GF677 Rootstock Research Articles

Effect of Boron Application on Yield, Quality, and Nutritional Status of Peach Cultivar Andross

During the cultivation period of 2005–2007, a project was carried out in the region of Eirinoupolis, prefecture of Imathia, Macedonia, northern Greece. The study investigated the application of boron (B) timing (flowering, fruit set, fruit growth) and method (soil and foliage) on the vegetative growth, fruit yield and quality, and nutritional status of the cling-stone peach variety Andross. The cultivar was grafted onto an 8-year-old rootstock GF 677. The results showed that the greatest marketable yield (135 kg tree–1) was achieved in peach trees where B was applied on soil during the flowering stage in combination with a balanced nitrogen–phosphorus–potassium (NPK) basal application. Boron concentration in fruits of that treatment was increased in both cultivation years compared to most of the applied treatments. Foliar application of B at flowering, fruit set, and fruit growth, primarily in combination with foliar calcium (Ca) application, showed fruits to be less affected by cracking and Monilinia over all treatments. However, foliar application of Ca did not significantly promote leaf or fruit Ca concentration.

CHANGES IN QUALITY PARAMETERS DURING FRUIT DEVELOPMENT AND THEIR RELATIONSHIP WITH OPTIMUM HARVEST MATURITY FOR 'BIG TOP' AND 'PERFECT DELIGHT' NECTARINE CULTIVARS

ISHS VI International Postharvest Symposium CHANGES IN QUALITY PARAMETERS DURING FRUIT DEVELOPMENT AND THEIR RELATIONSHIP WITH OPTIMUM HARVEST MATURITY FOR 'BIG TOP' AND 'PERFECT DELIGHT' NECTARINE CULTIVARS

Metabolic response in roots of Prunus rootstocks submitted to iron chlorosis

Iron deficiency induces several responses to iron shortage in plants. Metabolic changes occur to sustain the increased iron uptake capacity of Fe-deficient plants. We evaluated the metabolic changes of three Prunus rootstocks submitted to iron chlorosis and their different responses for tolerance using measurements of metabolites and enzymatic activities. The more tolerant rootstocks Adesoto ( Prunus insititia) and GF 677 ( Prunus amygdalus × Prunus persica), and the more sensitive Barrier ( P. persica × Prunus davidiana) were grown hydroponically in iron-sufficient and -deficient conditions over two weeks. Sugar, organic and amino acid concentrations of root tips were determined after two weeks of iron shortage by proton nuclear magnetic resonance spectroscopy of extracts. Complementary analyses of organic acids were performed by liquid chromatography coupled to mass spectrometry. The major soluble sugars found were glucose and sucrose. The major organic acids were malic and citric acids, and the major amino acid was asparagine. Iron deficiency increased root sucrose, total organic and amino acid concentrations and phospho enolpyruvate carboxylase activity. After two weeks of iron deficiency, the malic, citric and succinic acid concentrations increased in the three rootstocks, although no significant differences were found among genotypes with different tolerance to iron chlorosis. The tolerant rootstock Adesoto showed higher total organic and amino acid concentrations. In contrast, the susceptible rootstock Barrier showed lower total amino acid concentration and phospho enolpyruvate carboxylase activity values. These results suggest that the induction of this enzyme activity under iron deficiency, as previously shown in herbaceous plants, indicates the tolerance level of rootstocks to iron chlorosis. The analysis of other metabolic parameters, such as organic and amino acid concentrations, provides complementary information for selection of genotypes tolerant to iron chlorosis.

