# The Impact of Effective Microorganisms on Flesh Color and Chemical Composition of Raw Potato Tubers
## 4 Discussion
EMs allowed the cultivars to maintain vegetation longer and extend the harvesting period, especially the accumulation period for dry matter and starch. According to [PERSON] and [PERSON] [19], using a 10% EM solution for seed treatment reduces the index of stem base infection pathogenic fungi of the genus _Septoria_ sp., _Fusarium_ sp., _Botrytis_ sp., and _Alternaria_ sp. The reduction of potato diseases under the influence of EMs was also observed by [PERSON] [48] and [PERSON] and [PERSON] [21]. However, the mechanism of this action is unknown, so more research is needed to explain these changes. The color of the flesh tubers depended significantly on the cultivation practices used. The greatest saturation of the flesh color of the tuber towards red was observed with the use of fungicides, in the practice of standard cultivation. On the other hand, the highest saturation of the flesh color towards yellow was found in technologies with three or eight applications of biopreparations with EM. No studies directly confirming the influence of EMs on the value of this feature have been found in the available literature. It can only be assumed that EMs induce mechanisms that increase the caroten content in tubers. Their pro-health effect on the human body is known and unlimited. Such properties include, among others, \(\alpha\)-carotene, lutein, canthaxanthin, or zeaxanthin. The most important feature of carotenoids is their antioxidant activity against reactive forms and free radicals. Thanks to this property, carotenoids protect the body against severe chronic diseases [49]. Therefore, it is worth investigating this direction of changes under the influence of EMs. The color of the flesh of potato tubers may be white, cream, yellow, or violet with a whole range of intermediate shades. The yellow color of the flesh is caused by carotenoids (mainly zeaxanthin and lutein) contained in the amounts of a few milligrams per 100 g of tuber [49]. There are also varieties with pink and violet and red-colored flesh due to the presence of anthocyanins in tubers, mainly pelargonidine, petunidin, and malvidin glycosides, in amounts of 2-40 mg/100 g of tuber [50]. The color of the flesh may be adversely affected by the tendency of tubers toward enzymatic darkening [51]. The fungicides used in the research contributed to an increase in total sugars, reducing sugars, and sucrose as well as a significant reduction in the content of dry matter and starch in comparison to the applications with the use of effective microorganisms. These dependencies had a significant impact on the color indexes of the tuber flesh. This is confirmed by the results of studies by [PERSON] and [PERSON] [51]. The research of [PERSON] [48] showed that the use of effective microorganisms in the form of EM Farma Plus, regardless of their form of application, significantly reduces the symptoms of _Ph. infestans_ on potato plants. The influence of varietal characteristics and the soil environment affect the concentration of chlorogenic, citric, and ascorbic acids and iron in potato tubers, which determine the degree of dark color--from gray to black [52; 53; 54; 55; 56; 57]. The research of [PERSON] and [PERSON] [50], [PERSON] and [PERSON] [51], [PERSON] and [PERSON] [55], and [PERSON] et al. [58] proved that the genetic properties of the tested potato cultivars had the greatest impact on the analyzed color traits of raw tuber flesh. Research results also showed that in a year with a large rainfall deficit (2015) and high average air temperatures, significant differences were observed between the cultivars in the brightness of their raw tuber flesh. This shows that varieties react differently to thermal and humidity conditions. It should be assumed that they influence the concentration of chlorogenic, citric, and ascorbic acids and iron in tubers, thus determining the degree of coloration and color saturation of the tuber flesh [55; 58].