scholarly journals Response of Gas Exchange to Leaf Piercing Explained by Piecewise Linear Regression for Two Developmental Forms of Rape Plant (Brassica napus L. ssp. oleifera Metzg)

2017 ◽  
Vol 59 (1) ◽  
pp. 81-92
Author(s):  
Anna Wenda-Piesik ◽  
Włodzimierz Krzesiński ◽  
Agnieszka Nowak ◽  
Maciej Kazek ◽  
Magdalena Tomaszewska-Sowa
Keyword(s):  
Brassica Napus ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Linear Regression ◽  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Piecewise Linear ◽  
Exchange Process ◽  
Gas Exchange Parameters ◽  
Piecewise Linear Regression

AbstractOilseed rape (Brassica napusL. ssp.oleiferaMetzg) was the subject of the study in two forms: wintercv. ‘Muller’ (at the rosette stage – the first internode BBCH 30 – 31) and springcv. ‘Feliks’ (at the yellow bud stage BBCH 59). The main gas-exchange parameters, net photosynthetic rate (PN), transpiration rate (E), stomatal conductance (gs), and intercellular CO2concentration (Ci) were measured on leaves prior to the piercing and immediately after the short-term piercing. The effect of mechanical wounding revealed different progress of the gas exchange process for the two forms. Piecewise linear regression with the breakpoint estimation showed that the plants at the same age but at a different vegetal stage, manage mechanical leaf-piercing differently. The differences concerned the stomatal conductance and transpiration changes since for rosette leaves the process consisted of five intervals with a uniform direction, while for stem leaves - of five intervals with a fluctuating direction. These parameters got stabilized within a similar time (220 mins) for both forms. The process of net photosynthetic rate was altered by the plant stages. ‘Muller’ plants at the rosette stage demonstrated dependence ofPNon time inlog-linear progression: y (PN) = 8.01 + 2.73 log10(x t2); 7 < t2< 220;R2= 0.96. For stem leaves of ‘Feliks’ plants the process of transpiration, in terms of directions, was convergent with the process of photosynthesis. Those two processes were synchronized from 1stto 114thmin of the test (r= 0.85;p< 0.001) in plants at the rosette stage and from 26thto 148thmin in stem leaves (r= 0.95;p< 0.001).

scholarly journals Effect of drought on gas exchange and chlorophyll fluorescence of groundnut genotypes

2021 ◽  
Vol 13 (4) ◽  
pp. 1478-1487
Author(s):  
K. Manojkumar ◽  
S. Vincent ◽  
M. Raveendran ◽  
R. Anandham ◽  
V. Babu Rajendra Prasad ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Water Deficit Stress ◽  
Abiotic Factor ◽  
Gas Exchange Parameters ◽  
Ps Ii

Drought is one of the major threats to groundnut productivity, causing a greater loss than any other abiotic factor. Water stress conditions alter plant photosynthetic activity, impacting future growth and assimilating mobilization towards sink tissues. The purpose of this study was to investigate how drought impacts the photosynthesis of plants and its links to drought tolerance. The influence of reproductive stage drought on photosynthetic activity and chlorophyll fluorescence of groundnut is well studied. The experiment was conducted in Kharif 2019 (Jul-Sep), where recent series in groundnut genotypes (60 nos) sown under rainfed conditions and water stress was created by withholding irrigation for 20 days between 35-55 days after sowing in the field to simulate drought conditions. Imposition of water deficit stress reduced PS II efficiency, which significantly altered the photosynthetic rate in the leaf. Observation of gas exchange parameters viz., photosynthetic rate, stomatal conductance and transpiration rate after 20 days of stress imposition revealed that of all 60 genotypes, 20 genotypes (VG 17008, VG 17046VG 18005, VG 18102, VG 18077, VG 19572, VG 19709, VG 18111, VG19561, VG19576, VG 19620, VG 19681, VG 19688, etc.,) had better Photosynthetic rate, Stomatal conductance. Similarly, PS II efficiency analyzed through fluorescence meter revealed that among the 60 and all the genotypes given above recorded higher value in Fv/Fm. Results obtained from Cluster analysis and PCA confirmed that photosynthetic rate and Fv/Fm is useful parameter in screening adapted cultivars under drought stress. These findings lay the groundwork for a future study to decipher the molecular pathways underpinning groundnut drought resistance.