Establishing maximum daily trunk shrinkage and midday stem water potential reference equations for irrigation scheduling of early maturing peach trees

Measurements of midday stem water potential (Ψstem) and maximum daily trunk shrinkage (MDS) were taken over a 4-year period in early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar) grafted on GF-677 rootstock. Plants were irrigated daily above their water requirements in order to obtain non-limiting soil water conditions. The results indicated that seasonal reference equations can be obtained for MDS and Ψstem using crop reference evapotranspiration (ETo), daily mean vapour pressure deficit (VPDm) and mean daily air temperature (Tm) in the case of MDS, and ETo and VPDm in the case of Ψstem. In this way, VPDm was seen to be the best predictor of MDS and Ψstem, without both were influenced significantly by yield or crop load variations between years. When the postharvest regression between MDS or Ψstem and the meteorological parameters mentioned were broken down into early and late postharvest periods, the correlation coefficients improved and were closely related to the presence or absence of sugar-demanding sinks, such as active root growth. A negative linear relationship between MDS and Ψstem was found, pointing to unchanging radial hydraulic conductivity in the bark tissues and suggesting that MDS depends to a great extent of the water potential.

EARLY PERFORMANCE OF TWO EUROPEAN PLUM CULTIVARS ON THIRTEEN PLUM ROOTSTOCKS

The nursery and field performance of the rootstocks GF 655-2, Ishtara ® Ferciana, Jaspi ® Fereley, Jutior ® Ferdor, Marianna GF 8.1, Myrari ® Yumir, Myrobalan B, Myrobalan P 1254, Myrocal ® Fercino, Plumina ® Ferlenain, St Julien Hybrid No. 2 and Torniel ® Avifel and the standard rootstock 'St. Julien Wangenheim' were investigated during the years 2001-07. All rootstocks were budded with the plum cultivars 'Kirke', 'Ive' and 'Opal' and compared during the first six years after planting. The average bud take was 35%. The highest bud take for 'Kirke' was in combination with the rootstock 'St. Julien Wangenheim' with 75%. The highest bud take with 'Ive' was in the combination with Jaspi ® Fereley with 52%. The combination of 'Opal' on the rootstock 'St. Julien Hybrid No. 2' had an 80% bud take. The most vigorous rootstocks were Myrocal ® Fercino, Myrobalan P 1254 and Marianna GF 8.1, which on average increased the trunk diameter by 94.6, 93.6 and 84.9 mm, respectively, during the six years in the orchard. The rootstocks with the largest yield efficiency calculated as accumulated yield 2004-07 per cm 2 trunk cross section area were GF 655-2 with the plum 'Ive' and Jaspi Fereley with the plum 'Kirke'. Fruits of 'Kirke' on the rootstock Plumina ® Ferlenain matured and ripened 5 days earlier than any other rootstock combinations with 'Kirke' scions. The combination of 'Kirke' and the rootstock Jaspi ® Fereley each year resulted in a large crop and gave the largest accumulated yield at 25.6 kg/tree, in the years 2004-07. Four of the well producing rootstock combinations with 'Kirke' also produced the largest fruit. The significantly largest fruits came from the combination of 'Kirke' and Ishtara ® Ferciana at 50.4 g. The largest accumulated yield of 'Ive' was in combination with the rootstock GF 655-2 at 60.9 kg per tree. Of the thirteen rootstocks tested we conclude that none were truly dwarfing. The best growth control was provided by Ishtara ® Ferciana and GF 655-2. Ishtara ® Ferciana contributed to the production of large fruits for both 'Kirke' and 'Ive'. The most productive rootstocks were Jaspi ® Fereley with 'Kirke' and GF 655-2 with 'Ive'.

