Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti The response of Šampion trees growing on different rootstocks to applied organic mulches and mycorrhizal substrate in the orchard Piotr Kiczorowski a , Marek Kopacki b , Bożena Kiczorowska c, ⁎ a Department of Biological Bases of Food and Feed Technologies, University of Life Sciences in Lublin, Głęboka 28, 20-612 Lublin, Poland b Department of Plant Protection, University of Life Sciences in Lublin, Leszczyńskiego Street 7, 20-069 Lublin, Poland c Institute of Animal Nutrition and Bromatology, University of Life Sciences in Lublin, Akademicka Street 13, 20-950 Lublin, Poland ARTICLE INFO Keywords: Šampion Rootstocks Organic mulches Mycorrhizal substrate Minerals ABSTRACT The aim of the study was to evaluate the effects of using organic mulches: barley straw, chipped pine bark, forest humus, compost, cow manure, commercial peat moss, and commercial mycorrhizal substrate on the growth and yield of Šampion apple trees produced on M26, P2, M9, and P22 rootstocks. The investigations were conducted using Šampion apple trees grown on chosen rootstocks and substrates: barley straw, chipped pine bark, forest humus, compost, cow manure, commercial peat moss substrate, and commercial mycorrhizal substrate. Apple trees grown on all analysed rootstocks reached the greatest height on compost and cow manure mulches, and the biggest trunk diameter was achieved by trees growing on the straw mulch. The greatest number (P < 0.05) of fruits was produced by trees growing on the forest humus mulch, especially those grafted on rootstocks M9 and P22. The forest humus, compost, and cow manure mulches had a beneficial effect on the content of mineral elements in the soil and leaves of Šampion trees growing on all rootstocks. The humus, compost, and cow manure mulches had a positive effect on the growth of the apple trees. The organic mulches increased the number apples and the content of minerals in the soil and leaves. 1. Introduction The aim of maintenance of soil fertility is to support its biological balance by systematic application of organic compounds. Humus con- tains the most valuable group of compounds exerting a positive and multidirectional effect on soil properties. Organic matter derived from dead plant and animal remains is valuable in maintenance of microbial life and ensures lumpy texture of soil with improved physical properties (Meyer et al., 2015). Soil humus has buffering properties, which are especially important in conditions of fluctuating or inappropriate pH values. Natural organic mulches are its main sources. They enhance the availability of nutritional and bioactive soil components by increasing the abundance of beneficial soil microbes (Das et al., 2016). Ad- ditionally, various materials of plant origin e.g. straw, leaves, and crop residues increase the aggregate stability and structure of soil and add nutrients and humus to the soil as they decompose, improving its tilth and moisture holding capacity. Stabilisation of soil structure and tem- perature results in reduced evaporative water losses (Shirgure et al., 2003) and can even suppress weed growth (Kaur and Kaundal, 2009; Sharma and Kathiravan, 2009). This can stimulate yields and have a positive effect on the quality and nutritional value of produced fruit (Kiczorowska and Kiczorowski, 2011; Meyer et al., 2015; TerAvest et al., 2011). The type of the rootstocks is a determinant of orchard productivity, as they can change the behaviour of the scion such as vegetative growth, flowering time, and yield. Rootstocks can also exert an effect on many physiological and biochemical parameters in the leaves of the scion (Nadernejad et al., 2013). The mechanisms of arranging the level of vegetative development of the scion by means of the rootstock have not been fully elucidated. In the studies on the dwarfing mechanism, researchers have examined many hypotheses on histological, physio- logical, and biochemical issues (Li et al., 2012). Great importance for achievement of high yields in orchards is attributed to the selection of rootstocks that will be suitable for the soil, orchard model, and culti- vation technology. Therefore, the aim of the study was to evaluate the effects of organic mulches including barley straw, chipped pine bark, forest humus, compost, cow manure, commercial peat moss, and commercial https://doi.org/10.1016/j.scienta.2018.07.003 Received 2 March 2018; Received in revised form 30 June 2018; Accepted 3 July 2018 Abbreviations: BS, barley straw; PB, chipped pine bark; FH, forest humus; CP, compost; CM, cow manure; MS, commercial mycorrhizal substrate; SEM, standard error mean ⁎ Corresponding author. E-mail address: bozena.kiczorowska@up.lublin.pl (B. Kiczorowska). Scientia Horticulturae 241 (2018) 267–274 0304-4238/ © 2018 Elsevier B.V. All rights reserved. T