Gas exchange and yield in Miscanthus species for three years at two locations in Poland

2013 ◽  
Vol 93 (4) ◽  
pp. 627-637 ◽  
Author(s):  
Katarzyna Głowacka ◽  
Stanisław Jeżowski ◽  
Zygmunt Kaczmarek
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Photosynthetic Rate ◽  
Correlation Coefficients ◽  
Regression Analyses ◽  
Gas Exchange Parameters ◽  
The Third ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Exchange Parameters

Głowacka, K., Jeżowski, S. and Kaczmarek, Z. 2013. Gas exchange and yield in Miscanthus species for three years at two locations in Poland. Can. J. Plant Sci. 93: 627–637. The influence of gas exchange parameters on yields of six Miscanthus clones were evaluated in two locations over three years. Five out of six genotypes had significant increases in the photosynthetic rate and intrinsic water use efficiency between the third and first or third and second years, while intercellular CO2 concentration and stomatal conductance decreased. In addition, the multiple regression analyses of yields on parameters showed that the type of the correlation coefficients for transpiration, stomatal conductance and intercellular CO2 concentration varied throughout the years. The strongest correlation (0.86) between yield and photosynthetic rate was found for 3-year-old plants.

scholarly journals Effect of Soil Applied Silicon on Gas Exchange Parameters, Growth and Ion Content of Maize under Alkaline Stress

2021 ◽  
Vol 12 (1) ◽  
pp. 032-039
Author(s):  
Gokula Priya Natarajan ◽  
◽  
Malayappa Venkataraman Sriramachandrasekharan ◽  
Rengarjan Manivannan ◽  
Muthu Arjuna Samy Prakash ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Chlorophyll Content ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Root Length ◽  
Alkaline Stress ◽  
Ion Content ◽  
Gas Exchange Parameters ◽  
Exchange Parameters

A pot experiment was conducted to understand the effect of soil applied silicon on maize crop growth under alkaline stress. The treatment consists of silicon levels (kg ha-1) – 0, 100 and 150 and alkaline stress levels (mM) – 0, 25, 50, 75. The pots were arranged in completely randomized block design in factorial arrangement with three replications. The result revealed that the shoot and root length and chlorophyll content of maize were reduced with increasing alkaline stress. The percent reduction due to alkaline stress on shoot and root length was to tune of 3.6 to 15.8 and 8.9 to 35.8, respectively and chlorophyll content 11.2 to 35.7. The sodium ion content increased, but potassium content and K Na-1 ratio decreased with alkaline stress. The gas exchange parameters viz., photosynthetic rate, stomatal conductance and transpiration rate were significantly decreased with alkalinity levels. The adverse effect of alkalinity on maize was turnround with intervention of soil applied silicon. The percent increase due to silicon intervention ranged from 4.3 to 12.6 in photosynthetic rate, 4.5 to 14.5 in stomatal conductance, 6.3 to 21.4 in transpiration rate, 7.0 to 20.9 and 8.4 to 29.3 in shoot and root potassium, 19.4 to 33.5 and 20.6 to 55.9 in shoot and root K Na-1. The percent decrease in sodium concentration in shoot and root ranged from 8.6 to 14.2 and 4.3 to 23.7. Between 100 and 150 kgs of silicon applied, the desired result was achieved with 150 kg Si ha-1. It is recommended to apply 150 kg Si ha-1 to maneuver the ill effects of alkalinity on maize.

Identifying changes in trends in the age standardized incidence of melanoma in Australia

2019 ◽  
Vol 3 (4) ◽  
pp. 250-252 ◽  
Author(s):  
David M Hille
Keyword(s):  
Public Health ◽  
Linear Regression ◽  
Iterative Process ◽  
Linear Trend ◽  
Piecewise Linear ◽  
Health Issue ◽  
Public Health Issue ◽  
Piecewise Linear Regression ◽  
Significant Public Health ◽  
Males And Females

ObjectiveTo identify changes in the linear trend of the age-standardized incidence of melanoma in Australia for all persons, males, and females. MethodsA two-piece piecewise linear regression was fitted to the data. The piecewise breakpoint varied through an iterative process to determine the model that best fits the data.ResultsStatistically significant changes in the trendof the age-standardized incidence of melanoma in Australia were found for all persons, males, and females. The optimal breakpoint for all persons and males was at 1998. For females, the optimal breakpoint was at 2005. The trend after these breakpoints was flatter than prior to the breakpoints, but still positive.ConclusionMelanoma is a significant public health issue in Australia. Overall incidence continues to increase. However, the rate at which the incidence is increasing appears to be decreasing.

scholarly journals Response of in vitro Cultured Palm Oil Seedling Under Saline Condition to Elevated Carbon Dioxide and Photosynthetic Photon Flux Density

