Effect of biostimulant application and long-term storage on the nutritional value of carrot

Abstract

The nutritional value of carrot is determined by the content of total sugars and monosaccharides, carotenoids and vitamins, including vitamin C, in its roots. In 2009-2011, field experiments were carried out concerning the effect of biostimulating preparations applied during the carrot vegetation period on selected nutrients of its roots (total sugars, monosaccharides, carotenoids and vitamin C). Two biostimulants were foliarly applied in doses of 2 or 3 L ha-1 on various dates. Kelpak SL and Asahi SL: one, two or three applications; where, second and third applied at 2-week interval, additionally Kelpak SL: one application at 4-leaf phase, followed by additional application after 4 weeks. The field study was conducted in a randomized block design with four replications. The treatments of plant protection from diseases and pests complied with carrot requirements. The subject of the research was carrot of the Karotan cultivar. The content of selected components in carrot roots was determined directly after harvest and after six months of storage in the storage chamber with controlled temperature and relative air humidity. The foliar application of Kelpak SL in a single dose (2 L ha-1) at 4-leaf development phase resulted in the significant increase of total sugars, reducing sugars, total carotenoids and vitamin C. A six-month storage period resulted in a decrease of total sugars by 5% and ascorbic acid by 16.8% compared to nutritional values measured right after harvest.

The Quality of Carrot after Field Biostimulant Application and after Storage

“…The best results in increasing the commercial yield were achieved after the application of Kelpak at doses of 2 or 3 dm 3 ha −1 at the fourth-leaf stage (13.1% and 12.4% respectively, compared to the control). Moreover, the application of biostimulant Kelpak in a dose of 2 dm 3 ha −1 at 4-leaf phase resulted in the significant increase of vitamin C, carotenoids, total sugars, and reducing sugars [24]. In the same treatment, the highest concentration of Mg, P, Na and K in roots has been shown, while the highest content of Ca was after the application of this biostimulant in a dose of 3 dm 3 per ha.…”

“…Recent research involving gene expression analyses is shedding light on plants' metabolic regulatory pathways that are specifically affected by seaweed extracts [18,19]. Their performance is determined not only by weather conditions [13,20,21] but also by the date and the applied dose [20,[22][23][24]. Biostimulants are commonly used in agricultural crops and vegetables.…”

“…They are used for the production of juices, frozen products, dehydrated products and preserved carrots [25][26][27]. The quality of carrot roots is determined by numerous factors, including cultivar, environmental conditions, cultivation method and storage technology [24,26,[28][29][30]. The carrot is a vegetable which is very prone to the accumulation of nitrates and nitrites.…”

“…According to the Polish Norms, the content of nitrates in carrot should not exceed 400 mg kg −1 in fresh weight, and in the carrot allocated to processed foods for children below 3 years of age, only 200 mg kg −1 in fresh weight [32]. This is of importance as carrots are a basic component of the diet and the nitrates supplied with vegetables account for 70-90% of the daily amount [24,32,34]. It should also be noted that carrots are an important raw material for many products used in child nutrition.…”

“…Modern technologies of carrot production use a number of agricultural production means supporting yields and quality of crops, including biostimulants. The use of biostimulants in the cultivation of carrots leads to an increase in the produced biomass; however, it can modify the chemical composition of roots [14,23,24,32]. Yet, it is not known whether the use of biostimulators in different doses and dates in field production does not pose a threat to food safety, especially for long-term stored raw materials.…”