ORIGINAL SCIENTIFIC PAPER Influence of plant origin and soil substrate on the behaviour of the MM106 rootstock in stoolbed Agricultural University Plovdiv, 12 Mendeleev Blvd., 4000 Plovdiv, Bulgaria, (e-mail: galysd@abv.bg) Abstract The influence of different soil substrate for culturing and plants with different origin are studied during the stoolbed development process in order to identify the behaviour variations of the apple clonal rootstock MM106. Three types of soil substrate are studied: soil substrate free of woody, soil substrate with small of woody (1-2 mm) and soil substrate with large of woody (8-10 mm).đ The origin of the studied plants comes from roots adventive buds, clonal micro propagation and from leaf explants. Best growth indicators values are found on plants derived from leaf explants developed in soil with woody with size of 1-2 mm. Key words: apples clonal rootstocks, MM106, propagation, stoolbed, woody Introduction The most widely used apple clonal rootstocks propagation method is the vegetative one. The most applied one is through covering of the vertical shoot originating from the adventive buds of the roots in a stoolbed (Trachev, 1973). The goal of the nursery men is to increase the productivity of first-class root shoots of apple rootstocks. This is the reason why more effective propagation systems are developed. Several decades ago the in vitro propagation technique became popular in apple rootstocks production. There are different methods of micro propagation and the most widely applied method is the clonal one (Ivanova, 1988). Recently, not only in the experimental field (Dobrevska, 2008), but also in practice (Dobrevska, 2011, 2013), somatic organogenesis from leaf implants has been used in the production of apple clonal rootstocks. Different studies over the years have contributed to better understanding the method of rootstocks production in stoolbed through the traditional method of covering (Trachev, 1973; Trachev et al., 1975; Gryazev, 1979; Koval, 1980; Verobyov, 1985; Karpenchuk, 1993; Pepelyankov and Dobrevska, 1995; Dobrevska and Tabakov, 2002; Lipa and Lipicki, 2006; Dobrevska, 2010; Lipa, 2012). Later, the experimental work for obtaining of apple rootstocks through clonal micro propagation began (Ivanova, 1988; Webster and Jones, 1989; Quamme and Hogue, 1994). The new technology of apple rootstocks micro propagation through somatic organogenesis of leaf implants is still not widely used in practice. Dobrevska (2008, 2011) develops a technology for micro propagation of apple rootstocks M9 and MM106 from leaf explants and investigates some growth specifics of apple clonal rootstock M9 obtained through the somatic organogenesis method in stoolbed. The good root development of the shoots is mainly determined by the contents of the covering soil substrate. The change in the soil indicators, when using organic particles from woody fillings, has a beneficial effect for the plants development (Stamatov et al., 1982; Stojanowska, 1987; Szewczuk, 2000; Licznar and Licznar, 2004). Proceedings.. Opatija. Croatia (570 574) 570
Influence of plant origin and soil substrate on the behaviour of the MM106 rootstock in stoolbed There is no previous research which investigates the role of the soil substrate and the origin of the initial plants for creating a stoolbed. Therefore, the above mentioned two aspects- the different origin of plant when creating a stoolbed plant and the contents of the covering soil layer- are the main subjects of the current study. Materials and methods The studied plants were monitored in the period between 2011 and 2013 at the experimental field of the Fruitgrowing department of the Agricultural University- Plovdiv which is located in the Brestnik village area, near Plovdiv. The initial plants, which participated in the creation of the stoolbed plant, were developed based on classic technology of clonal micro propagation (Ivanov, 1988), as a result of somatic organogenesis of leaf explants (Dobrevska, 2008) and following the traditional approach through clonal shoots from adventive buds (Mitov et al., 1996). The covering soil layer at the stoolbed was enriched with: 1. small of woody (1-2 mm in size); 2. large of woody (8-10 mm in size); 3. no additions of woody to the soil. According