Bioactive compounds, total antioxidant capacity and yield of kiwiberry fruit under different nitrogen regimes in field conditions

Abstract

BACKGROUNDActinidia arguta known as the ‘kiwiberry’ or ‘mini kiwi’ is relatively new among the cultivated berry species. Recent studies indicate the kiwiberry fruit could be an important source of many health‐promoting compounds. A knowledge‐based fertilisation concept was evolved to define optimal strategies for feeding Actinidia with nitrogen (N) because a deficit and excess of N both have a negative impact on plants and the surrounding environment.RESULTSKiwiberry yield and fruit internal quality significantly depended on soil N level, cultivar and growing season. A higher soil N led to an increase in carotenoid content and a decrease in phenolic content, whereas ascorbic acid and glutathione contents were not affected by soil N fertility. Under the highest N dose, enzymatic antioxidants were activated. Trolox equivalent antioxidant capacity clearly decreased with an increasing N level.CONCLUSIONSCompetent and skilful fertilisation management should focus on balancing a high fruit yield and maintaining their high quality. Based on yield level and fruit antioxidant potential, the N guide values for A. arguta vary between 30 and 50 mg N per kg−1 of soil. The recommended N dose may depend on overall soil quality traits and cultivar N demand, as well as on weather conditions. © 2020 Society of Chemical Industry

Actinidia arguta Leaf as a Donor of Potentially Healthful Bioactive Compounds: Implications of Cultivar, Time of Sampling and Soil N Level

“…In turn, the glutathione pool was kept at a reduced state, probably due to the stable level of GR activity, which was not influenced by N fertilisation. The recently described kiwiberry fruit total ascorbate and glutathione pools are not dependent on soil N fertility, while enzymatic antioxidants are activated under the highest N dose [12]. As revealed in a previous study based on chlorophyll a fluorescence measurements, 'Weiki' and 'Geneva' express different sensitivities to nitrogen deficiency [43].…”

“…However, because of reduced biomass under N limitations, not all lettuce genotypes exhibited increased antioxidant yields or total antioxidant capacity yield. Therefore, skilful N management should consider the balance between yield and quality [12]. In conclusion, the ascorbate-glutathione cycle could be related to a large number of factors such as species, plant organ and development phase, crop management and weather conditions.…”

“…The accumulation of phenolic compounds in plant tissues is often negatively affected by high N nutrition [12,32,46]. An inverse relationship between N availability and the concentration of phenolic compounds not restricted to a specific developmental stage or cultivation method has recently been reported in the leaves of cereals [32].…”

“…), commonly known as kiwiberry, is a new product on the market that is experiencing growing consumer acceptance as well as an increasing area of production worldwide [10]. Kiwiberry, a fruit with an edible skin, is characterised by high contents of phenolics, carotenoids, vitamin C and thiol compounds [11,12] and it exhibits strong antioxidant activities in DPPH, FRAP and ABTS tests [12][13][14][15]. These fruit traits provide a basis for considering kiwiberry as a health-promoting product (functional food) [14,16].…”

“…In summary, the high quality and functionality of food products, along with sustainable production and possible re-use of by-products, are modern goals of manufacturers and researchers of food products [19,38]. To embrace the concept of sustainability and waste reduction [38], optimal N fertilisation in food production should be targeted in order to reduce soil nitrate losses [12,39].…”