EVALUATION OF VIGOROUS AND DWARF PLUM ROOTSTOCKS IN THE HIGH DENSITY ORCHARD IN CENTRAL POLAND

The influence of two seedling rootstocks originated from Prunus cerasifera var. divaricata Borkh. and 'Wangenheim Prune' (P. domestica L.) as well as four clonal rootstocks (GF 655/2, 'Jaspi', 'Ishtara', St. Julien A) on the tree growth, yield and fruit weight of 'Hanita' and 'Dabrowice Prune' plum cultivars was investigated in 2000-2007. Results obtained showed that these rootstocks modified the growth intensity of trees of both investigated plum cultivars. The trees grafted on 'Ishtara' rootstock were the most vigorous in this experiment. The least growth was on trees grafted on 'Wangenheim Prune' seedlings. Trees grafted on 'Ishtara' rootstock had a significantly higher cumulative yield per tree than those on other evaluated rootstocks. It was also proved that rootstocks had an influence on the fruit weight of both cultivars. Generally, the fruits harvested from trees grafted on Wangenheim Prune seedlings had the smallest weight. The fruit weight of trees on 'Ishtara' rootstock was the largest. Health status examination of trees of both cultivars showed that some trees grafted on 'Jaspi' rootstocks were not winter hardy enough in Polish weather conditions. As a result of this many trees grafted on this rootstock were firstly attacked by fungal diseases (Leucostoma cinta Hohn., Valsa malicola Urban.) and then they died. Taking into consideration features such as the quantity and quality of fruit crop, results from the experiment with high density planting of trees showed that plum rootstocks GF 655/2, 'Ishtara' and ST. Julien A performed well in Polish climatic conditions. In contrast, plum trees grafted on 'Wangenheim Prune', a dwarfing rootstock, require fertile soil, no specific replanting problems and appropriate high mineral fertilization.

COPPER EFFECTS ON PRUNUS PERSICA IN TWO DIFFERENT GRAFTING COMBINATIONS (P. PERSICA × P. AMYGDALUS AND P. CERASIFERA)

Growth, chlorophyll content, biomass dry weight (DW), nutrient uptake and copper (Cu) accumulation were evaluated in BigTop® peach (Prunus persica L. Batsch) grafted onto two different rootstocks [GF677 (P. persica × P. amygdalus) and Mr.S2/5 (P. cerasifera)] when grown in the presence of 0.1, 10 or 100 μM copper sulfate (CuSO4). Although scion shoot length varied significantly in response to Cu concentration only with Mr.S2/5 rootstock (40%reduction at 100 μM Cu compared with control), Cu concentration in the scion grafted on GF677 was higher (18.2 mg kg−1) compared to that grafted on Mr.S2/5 (10.5 mg kg−1). In both graft combinations, the Cu concentrations in leaves were not statistically different although values ranged between 4.7 and 8.1 mg kg−1. The DW of leaves and stems was not statistically different from control plants in both graft combinations. On the contrary, root DW of Mr.S2/5 increased, about 13% at 10 μM Cu and 43% at 100 μM Cu. In contrast, DW of GF677 roots at higher Cu treatment was significant lower than control. Chlorophyll reduction Cu induced was not found, suggesting that the degradation of these pigments is maintained at low levels. The uptake of sodium (Na), zinc (Zn), and iron (Fe) changed during Cu stress. The different behavior observed between GF677 and Mr.S2/5 regarding Cu accumulation proves that these two rootstocks have a different ability in translocation and accumulation of Cu in presence of this heavy metal. The use of GF677 rootstocks, in substrates particularly rich of Cu, insures a better development of scion growth when compared to Mr.S2/5, but determines a higher Cu concentration in the stem, while Mr.S2/5 seems to be able to stabilize the Cu concentrations in the scion.

Soil fungal communities as indicators for replanting new peach orchards in intensively cultivated areas

Italy and Spain are Europe's main peach-producing countries. Since the mid-90s, however, peach-growing areas have decreased in Italy thus causing its loss of European leadership. One of the reasons for the decline is the presence of replant disorders in peach orchards. As soil-borne pathogens are one of the biotic components of aetiology, a study was performed in an intensively cultivated area of southern Italy, to investigate the use of soil fungi as indicators of soil health when planting new peach orchards. Soil sampling was carried out in five replanted peach orchards and five horticultural sites in the “Piana del Sele”, a peach and vegetable-growing valley in the Campania region. Three different soil fungi communities were recorded: soil-inhabiting filamentous fungi; endophytic root fungi, based on cultural methods; and uncultured soil fungi, based on nucleotide sequences of internal transcribed spacers (ITS1 and ITS2) and rDNA gene fragments. Soil health was evaluated with a greenhouse bioassay, using young plants of peach rootstock GF677. Diversity and composition of fungal communities were compared using PAST, a software which includes several functions commonly used in paleoecology. Each peach tree orchard was characterized by a significantly higher diversity score than horticultural crops. The two cultivation systems differed widely for species composition suggesting that vegetative cover and cultivation practices strongly affected fungal community composition. The bioassay to evaluate soil health showed a significant growth reduction in horticultural sites compared to peach sites. This finding was supported by the high abundance of Cylindrocarpon destructans and Thielviopsis basicola, two aggressive root rot agents, within endophytic fungal communities in horticultural sites. In this survey, greatest fungal diversity corresponds to best plant growth. From a practical point of view, when deciding to replant a new fruit tree orchards in intensively cultivated areas, a greenhouse bioassay with the target crop, combined with a quantitative analysis of endophytic root fungal communities, may help in deciding the best soil use.