to Pepelyankov et al. (1998), the soil in the stoolbed is Chromic cambisols. The Fisher s block method was applied when launching the experiment (Zapryanov and Marinkov, 1978). The reported results after recording the growth indicators (average number of shoots per plant, average length of shoots, average length of feathers, average number of feathers per shoots, average thickness of shoots, average number of roots per shoots, average number of nodes per shoots, average length of internodes and leaf area) were analysed using the ANOVA (analysis of variance) with Duncan post hoc test. Results and discussion When analysing the average number of shoots per plant, the highest results are obtained from the soil combination with small of woody (Table 1). When the plant origin is taken into account, the plants produced through somatic organogenesis show the highest results and those produced through adventive buds show the lowest ones. Table 1 of shoots per plant, average length of shoots and average number of roots per shoots of shoots per plant Average length of shoots, cm of roots per shoots Indicator Composition of soil substrate Composition of soil substrate Composition of soil substrate Adventivebuds 17.7 18.7 a 15.0 51.8 59.4 a 55.7 ab 24.5 24.7 a 19.7 Clonal micropropag. 29.0 26.7 21.7 64.8 63.0 64.2 a 31.4 39.5 a 31.3 Somatic organogenesis 33.7 34.3 a 28.3 67.2 74.1 a 66.2 b 30.5 42.7 a 39.5 Signif. at 5 %(a) 32.0 11.1 14.7 19.4 14.6 6.2 10.5 12.0 24.7 1 %(b) 53.0 18.3 24.4 32.3 24.3 10.3 17.4 20.0 41.0 0.1 %(c) 99.1 34.3 45.7 60.3 45.4 19.2 32.5 37.3 76.7 In accordance to the second indicator- average length of shoots (table 1), the plants produced from leaf explants cultivated in soil substrate with small of woody demonstrate the highest number of root shoots. Once again, the same tendency for better results like in the first indicator is repeated. Besides, there are statistically significant differences with all shoots from the soil substrate with no woody The number of feathers, which increase the over ground vegetative mass, unambiguously demonstrate the improved development of the rootstocks. In our experiment, the differences in all combinations are with Section 9. Pomology 571
strong and very strong statistical significance; the highest number of feathers is shown in plants with somatic organogenesis origin cultivated in soil with small of woody, whereas the smallest number of feathers is related to the plants with adventive buds origin (table 2). Table 2 Average length of feathers, average number of feathers per shoots and average thickness of shoots Average length of feathers, cm of feathers per shoots Average thickness of shoots, mm Indicator Composition of soil substrate Composition of soil substrate Composition of soil substrate Adventive buds 4.2 6.7 4.4 6.1 ac 6.0 bc 5.0 c 8.2 8.2 a 8.2 Clonal micropropag. 5.0 7.4 5.6 6.2 ac 6.5 b 5.2 c 8.8 8.9 a 8.8 Somatic organogenesis 5.0 7.4 5.6 7.1 c 7.1 bc 6.1 c 8.9 9.0 a 8.9 Signif. at 5 %(a) 14.4 11.9 7.1 0.1 0.3 0.3 2.3 0.7 1.0 1 %(b) 23.8 19.7 11.8 0.2 0.5 0.5 3.7 1.1 1.7 0.1 %(c) 44.5 36.9 22.0 0.3 1.0 0.9 7.0 2.1 3.1 In respect to the length of the feathers, there are no statistically significant differences among the different combinations (table 2). The thickest but still with first-class quality standard are the shoots with somatic organogenesis origin cultivated in soil with small s of woody (table 2). This development is perhaps due to the higher number of feathers on them which increases the vegetative green over ground mass resulting in stimulated photosynthesis of this combination. An important indicator which determines the quality of the rootstocks produced in stoolbed is their roothold. The reported data in relation to this indicator are shown in table 1. The plants with somatic organogenesis origin cultivated in soil with small s of woody demonstrate the best results. These outcomes are perhaps driven not only from the added organic content in the soul which coincides with the results from the previous study in the Plovdiv area, but also due to the different origin of the initial plants used in the stoolbed creation process (Dobrevska, 2013). Table 3 of nodes per shoots and leaf area of nodes per shoots Leaf area, cm 2 Indicator Composition of soil