower in sol. culture were carried out to investigate the effect of N shortage in the leaf tissue on stomatal behaviour. In maize a linear relation existed between the rate of net CO2 assimilation and the conductance of water vapour, independently of the N status of the tissue. In sunflower a similar relation existed although the evidence was less conclusive. It was concluded that stomatal behaviour cannot explain differences in water-use efficiency between plants growing at different levels of N. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Harnessing phenotypic networks and structural equation models to improve genome-wide association analysis

2019 ◽  
Author(s):  
Mehdi Momen ◽  
Malachy T. Campbell ◽  
Harkamal Walia ◽  
Gota Morota
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Indirect Effects ◽  
Root Biomass ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Genome Wide Association ◽  
Direct And Indirect Effects ◽  
Genome Wide ◽  
Use Efficiency

AbstractPlant breeders and breeders alike seek to develop cultivars with maximal agronomic value. The merit of breeding material is often assessed using many, often genetically correlated traits. As intervention on one trait will affect the value of another, breeding decisions should consider the relationships between traits. With the proliferation of multi-trait genome-wide association studies (MTM-GWAS), we can infer putative genetic signals at the multivariate scale. However, a standard MTM-GWAS does not accommodate the network structure of phenotypes, and therefore does not address how the traits are interrelated. We extended the scope of MTM-GWAS by incorporating phenotypic network structures into GWAS using structural equation models (SEM-GWAS). In this network GWAS model, one or more phenotypes appear in the equations for other phenotypes as explanatory variables. A salient feature of SEM-GWAS is that it can partition the total single nucleotide polymorphism (SNP) effects into direct and indirect effects. In this paper, we illustrate the utility of SEM-GWAS using biomass, root biomass, water use, and water use efficiency in rice. We found that water use efficiency is directly impacted by biomass and water use and indirectly by biomass and root biomass. In addition, SEM-GWAS partitioned significant SNP effects influencing water use efficiency into direct and indirect effects as a function of biomass, root biomass, and water use efficiency, providing further biological insights. These results suggest that the use of SEM may enhance our understanding of complex relationships between GWAS traits.

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.

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.

scholarly journals Gas exchange and yield response to foliar phosphorus application in Phaseolus vulgaris L. under drought

2004 ◽  
Vol 16 (3) ◽  
pp. 171-179 ◽  
Author(s):  
Mauro Guida dos Santos ◽  
Rafael Vasconcelos Ribeiro ◽  
Ricardo Ferraz de Oliveira ◽  
Carlos Pimentel
Keyword(s):  
Gas Exchange ◽  
Water Deficit ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Yield Response ◽  
Net Co2 Assimilation ◽  
Foliar Phosphorus ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Phosphorus Application

This study was conducted to evaluate the effect of foliar Pi application on gas exchange and yield of bean genotypes submitted to a mild water deficit at the pre-flowering stage. In the first experiment, when extra Pi (10 g.L-1) was sprayed on leaves during water stress or during recovery, there was no effect on gas exchange or yield in the A320, Carioca and Ouro Negro genotypes. However, net CO2 assimilation (A) of A320 and Ouro Negro was less affected, but not significantly, than Carioca at the end of the stress, when Pi was supplied five days before water deficit. In the second experiment, two different doses of Pi (10 and 20 g.Pi L-1) were sprayed five days before water deficit on the Carioca genotype. During the last three days of the mild water deficit, A values were significantly higher for the Pi20 treatment when compared to the control plants without extra Pi supply. The intrinsic water use efficiency for plants receiving Pi20 was significantly higher than for the other treatments. In addition, seed dry weight per plant was higher for plants receiving Pi20 dose than for plants with Pi10 and its control.

scholarly journals Physiological and Molecular Responses of ‘Dusa’ Avocado Rootstock to Water Stress: Insights for Drought Adaptation

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2077
Author(s):  
Moreno-Ortega Guillermo ◽  
Zumaquero Adela ◽  
Matas Antonio ◽  
Nicholas A. Olivier ◽  
van den Berg Noëlani ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Availability ◽  
Redox Homeostasis ◽  
Field Capacity ◽  
Molecular Data ◽  
Co2 Assimilation ◽  
Functional Enrichment ◽  
Molecular Responses ◽  
Net Co2 Assimilation ◽  
Different Levels

Avocado consumption is increasing year by year, and its cultivation has spread to many countries with low water availability, which threatens the sustainability and profitability of avocado orchards. However, to date, there is not much information on the behavior of commercial avocado rootstocks against drought. The aim of this research was to evaluate the physiological and molecular responses of ‘Dusa’ avocado rootstock to different levels of water stress. Plants were deficit irrigated until soil water content reached 50% (mild-WS) and 25% (severe-WS) of field capacity. Leaf water potential (w), net CO2 assimilation rates (AN), transpiration rate (E), stomatal conductance (gs), and plant transpiration rates significantly decreased under both WS treatments, reaching significantly lower values in severe-WS plants. After rewatering, mild- and severe-WS plants showed a fast recovery in most physiological parameters measured. To analyze root response to different levels of drought stress, a cDNA avocado stress microarray was carried out. Plants showed a wide transcriptome response linked to the higher degree of water stress, and functional enrichment of differentially expressed genes (DEGs) revealed abundance of common sequences associated with water stress, as well as specific categories for mild-WS and severe-WS. DEGs previously linked to drought tolerance showed overexpression under both water stress levels, i.e., several transcription factors, genes related to abscisic acid (ABA) response, redox homeostasis, osmoprotection, and cell-wall organization. Taken altogether, physiological and molecular data highlight the good performance of ‘Dusa’ rootstock under low-water-availability conditions, although further water stress experiments must be carried out under field conditions.

scholarly journals Influence of mechanical root restriction on gas-exchange of four papaya genotypes

2001 ◽  
Vol 13 (2) ◽  
pp. 129-138 ◽  
Author(s):  
ELIEMAR CAMPOSTRINI ◽  
OSVALDO KIYOSHI YAMANISHI
Keyword(s):  
Gas Exchange ◽  
Co2 Assimilation ◽  
Leaf Temperature ◽  
Maximum Pressure ◽  
Assimilation Rate ◽  
Net Co2 Assimilation ◽  
Intrinsic Water Use Efficiency ◽  
Partial Pressure Of Co2 ◽  
Use Efficiency ◽  
Root Restriction

Four papaya genotypes, two from the ‘Solo’ group (Sunrise Solo TJ and Improved Sunrise Solo line 72/12) and two from the ‘Formosa’ group (Tainung 02 and Know You 01) grown in ultisol under field conditions in Macaé, RJ, Brazil, were used in this study. Two different effective depths (ED) were determined in the area using a penetrographer with average soil moisture of 11.2%. The area with ED of 0.35 m with a maximum pressure of 4.12 MPa for penetration was defined as an area with restriction (WR) to root growth, while, the area with minimum ED of 0.60 m and a pressure lower than 2.30 MPa as an area with no restriction (NR). The net CO2 assimilation rate (A), stomatal conductance (g s), leaf temperature (Tl), intercellular partial pressure of CO2 (c i) and intrinsic water use efficiency (IWUE) were evaluated for three consecutive days after irrigation. Mechanical root restriction affected gas exchange of the four papaya genotypes. All genotypes grown in the WR area had lower A, g s and c i and higher Tl than the same genotypes in the NR area. All genotypes grown in the WR area had high IWUE and Sunrise Solo TJ had the highest IWUE.

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