EFFICACY OF HJB/FE3+ TO PROVIDE FE TO NECTARINE PLANTS IN CALCAREOUS SOILS

Iron (Fe) chlorosis is a widespread problem in fruit crops grown on calcareous soils. To date, the application of synthetic Fe chelates is the most effective solution to correct this problem. The aim of this work was to study the effectiveness of a new synthetic Fe chelate, HJB (N,N'-Bis(2-hydroxy-5-methylbenzyl) ethylenediamine-N,N'-diacetic acid), in providing Fe to nectarine trees grown under alkaline field conditions. HJB has a similar structure as o,oEDDHA but its synthesis may produce purer commercial products than the EDDHA process that produces o,oEDDHA combined with a mixture of regioisomers (o,pEDDHA and p,pEDDHA) and other unknown by-products. The experiment started in 2007. Nine-year-old nectarine cultivar 'Zephyr' trees (Prunus persica L. Batsch) grafted in GF677 rootstocks were used. Two treatments with two different doses (0.45 g Fe-chelate/tree and 0.90 g Fe-chelate/tree) were evaluated: a commercial EDDHA/Fe 3+ product (5.19% Fe chelated by o,oEDDHA), HJB/Fe 3+ (7.97% Fe chelated by HJB) and an untreated (-Fe) control. The Fe compounds of the +Fe treatments were apportioned into three unequal doses that were directly injected into the soil three times during the growing season. SPAD index values were measured every two weeks and leaves were sampled 36, 58, and 91 days after the first application of the +Fe treatments. Yield, fruit weight, number of fruits per tree, and fruit diameter were also determined. In the first year, HJB/Fe 3+ and EDDHA/Fe 3+ improved SPAD values compared to the -Fe control; however, no significant differences were found with respect to leaf Fe concentration or fruit yield of the +Fe treated and -Fe control trees. Currently, a second year of experimentation is being developed.

Evidence of pAgK84 transfer from Agrobacterium rhizogenes K84 to natural pathogenic Agrobacterium spp. in an Italian peach nursery

Nine Italian peach nurseries, which use Agrobacterium rhizogenes strain K84 to protect plants from crown gall, were monitored for three years with the aim of determining whether transconjugant populations may arise following plasmid exchanges between K84 and autochtonous soil agrobacteria. Six hundred and seventy‐eight Agrobacterium isolates were obtained from 120 tumours developed on apricot and peach rootstocks that had been treated in pre‐planting with the antagonist. Agrobacteria were characterized for pathogenicity, biovar, opine catabolism and agrocin 84 sensitivity. Colony hybridization was used for screening the isolates harbouring plasmids pTi and/or pAgK84. Analysis of plasmid content and Southern blotting were performed on putative transconjugant agrobacteria found in tumours collected from one nursery where a biological control breakdown was observed. The RFLP analysis of 16S + IGS regions showed that pAgK84 was transferred from the antagonist to virulent and avirulent soil agrobacteria belonging to different ribotypes. Pathogenic transconjugants, inoculated on GF677 rootstocks, were not controlled in vivo by K84 and stably maintained pTi and pAgK84 in the bacterial cells for at least one year. At the end of a biocontrol trial, new transconjugant tumorigenic agrobacteria originated by the transfer of pAgK84 to the pathogen. Virulent and avirulent transconjugants may represent a real threat for biological control by K84 strain since all of them produced agrocin and were insensitive to it. Survival in soil of these populations could make the future application of K84 ineffective.

