Use of the correlation coefficient in agricultural sciences: problems, pitfalls and how to deal with them

Kozak, Marcin; Krzanowski, W. J.; Tartanus, Małgorzata

doi:10.1590/s0001-37652012000400029

Cited by 36 publications

(23 citation statements)

References 34 publications

(26 reference statements)

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“…If the data did not fit this distribution or outliers existed in datasets, the incorrect correlation coefficient could be calculated, causing misleading interpretations. For such skewed data including outliers, the nonparametric measure of association, named Spearman rank correlation, became a more appropriate alternative [52,53]. Before running the correlation analysis, we examined the distribution of all variables from the obtained data through a graphical method, normal quantile plot.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations

Zhou

Lakhssassi

Cullen

et al. 2019

Genes

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Soybean [Glycine max (L.) Merr.] seed is a valuable source of protein and oil worldwide. Traditionally, the natural variations were heavily used in conventional soybean breeding programs to select desired traits. However, traditional plant breeding is encumbered with low frequencies of spontaneous mutations. In mutation breeding, genetic variations from induced mutations provide abundant sources of alterations in important soybean traits; this facilitated the development of soybean germplasm with modified seed composition traits to meet the different needs of end users. In this study, a total of 2366 ‘Forrest’-derived M2 families were developed for both forward and reverse genetic studies. A subset of 881 M3 families was forward genetically screened to measure the contents of protein, oil, carbohydrates, and fatty acids. A total of 14 mutants were identified to have stable seed composition phenotypes observed in both M3 and M4 generations. Correlation analyses have been conducted among ten seed composition traits and compared to a collection of 103 soybean germplasms. Mainly, ethyl methanesulfonate (EMS) mutagenesis had a strong impact on the seed-composition correlation that was observed among the 103 soybean germplasms, which offers multiple benefits for the soybean farmers and industry to breed for desired multiple seed phenotypes.

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Section: Discussionmentioning

confidence: 99%

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations

Zhou

Lakhssassi

Cullen

et al. 2019

Genes

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“…Data of phytotoxicity of maize were correlated to the three foramsulfuron doses in order to asses Pearson's r correlation coefficient (Kozak et al, 2012). Pearson's r correlation coefficient was performed by using EXCEL ® function.…”

Section: Resultsmentioning

confidence: 99%

Optimization of foramsulfuron doses for post-emergence weed control in maize (Zea mays L.)

Pannacci¹

2016

Span J Agric Res

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Four field experiments were carried out from 2011 to 2014 in order to evaluate the effects of foramsulfuron, applied at the recommended (60.8 g a.i./ha) and reduced doses (1/3 and 2/3), on the efficacy against several of the most important weeds in maize. For each “year-weed” combination, dose-response curves were applied to estimate the dose of foramsulfuron required to obtain 90% and 95% weed control (ED90 and ED95). Foramsulfuron phytotoxicity on maize and crop yield were assessed. Foramsulfuron at 1/3 of the recommended dose (20.3 g a.i./ha) provided 95% efficacy against redroot pigweed (Amaranthus retroflexus L.), green foxtail (Setaria viridis (L.) Beauv.), wild mustard (Sinapis arvensis L.) and black nightshade (Solanum nigrum L.). Velvetleaf (Abutilon theophrasti Medik.), common lambsquarters (Chenopodium album L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.) were satisfactorily controlled (95% weed efficacy) with ED95 ranged from 20 to 50 g/ha of foramsulfuron (about from 1/3 to 5/6 of the recommended dose) depending on growth stage. The recommended dose was effective against pale smartweed (Polygonum lapathifolium L.) at 2-4 true leaves (12-14 BBCH scale), but this dose did not kill plants larger than 2-4 true leaves. The ranking among weed species based on their susceptibility to foramsulfuron was: redroot pigweed = green foxtail = wild mustard = black nightshade > velvetleaf = common lambsquarters = barnyardgrass > pale smartweed. Dose of foramsulfuron can be reduced below recommended dose depending on weed species and growth stage. Foramsulfuron showed a good crop selectivity and had no negative effect on maize yield.

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“…However, practice shows that far too often it is misinterpreted or misunderstood (Kozak et al, 2012). Path analysis partitions each individual rY value into a basic direct effect and 11 indirect effects.…”

Section: Paths Of Soil Respiration Causalitymentioning

confidence: 99%

After-effect of long-term soil management on soil respiration and otherqualitative parameters under prolonged dry soil conditions

Feizienė¹,

Janušauskaitė²,

Feiza³

et al. 2015

Turk J Agric For

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°C is 2718 °C and the growing period lasts only 195 days. However, during the last decades, air temperature exceeding 25 °C has been registered 12 and 25 times per year at the Baltic Sea coast and in the continental part, respectively (Bukantis et al., 2000;Bukantis and Valiuškevičienė, 2005). According to the HELCOM assessment, hot days will become more frequent and severe Abstract: Climatic conditions of environmental zone Nemoral 2 of Europe are favorable for agricultural development. However, more frequent events of hot air-waves and prolonged droughts occurring as a consequence of climate change lead to soil moisture content reduction down to the plant wilting point. Dry soil conditions may have negative consequences for soil as a habitat. The goal of this study was to evaluate the cumulative after-effect of long-term conventional (CT) and no-tillage (NT) application in combination with or without crop residues on soil physicochemical properties, microbiological activity, and soil respiration (SR) under prolonged dry soil conditions. Long-term CT with residue returning created a soil environment that was more resistant to dry conditions than NT. Longterm CT with residue returning created a qualitative soil environment in which the main direct determinants for SR were fungal (F) and bacterial (B) community and carbon/nitrogen ratio (C/N). Slightly weaker contributors for SR were available phosphorus (PAL), plant wilting point (PWP), plant available water (PAW), and urease activity (UR); however, they acted as indirect factors. Long-term spreading of residues on soil surface under NT determined the decrease in water capacity in mesopores and micropores. Significant reduction in field capacity and PWP was revealed, while PAW remained unchanged compared to NT with residues removed. Main direct determinants for SR were F and PAL. Slightly weaker indirect contributors for SR were B, dehydrogenase, UR, and PAW.

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Use of the correlation coefficient in agricultural sciences: problems, pitfalls and how to deal with them

Cited by 36 publications

References 34 publications

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations

Optimization of foramsulfuron doses for post-emergence weed control in maize (Zea mays L.)

After-effect of long-term soil management on soil respiration and otherqualitative parameters under prolonged dry soil conditions

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