substrate Composition of soil substrate Adventive buds 34.0 55.0 38.3 17.0 a 15.0 a 14.1 Clonal micropropagation 31.7 33.8 41.3 14.3 11.7 a 13.0 Somatic organogenesis 35.4 38.0 36.5 14.2 a 13.2 14.3 Signif. at 5 %(a) 11.3 24.4 6.1 2.8 3.3 3.0 1 %(b) 18.7 40.5 10.2 4.1 5.3 4.5 0.1 %(c) 34.9 75.6 19.0 6.6 8.5 7.3 The number of nodes of the different combinations do not differ significantly (table 3). When analysing the average length of internodes (table 4) - an indicator which determines the grafting quality- the best results are demonstrated by the combinations with micro propagation origin. The somatic organogenesis leads with 1.9, followed by clonal micro propagation with 1.8 in soil substrate with organic particles followed by soil without particles. 572
Influence of plant origin and soil substrate on the behaviour of the MM106 rootstock in stoolbed Table 4 Average length of internode, cm With a large Contents of the soil substrate With a small Free from woody Average origin Adventive buds 1.5 1.1 1.5 1.4 Clonal micropropagation 2.1 1.9 1.6 1.8 Somatic organogenesis 1.9 2.0 1.8 1.9 Average composition of soil substrate 1.8 1.6 1.6 Undoubtedly, the most important physiological process dependent on many factors and determining the good plant development is the photosynthesis. The photosynthesis efficacy depends on the average leaf area of the leathers. In the current experiment, the leaf areas of some plants with small and large s of woody demonstrate statistically significant differences (table 3). In relation to this, the plants with somatic organogenesis origin cultivated in soil with small s of woody develop better root shoots. This is partially due to the larger leaf aggregate, which when presented in plants with a higher number of feathers (as it is in this case), result in larger total leaf area (Dobrevska, 2013). Conclusions In this experiment, the following conclusions can be drawn: Better first-class root shoots are developed in the stoolbed plants with somatic organogenesis origin cultivated in soil with organic particles of woody with 1-2 mm in size. Because of these results, we can recommend the usage of small s of woody as an addition of the covering soil layer in the apple clonal rootstock MM106 in stoolbed combined with the plant origin- somatic organogenesis from leaf explants. This method makes the production process more expensive but the extra cost is fully compensated by the higher production of first-class rootstocks. References Dobrevska G. (2008). Effects of adventitious organogenesis on phenotypic and genetic manifestations of apple clonal rootstocks M9 and MM106. Dissertation. Plovdiv. Dobrevska G. (2010). Characteristics of some apple rootstocks in relation to the intensification of production. Agricultural Sciences. 3:5-10. Agricultural University Plovdiv Dobrevska G. (2011). Behavior of apple rootstock M9 produced somatic organogenesis in stoolbed, Agricultural Science and Technology. 3 (3):261-264. St. Zagora Dobrevska G. (2013). Apple clonal rootstocks. Plovdiv Dobrevska G., S. Tabakov (2002). Study of apple clonal rootstocks in a stoolbed. Collection Scientific conference with international participation. II:259-262. St. Zagora 2002 Gryazev V. A. (1979). Productivity vegetatively propagated rootstocks in stoolbed at various planting patterns. Collection of scientific papers of VNNI Horticulture Ivanova К. (1988). Opportunities to increase of propagating coefficient in vitro propagation of apple rootstocks, Dissertation. Plovdiv Karpenchuk G., V. Zamorsky, Y. Artemenko (1993). Root distribution of clonal rootstocks of apple trees in the stoolbed and in the orchard. Journal of Fruit and Ornamental Plant Research. 1(3):75-83 Koval A. T. (1980). Productivity of intensity stoolbed of clonal rootstocks of apple., Viticulture and winemaking of Moldavia. 12:61-65 Licznar M., S. E. Licznar (2004). Influence of 10-years mulching with different materials in the rows on some properties of soil, growth and yielding of apple trees Elstar cv. Roczniki Gleboznawcze, 55(1):153-160 Lipa T. (2012). Growth, quality and productivity in stool beds of rootstocks M.9 and M.26. Electronic Journal of Polish Agricultural Universities, 15(1):87-81 Section 9. Pomology 573
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