Turkish Journal of Field Crops

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SECOND-ORDER RESPONSE SURFACE METHOD: FACTORIAL EXPERIMENTS AN ALTERNATIVE METHOD IN THE FIELD OF AGRONOMY

Mustafa Agah Tekindal, Hülya Bayrak, Berrin Özkaya, Yasemin Yavuz

Abstract

The main purpose in all experimental designs is to take into account the factors that are considered likely to have an effect on the response variable emphasized, and to minimize the error of experiment in this way. Bread, which is the staple human food, cannot have any negative effect on human beings as long as it is produced by using suitable materials under appropriate conditions. However, when inappropriate amounts of raw materials are used (e.g. non-optimal amounts of bran, yeast or other additives), bread threatens health. In this study, Box-BehnkenDesign (BBD) and Central Composite Design (CCD), the two different designs of the response surface method, were applied to a single dataset. Two designs were evaluated in terms of the results obtained. The purpose in the second-order factorial experiments is to identify the optimum levels of independent variables for the dependent variable. In this study, the implementation of second-order response surface model and interpretation of the results were based on 2 k CCD (Central Composite Design) and BBD (Box-Behnken Design) with one replicate. In the CCD, the amount of bran added, flour type, the ratio of yeast added, furnace temperature, the duration of remaining in the furnace, and fermentation time were accepted to be significant factors that affected volume yield. In addition, R2 = 80.7% shows that the regression equation explains variables by 80.7%. In the BBD, the ratio of bran added, the type of flour, the ratio of yeast added, furnace temperature (only in quadratic form), the duration of remaining in the furnace (only in quadratic form), and fermentation time (only in quadratic form) were accepted to be significant factors that affected volume yield. Furthermore, R2 = 89.64% shows that the regression equation explains variables by %89.64. This method provides savings in terms of time and the amount of material by limiting the area at particular levels. Researcher may use the results of either CCD or BBD (whichever s/he deems suitable) according to the volume s/he wants to obtain.

Keyword: Box-BehnkenDesign, Central Composite Design, Experimental Design, Model, Response Surface Method, Steepest Ascent/Descent ,

Effects of Different Water Stress Levels on Biomass Yield and Agronomic Traits of Switchgrass (Panicum virgatum L.) Varieties under Semi-Arid Conditio

Erdal GONULAL, Suleyman SOYLU, Mehmet SAHIN

Abstract

A field experiment was conducted in the Wielkopolska region at the Gorzyń Research Station, Poland (52.34°N, 15.54°E) in Central Europe. The study was conducted over a 3-year period (2017, 2018, 2019) as a two-factorial design with four replications in the RCBD. The aim of the research was to determine the effect of the cultivar (‘Bolero’, ‘Tytan’) and the inoculation (Nitragina–seeds inoculation, Nitroflora I–seeds inoculation, Nitroflora II–soil inoculation, HiStick® Lupin–seeds inoculation) on plant development, seeds chemical composition and yielding of narrow-leaved lupin. The weather conditions and experimental factors significantly influenced on productivity of narrow-leaved lupin ‘Tytan’. Drought during the growing season reduced seeds and protein yields. After inoculation of HiStck the seeds yield was significantly greater by 12.4% (p < 0.01) and the protein yield after application of Nitroflora I or HiStick by 13.9% (p < 0.01) and 19.2% (p < 0.01), respectively. Correlation coefficients showed strong relations between number of pods and seeds per plant in both cultivars regardless of the inoculation variant, however the strongest relations in both cultivar were proved on HiStick treatment.
Keyword: Biological nitrogen fixation, chemical composition, legumes, protein efficiency, yielding