Elemental 2-D mapping and changes in leaf iron and chlorophyll in response to iron re-supply in iron-deficient GF 677 peach-almond hybrid

Iron is an essential micronutrient for plant growth and development, involved in key cellular processes. However, the distribution of Fe in plant tissues is still not well known. In the so-called Fe chlorosis paradox, leaves of fruit trees grown in the field usually have high concentrations of Fe but still are Fe-deficient. Leaves of the Prunus rootstock GF 677 (P. dulcis × P. persica) grown in hydroponics have been used to carry out two-dimensional (2-D) nutrient mapping by synchrotron radiation-induced X-ray fluorescence. Iron-deficient leaves accumulated more Fe in the midrib and veins, with Fe concentration being markedly lower in mesophyll leaf areas. The effects of Fe deficiency and Fe re-supply on leaf chlorophyll concentration and on the distribution of Fe and other nutrients within different plant tissues have been investigated in the same plants. After Fe re-supply, leaf Fe concentrations increased largely in all leaf types. However, whereas re-greening was almost completely achieved in apical leaves, in some expanded leaves the increase in chlorophyll concentration was only moderate. Therefore, after Fe re-supply Fe-deficient expanded leaves of the Prunus rootstock GF 677 had significant increases in Fe concentration but were still chlorotic. This is similar to what occurs in leaves of peach trees in field conditions, opening the possibility that this system could be used as a model to study the Fe chlorosis paradox.

INFLUENCE OF ARBUSCULAR MYCORRHYZAL FUNGI ON FRUIT ROOTSTOCKS

ISHS XXVII International Horticultural Congress - IHC2006: International Symposium on Sustainability through Integrated and Organic Horticulture INFLUENCE OF ARBUSCULAR MYCORRHYZAL FUNGI ON FRUIT ROOTSTOCKS

The effect of Fe-EDDHA and of ascorbic acid on in vitro rooting of the peach rootstock GF-677 explants

The objective of this research was to study the effect of the chelated form of the iron salt of ethylenediamine di-o-hydroxyphenylacetic acid (Fe-EDDHA) (6% Fe) on in vitro rooting of the rootstock GF-677. The iron salt of ethylenediamine tetraacetic acid (Fe-EDTA) (12% Fe) of the MS basic medium was replaced by Fe-EDDHA, which was applied in three concentrations: 93.5, 187.0 and 280 mg l−1 (5.6, 11.2 and 16.8 mg l−1 Fe, respectively). For each treatment of Fe-EDDHA, the effect of ascorbic acid added in four concentrations (0, 0.1, 1.0 and 10 mg l−1) was studied. After 4 weeks of culture, the explants growing on the medium with 280 mg l−1 Fe-EDDHA gave the best rooting results. Regarding ascorbic acid, no clear stimulating effect on rooting was found.

GROWTH AND YIELD OF PLUM TREES 'FELSINA', 'TOP' AND 'ELENA' GRAFTED ON 'GF 655/2'

An investigation on the growth and cropping of plum trees, which were cultivated on heavy soil, has been conducted for seven years after planting (1997-2003). The experiment included plum cultivars ‘ Felsina’ , ‘ Elena’ and ‘ Top’ grafted on rootstock GF 655/2, and planted at three densities (3.8 x 1.8, 3.8 x 2.2 and 3.8 x 2.6 m). After 7 seasons, growth of the trees, as indicated by trunk cross-sectional area (TCSA) of ‘ Felsina’ , were the least vigorous while ‘ Top’ were the most vigorous. ‘ Felsina’ did not yield as expected and was very sensitive to plum pox virus. ‘ Top’ and ‘ Elena’ were precocious and produced high yields. ‘ Top’ showed slight sensitivity, whereas ‘ Elena’ was highly tolerant to plum pox virus. In our growing conditions, among cultivars in trial, ‘ Elena’ is the most promising for modern, intensive plum growing because it was precocious, productive and gave fruits of good quality.

