Quince BA29 Research Articles

Morphological Evaluation of Pear cvs. Santa Maria, Williams, and Deveci Grafted onto Clonal and Seedling Rootstocks

This research was conducted to determine the effects of quince clonal rootstocks [Quince BA29 (BA29) and Quince A (QA)], pear clonal rootstocks [FOX9, FOX11, OHxF333, OHxF87 and FAROLD40] and European pear seedling rootstocks on the morphological characteristics of 'Santa Maria', 'Williams', and 'Deveci' pear cultivars in Bafra (Samsun) ecological conditions in the research years of 2021 and 2022. Morphological characteristics, such as rootstock diameter (mm), trunk diameter (mm), trunk cross-sectional area (cm2), tree height (cm), crown dimensions (width, length, height and volume), leaf stalk length (cm), leaf stalk thickness (mm), leaf dimensions (width, length, area), annual shoot length (cm), node numbers and internode length (cm) were examined in the study. Results of the study revealed significant variation in the case of research years on most morphological attributes; generally, the values were higher in the research year 2022 than in 2021. It has been determined that the effect of rootstocks on all the morphological characteristics was significant except for leaf stalk thickness. The highest morphological values were obtained from OHxF333, FOX11, and FAROLD40 compared to the other rootstocks, and the lowest values were recorded in FOX9, OHxF87, and seedling rootstocks, respectively. Considering the cultivars' effect on the evaluated morphological traits, the highest leaf characteristics, and internode length in the annual shoots were acquired from the 'Santa Maria' cultivar, but all other attributes were higher in the 'Deveci' cultivar. The ' Williams ' cultivar recorded almost all the lowest morphological values. The highest trunk cross-sectional area was determined in the 'Deveci'/OHxF333 (38.63 cm2) and the lowest in the 'Williams'/FOX9 (4.95 cm2). The longest annual shoots were determined in the 'Deveci'/FOX11 (43.05 cm) and the shortest in the 'Williams'/Seedling (16.11 cm). The highest leaf area was observed from the 'Santa Maria'/BA29 (21.11 cm2) and 'Santa Maria'/FOX11 (20.95 cm2) combinations. According to the results of the research, it was determined that OHxF333 rootstock among the evaluated rootstocks performed morphologically better than the others. FOX9 and OHxF87 pear clone rootstocks showed very poor performance compared to other rootstocks.

The overall effect of research years, rootstocks, and cultivars on the morphological attributes of pear trees

This research was conducted to determine the combined effect of 3 factors including rootstocks, cultivars, and research years on the morphological characteristics in Samsun/Türkiye ecological conditions in the research years of 2021 and 2022. Eight rootstocks consisting of quince BA29 (BA29), quince A (QA), FOX9, FOX11, OHxF333, OHxF87, FAROLD40, and European pear seedlings were used in the study, while the cultivars were 'Santa Maria', 'Williams', and 'Deveci'. The study results revealed the significance of the combined factors on all leaf characteristics of European pear. While rootstock diameter, scion diameter, tree length, and trunk cross-sectional area showed insignificant variations. It was determined that the canopy characteristics of ‘Williams' pear cultivar in combination with the FAROLD40 and OHxF333 in the research year 2022 were higher than other combinations, while the same combination was obtained with lower values in the case of other morphological characteristics. Generally, all the morphological attributes were obtained higher in the rootstocks and cultivars combination in the research year of 2022. In conclusion, the genetic capacity of rootstocks, cultivars, and variations of the climate situations in two consequent research years, resulted in variations in the morphological attributes of pear trees.

Determination of Phenological and Morphological Characteristics of Some Standard Pear Cultivars on Different Quince Clonal Rootstocks

This study was conducted to determine the effects of Quince BA29 (BA29), Quince A (QA), and Quince C (MC) rootstocks on phenological and morphological characteristics of ‘Deveci’, ‘Santa Maria’, ‘Abate Fetel’, and ‘Williams’ pear cultivars in Bafra (Samsun) ecological conditions between 2020-2021 years. It has been determined that the effect of rootstocks and cultivars on phenological characteristics was significant. In the study, the earliest flowering and harvest were in ‘Abate Fetel’, the latest flowering was in ‘Williams’, and the latest harvest was in the ‘Deveci’ cultivar. The highest rootstock diameter, trunk diameter and tree height were in BA29 and the lowest in MC rootstock. The highest canopy volume was determined in the ‘Santa Maria’ cultivar and the lowest in the ‘Williams’ cultivar. The effect of rootstocks and cultivars on leaf area was significant and the highest leaf area was determined in ‘Santa Maria’/QA combination. Annual shoot length of the MC rootstock was lower than the other rootstocks. It is thought that it would be more appropriate to continue the research for a long time to determine the most suitable cultivar/rootstock combination as a result of the data obtained due to the young trees of the plants where the research was carried out.

