Variability of Wheat Grain Image and Content of Phenolic Compounds and Carotenoids under the Impact of Selected Novel Plant Protection Treatments

Abstract

Aims: Variability of wheat kernel size and color as well as the content of selected phytochemicals in wheat grain under the impact of selected biological and fungicide crop protection agents was investigated. Study Design: A randomized block method in quadruplicate. Plants sprayed with Sphingomonas sp. bacteria in a tillering phase and during the period of winter wheat heading stage. Place and Duration of Study: Field experiments: Department of Ento and Phytopathology, Tomaszkowo, Poland during vegetation seasons of 2009-10 and 2010-11. Analytical Part: Chair of Food Plant Chemistry and Processing, Olsztyn, Poland Methodology: Wheat plants were protected using Sphingomonas bacteria or Aureobasidium pullulans yeast preparations, or using chemical fungicides and the impact of plant growth promoters was also measured. Image features of kernels were measured using digital image analysis, total contents of grain phenolic compounds, phlobaphenes, flavonoids, proanthocyanidins and carotenoids using spectrophotometric assays, and phenolic acids using high-performance liquid chromatography. Results: Length was the most constant dimension of grain, independent of the type of crop protection, with the coefficient of variation (CV) 0.98%. In contrast, the width varied with CV = 3.13% and thicknesses with CV = 3.53%. The average kernel surface hue (26.44° +/- 0.75) and saturation (27.37% +/- 0.92) values were higher and the intensity of color (61.80% +/- 0.81) was lower than these of cross-section (23.85° +/- 2.12 and 19.06% +/- 1.27, 70.48% +/- 1.64, respectively). Total Folin-Ciocalteu reactive compounds occured in the largest quantities (1045 to 1507 μg g-1). The least variable was content of phenolic acids (CV = 1.13%) and among this group – content of ferulic acid (CV = 0.73%). Conclusion: It was found that the type of crop protection only slightly affected the variability of kernel dimensions and color. Kernels from control (unprotected) wheat plots were smaller and lighter, had less saturated color and were characterized by lower hue values as well as higher total phenolic compounds, and proanthocyanidins content. There were only minor differences between the biological and fungicide crop protection agents used.