Effects of short light-dark regimes on in vitro shoot rooting of some fruit tree rootstocks

Experiments were carried out to evaluate the effects of 4/2 light-dark cycles (4 h of light followed by 2 h of dark) on the rooting responses of shoots cultivated in vitro of the fruit tree rootstocks GF 677 (peach × almond hybrid), Mr.S. 2/5 (Prunus cerasifera), MM 106 (apple Nothern Spy × Paradise M1) and BA 29 (Cydonia oblonga). Under this light regime rooting percentage of GF 677, Mr.S. 2/5 and MM 106 shoots reached 100 % as in the control treatment (16/8), while in BA 29 shoots, short light-dark cycles increased rooting response by about 65 %. Moreover, the shoots of all rootstocks submitted to the 4/2 cycle showed an appreciable increase in root number and length, and an earlier root emergence of about 4 - 5 d compared to the 16/8 cycle. Finally, rooting percentage of BA 29 shoots submitted to the 4/2 light regime and treated with 0.2 mg dm-3 indolebutyric acid (IBA), was equal to that reported with 0.4 mg dm-3 IBA under the 16/8 regime, indicating that the former light regime also amplified the rhizogenic effect of auxin.

The effect of paclobutrazol on in vitro rooting and growth of GF-677 hybrid peach rootstock

This paper deals with the evaluation of the influence of paclobutrazol (N-dimethylaminosuccinamic acid) and 2-naphtoxyacetic acid on rooting and growth of GF-677 hybrid peach rootstocks. The influence of these substances on the average number of roots per plant, the average length of roots per plant and the height of plants was evaluated as well as the effect of the addition of paclobutrazol before and after media sterilisation. As the obtained results indicate, plants, which were rooted on media with paclobutrazol and without auxin had the lowest number of roots per plant. Paclobutrazol showed a statistically significant negative effect on both the length of roots and the height of plants. It canbe concluded that, for the rooting of GF-677 rootstock it is helpful to use auxin plus paclobutrazol in concentration 0.43 µM. Higher concentrations affect inhibition, mainly in height of plants 14 days after transplant to soil.

Studies on the regeneration of peach cultivars and rootstocks from root cuttings in comparison with aerial cuttings

This study showed that shoot cuttings collected from peach trees in February and November gave the highest sprouting percentages. A comparison of 3 cultivars of Prunus persica L. Batch (ArmKing, Early Crest and May Crest) showed that November sampling was optimal for all cultivars. Although the sprouting of root cuttings gave much lower percentages, the peak values occurred at exactly the same times of year as those for root formation. The results also showed that the effectiveness of indole-butyric acid treatment to induce root formation on detached root-shoots was greater when the seasonal rooting level is low. However, this inverse correlation is not significant when all 12 monthly values are combined. The data for comparing the 2 rootstocks and their interaction with the concentration of benzyl-adenine-purine applied showed that St Julien GF655/2 (Prunus insititia) had more productive root-shoots and better growth than Damas GF1869 (Prunus domestica × Prunus spinosa). There was no significant difference between different concentrations of benzyl-adenine-purine, but benzyl-adenine-purine affected the morphology of the young root-shoots. Cold storage for 1 month had a beneficial effect on sprouting of root cuttings of the rootstock GF677 (Prunus persica × Prunus amygdalus) and treatments with bottom heat increased sprouting over that achieved in the growth room. X-ray treated roots produced significantly fewer sprouts.

Influence of Rootstocks, pH, Iron Supply (in Nutrient Solutions) and Agrobacterium radiobacter on Chlorophyll and Iron Concentration in Leaves of a Peach Variety

ABSTRACT In this study, the influence of rootstocks, pH, iron (Fe) supply (in nutrient solutions), and Agrobacterium radiobacter on the leaf chlorophyll and Fe concentration of the peach cultivar ‘Sun Crest’ was investigated. The results showed that chlorophyll index (SPAD-502) and active Fe differed significantly at different pH levels. Chlorophyll index was highest at pH 6.0 and 9.0 and lowest at pH 7.0 and 8.0 Leaf active Fe concentration was highest at pH 6.0 and 7.0 Significant differences between rootstocks and interactions were also found. Chlorophyll index was highest in the leaves of GF677, Antafuel and MRS 2/5, while the leaves of seedling had the lowest chlorophyll index and chlorophyll a and b concentration. The chlorophyll index in the leaves of St. Julien 655/2 did not differ from those of MRS 2/5. However, seedling had the highest leaf active Fe concentration. Supply of trees with different Fe levels (in solutions) did not affect positively the leaf chlorophyll index, chlorophyll a and b concentration, or active Fe concentration. The leaf chlorophyll index and active Fe in the rootstocks GF677, Antafuel, and Siberian C were significantly reduced in trees inoculated with Agrobacterium radiobacter.