2012 ◽  
pp. 52-64
Author(s):  
Pet Roey Pascual ◽  
Krienkai Mosaleeyanon ◽  
Kanokwan Romyanon ◽  
Chalermpol Kirdmanee
Keyword(s):  
Stomatal Conductance ◽  
Net Photosynthetic Rate ◽  
Elevated Co2 ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Pigment Contents ◽  
Salinity Levels ◽  
Oil Palms ◽  
Ambient Co2

Salt stress elicits various physiological and growth responses of oil palm. A laboratory experiment was conducted to determine the responses of oil palms cultured in vitro under varying salinity levels (0, 85.5, 171.11, 342.21 and 684.43 mM NaCl) to elevated CO2 (1000 μmol CO2/mol) and PPFD (100±5 μmol m-2s-1) in terms of growth characteristics, pigment contents and photosynthetic abilities. After 14 days of culture, net photosynthetic rate (μmol CO2 m-2s-1) of oil palms across varying salinity levels was 5.33 times higher than those cultured under ambient CO, (380±100 Mmol CO2/mol) and PPFD (50±5 μmol m-2s -1). At increased net photosynthetic rate (elevated CO2 and PPFD), despite having no significant difference in pigment contents (chlorophyll a, chlorophyll b, total chlorophyll and carotenoid) between different CO2 and PPFD levels, dry weight and percent dry matter were 0.26 and 0.11 times higher, respectively, as compared to those cultured under ambient CO2 and PPFD. In the same elevated CO2 and PPFD level, across all salinity levels, stomatal conductance was 0.30 times lower than those cultured under ambient CO2 and PPFD. At reduced stomatal conductance (elevated CO2 and PPFD), transpiration rate was also reduced by 0.30 times. Thus with increased net photosynthetic rate and reduced transpiration rate, water use efficiency was increased by 7.22 times, across all salinity levels, than those cultured at ambient CO2 and PPFD. These were considered essential for NaCl produces iso-osmotic stress.

U-Shaped Association Between the Triglycerides-Glucose index and the Risk of Incident Diabetes in Apparently Healthy Population: A Population-based Cohort Study

2020 ◽  
Author(s):  
Xiuping Xuan ◽  
Masahide Hamaguchi ◽  
Qiuli Cao ◽  
Okamura Takuro ◽  
Yoshitaka Hashimoto ◽  
...  
Keyword(s):  
Linear Regression ◽  
Regression Model ◽  
Linear Regression Model ◽  
Piecewise Linear ◽  
Incident Diabetes ◽  
Smoothing Function ◽  
Healthy Population ◽  
Piecewise Linear Regression ◽  
Tyg Index ◽  
Apparently Healthy

Abstract Background Although the triglycerides-glucose (TyG) index was thought to be a practical predictor of incident diabetes, the association between them has not been well characterized. The study aimed to further examine the association between the TyG index and incident diabetes in Japanese adults. Methods The cases were extracted of the individual participating in the NAGALA (NAfld in the Gifu Area, Longitudinal Analysis) study at Murakami Memorial Hospital from 2004 to 2015, and 14297individuals apparently healthy at baseline were included in the study. Cox proportional hazards models were used to evaluate the associations between baseline TyG levels and incident of T2DM, and a two-piecewise linear regression model was use to examine the threshold effect of the baseline TyG on incident diabetes using a smoothing function. The threshold level (i.e., turning point) was determined using trial and error. A log likelihood ratio test was also conducted to compare the one-line linear regression model with a two-piecewise linear model. Results During a median follow-up period of 5.26 (women) and 5.88 (men) years, 47 women and 182 men developed Type 2 diabetes. The risk of diabetes was strongly associated with the baseline TyG index in the fully adjusted model in men but not in women, and no dose-dependent positive relationship between incident diabetes and TyG was observed across TyG tertiles. Intriguingly, two-piecewise linear regression analysis showed a U-shaped association between the TyG index and incident T2DM. The risk of incident diabetes decreased by around 90% in women with TyG < 7.27 (HR: 0.09; P = 0.0435) and 80% in men with TyG < 7.97 (HR 0.21, P = 0.002) with each increment of the TyG index after adjusting for confounders. In contrast, the risk of incident T2DM significantly elevated with the increase in TyG index in men with TyG > 7.97 (HR: 2.42, P < 0.001) and women with TyG > 7.29 (HR 2.76, P = 0.0166). Conclusions A U-shaped association was observed between the TyG index and incident T2DM among healthy individuals, with the TyG threshold of 7.97 in men and 7.27 in women. This information may be useful for reducing incident diabetes by maintaining the TyG index near these thresholds.