The rootstock effects on plant adaptability, production, fruit quality, and nutrition in the peach (cv. ‘Suncrest’)

In clayey and calcareous soils without a stable irrigation and fertilization system, the type of rootstock can particularly affect both the vegetative and productive properties of ‘Suncrest’ peach ( Prunus persica L. Batsch) plants, and the qualitative and nutritional attributes of their fruit. The GF677 rootstock ( P. persica × Prunus amygdalus) promoted the highest vegetative development, followed by Julior ( Prunus insistitia). The ‘Suncrest’ on Ishtara [( Prunus cerasifera × P. persica) × ( P. cerasifera × Prunus salicina)] and Barrier1 ( P. persica × Prunus davidiana) had lower, but similar, plant vigour, but the latter rootstock differed in its higher production of pruned wood. The lowest adaptability to these cultivation conditions was observed for ‘Suncrest’ grafted onto Citation ( P. persica × P. salicina), which showed the lowest plant development and production. For the plant yield, the ‘Suncrest’ grafted onto GF677, Julior, Ishtara, and Barrier1 were all similar. The fruit yield and both the canopy volume and pruned wood of ‘Suncrest’ grafted onto Ishtara showed a particular relationship, giving the best indices of yield efficiency and plant physiological equilibrium. Moreover, the same rootstock promoted the largest fruit size, while the smallest fruit were found on GF677 rootstock. The fruit from the Citation ‘Suncrest’ ripened 3 days early, while those from Barrier1 had a late fruit ripening. Firmness, soluble solids and the soluble solids to total acidity ratio were only affected slightly by the different rootstocks, while the total acidity of the fruit varied significantly according to rootstock; the fruit from ‘Suncrest’ grafted onto Barrier1, Julior, and Citation had the highest total acidities. The rootstock effects on the nutritional attributes of the fruit were relevant. The ‘Suncrest’ on Julior and GF677, followed by Ishtara, produced fruit with the greatest antioxidant activities and total phenolic contents. The ‘Suncrest’ on Citation and, especially, Barrier1 had reduced nutritional values of the fruit. The variations in antioxidant activities and total phenolic contents showed a positive correlation.

Effect of Verticillium dahliae, pH, rootstocks and different sources of iron application on the chlorophyll and iron concentration in the leaves of peach trees

The aim of this study was to examine inexpensive techniques to control iron chlorosis. It was found that soil applications with Fe-EDDHA, FeSO4, K2SO4, KNO3, citric acid, Agrobiosol and FeSO4 + cow manure significantly increased the leaf iron concentration 90 days after application. Increased iron concentrations were found only in the leaves of trees supplied with K2SO4 and FeSO4 + 11–15–15, 150 days after application. Foliar applications with Micro-A-Fe, FeSO4, Micro-A-Fe + FeSO4, Mix Fyt + FeSO4, Biomin, Lysodin, FeSO4 + citric acid, FeSO4 + NH2CONH2 + citric acid, FeSO4 + KNO3 + citric acid increased significantly the leaf iron concentration 150 days after application. This study also investigated the effect of pH (in nutrient solution), rootstocks and Verticillium dahliae on iron chlorosis. The response of peach rootstocks was dependent on the pH — the highest iron concentration was found at pH 4 and the lowest at pH 7. Data were also obtained on the susceptibility of the important for the peach industry rootsocks to iron chlorosis. The rootstock St. Julien 655/2 had the highest iron concentration, while no significant differences were found between the rootstocks GF677, MRS 2/5, Seedling and Antafuel the lowest. Verticillium dahliae had no affect on the chlorophyll concentration of peach trees.