scholarly journals Effects of the reciprocal grafting on the photosynthesis of two genotypes tomato offspring under selenium stress

2019 ◽  
Vol 136 ◽  
pp. 07008
Author(s):  
Shiyao Shan ◽  
Huizhong Luo ◽  
Jinpeng Zhu ◽  
Zhiyu Li ◽  
Huanxiu Li
Keyword(s):  
Stomatal Conductance ◽  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Functional Activity ◽  
Theoretical Basis ◽  
Photosynthetic Capacity ◽  
Growth Characteristics ◽  
Cherry Tomato ◽  
Fresh Weight

To study the effects of the reciprocal grafting on the photosynthesis of two genotypes tomato offspring under selenium stress, red ball cherry tomato cherry 5-5-1 and yellow ball cherry tomato yellow RTY-3-2 post-grafting generation (red scion, red rootstock, yellow scion and yellow rootstock) and seedlings (red CK and yellow CK) planted in 10 mg·kg-1 selenium soil, and the pot experiment was carried out to study the effects of the reciprocal grafting on the growth characteristics and the photosynthesis of tomato offspring under selenium stress. The results showed that grafting increased the fresh weight of the organs of the offspring, the ratio of root to shoot, and the functional activity of the roots of the plants, which was conducive to the growth of tomato offspring. Simultaneously, it could effectively improve the photosynthetic capacity of grafted offspring leaves at the seedling stage. The grafted offspring of rootstocks had the best effect on improving the net photosynthetic rate, stomatal conductance and transpiration rate and stomatal conductance of tomato leaves, and decreased intercellular CO2 concentration. Among them, the best effect of yellow rootstock was to provide ideas and theoretical basis for the production of selenium-enriched tomatoes in the selenium-deficient areas in the future.

scholarly journals Mitigation of Osmotic Stress in Cotton for the Improvement in Growth and Yield through Inoculation of Rhizobacteria and Phosphate Solubilizing Bacteria Coated Diammonium Phosphate

2020 ◽  
Vol 12 (24) ◽  
pp. 10456
Author(s):  
Muhammad Majid ◽  
Muqarrab Ali ◽  
Khurram Shahzad ◽  
Fiaz Ahmad ◽  
Rao Muhammad Ikram ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Osmotic Stress ◽  
Net Photosynthetic Rate ◽  
Plant Height ◽  
Photosynthetic Rate ◽  
Diammonium Phosphate ◽  
Cotton Yield ◽  
Seed Cotton ◽  
Seed Cotton Yield ◽  
Boll Weight

Cotton (Gossypium hirsutum L.) is one of the major fiber crops. Its production is under threat due to scarcity of water resources under a changing climatic scenario. Limited water availability also decreases the uptake of phosphorus, and less uptake of phosphorus can deteriorate the quality attributes of cotton fiber. There is a need to introduce bio-organic amendments which can mitigate osmotic stress on a sustainable basis. Inoculation of rhizobacteria can play an imperative role in this regard. Rhizobacteria can not only improve the growth of roots but also enhance the availability of immobile phosphorus in soil. That is why the current experiment was conducted to explore and compare the efficacy of sole application of diammonium phosphate (DAP) over plant growth-promoting rhizobacteria (PGPR) and phosphorus solubilizing bacteria (PSB) coated DAP on growth and quality attributes of cotton under artificially induced osmotic stress at flowering stage. The impact of phosphorus levels was found to be significant on the plant height, leaf area, average boll weight, stomatal conductance, net photosynthetic rate, and seed cotton yield, while the irrigation effect was significant on all the parameters. The PGPR coated phosphorus performed better as compared to other treatments under normal irrigation and osmotic stress. Results showed that PGPR coated phosphorus increased by 29.47%, 21.01%, 41.11%, 32.73%, 15.63% and 22.89% plant height, average boll weight, stomatal conductance, net photosynthetic rate, fiber length, and seed cotton yield respectively. In conclusion, PGPR coated DAP can be helpful to get higher cotton productivity as compared to control and sole application of DAP under normal irrigation and osmotic stress.

scholarly journals Piecewise Linear Regression Based on Plane Clustering

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 29845-29855 ◽  
Author(s):  
Xubing Yang ◽  
Hongxin Yang ◽  
Fuquan Zhang ◽  
Li Zhang ◽  
Xijian Fan ◽  
...  
Keyword(s):  
Linear Regression ◽  
Piecewise Linear ◽  
Piecewise Linear Regression
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