The Effects of Different Rootstocks on the Graft Success and Stion Development of Some Pear Cultivars

ABSTRACT In modern pear growing, quince and pear clonal rootstocks are used instead of pear seedlings. This study aimed to evaluate the effect of different quince and pear rootstocks on the graft success and the stion (scion+rootstock) growth performance of some pear cultivars/genotypes. In the study, quince (Quince BA 29, Quince A and Quince MC), pear (OHxF 333, Fox 11, Farold 40) clones and pear seedlings were grafted in two standard (Deveci and Williams) and 11 local (‘Bardak,’ ‘Dalkıran,’ ‘Eşek,’ ‘İstanbul,’ ‘Kara,’ ‘Karga,’ ‘Karpuz,’ ‘Kış,’ ‘Sarıkum,’ ‘Tefenc’ and ‘Yaz Ziraati’) promising pear cultivars were used. Significant differences were observed in both rootstocks and varieties in terms of graft success and plant development in the study. The graft take, sprout and survival ratios were higher in pear rootstocks than in the quince rootstocks. While the highest graft survival ratio was observed in Fox 11, the lowest was in the BA 29 quince rootstock. The highest graft sprout and graft survival ratio were in ‘Deveci,’ the lowest in ‘Williams,’ ‘Bardak’ and ‘Kış’ varieties. While the highest shoot lengths and highest diameters were detected in the pear seedling, the lowest were in the MC rootstock. While the longest shoots were observed in ‘Kara,’ the thickest shoots were observed in ‘Eşek’ genotypes. As a result of this study, it was determined that the 13 pear cultivars/genotypes grafted on different rootstocks were sufficient in terms of graft success and stion growth performances and it was found that stion of sufficient quality could be grown in the field condition.

Protocol for micropropagation of quince BA29 in semisolid media

Micropropagation is a technique widely known for its ability to produce large numbers of plants in a short period of time. It is essential for breeding programs and to establish micropropagation protocols for economically important species. The aim of this study was to establish a micropropagation protocol for quince BA29, aiming at mass production of plantlets. The explants of quince BA29 were cultured on MS and WPM media (original and 1/2) in combination with BAP (0, 0.5, 1, 2 and 4 mg L-1) for the in vitro multiplication and cultured in MS medium with sucrose (15 and 30 mg.L-1) combined with IBA (0, 0.12, 0.25, 0.50, 1.0 and 2.0 mg L-1) for in vitro rooting. After 45 days, the culture media which provided the best results for growth and multiplication of BA29 explants was the MS original with 2.68 mg L-1 of BAP and the culture media which provided the best results for rooting of BA29 explants was MS with 15 g L-1 of sucrose and 1.25 mg L-1 of IBA.

THE PEAR INDUSTRY IN THE REPUBLIC OF CROATIA

Pear (Pyrus communis L.) is a popular fruit species in Croatia. It is grown mainly on small family farms and less on large plantations. By growing areas, compared to other fruit species, pear is in 9th place, with a share of 3.31% (860 ha out of 26,003 ha). Since the production is less than 10,000 t per year significant quantities of fruit for consumption and processing have to be imported. Based on 15-year data the most common rootstock is Pyrus communis L. (39.1%), followed by Quince BA 29 (25.4%), MC (17.8%), MA (16.4%), Sydo (0.7%) and Adams (0.5%). The most common cultivars is ‘Williams’ (27.3%), followed by ‘Conference’ (16%), ‘Bella di Giugno’ (8.5%), ‘Abbe Fetel’ (7.1%), ‘Butira Precoce Morettini’ (5.5%), ‘Santa Maria’ (5.1%), ‘Poire de Cure’ (4.9%), ‘Beurre Hardy’ (3.5%), ‘Packam’s Triumph’ (2.2%) and ‘Clapp’s Favourite’ (1.9%). The average number of trees per ha is 1,267. Of the total number of registered trees only 9% are grown in the Adriatic Croatia, and the remaining 91% (781.8 ha) in the continental part of Croatia. In the past decade modern plantations have been gradually established on less vigorous rootstocks (mainly MC and less Adams and Sydo) with economically valuable cultivars such as ‘Abbe Fetel’ and ‘Conference’.

The phenolic content and its involvement in the graft incompatibility process of various pear rootstocks (Pyrus communis L.)

This study investigates the influence of various rootstocks for pear on the phytochemical composition in the phloem above and below the graft union and the role of phenols in pear graft incompatibility. Assays of phloem with cambium from 4-year-old 'Conference', 'Abate Fetel' and 'Williams' pear trees grafted on different rootstocks: Quince MA, Quince BA 29, Fox 11, Farold 40 (Daygon), seedling Pyrus communis L. and own rooted (P. communis L.) were analyzed with HPLC-MS. The most abundant phenolic compound in phloem above and below the graft union was arbutin, followed by procyanidin B1 and chlorogenic acid. In 'Conference' and 'Abate Fetel', higher arbutin content levels were measured above the graft union, while in the incompatible scion of 'Williams' on quince MA higher arbutin content levels were measured below the graft union. In all three observed cultivars (in 'Conference' the difference was not significant) grafted on Fox 11 rootstock, the highest content of arbutin was measured below the graft union. The results indicate that not only catechin and procyanidin B1, but also arbutin and several flavonols could be involved in graft incompatibility. All cultivars grafted on quince rootstocks had higher levels of epicatechin and procyanidin B2 below the graft union, even though some differences were not significant. It seems that those phenols do not affect pear incompatibility. A severe incompatibility between Fox 11 rootstock and 'Williams' was detected.

Epidemiological aspects of ‘CandidatusPhytoplasma pyri’ transmission

Studies were carried out on pear decline epidemic in an experimental field located in Pignataro Maggiore (Caserta, Italy) where ‘William’, ‘Comice’ and ‘Conference’, pear varieties were grafted on the rootstocks ‘Quince A’ (EMA), ‘Farold 333’, ‘Quince C’, Farold 282’, ‘Farold 40’, ‘Farold 87’, ‘BP1’, ‘Farold 51’ and assessed their different susceptibility to ‘Candidatus phytoplasma pyri’ infection. The research continued to study susceptibility of Pyrus betulaefolia and a selection of Cydonia oblonga, Quince BA29 rootstocks. Five plants for each of the same three varieties, grafted on the two rootstocks were used for graft and insect inoculation with ‘Ca. P. pyri’ and controlled for two years for symptom expression and pathogen presence. None of the combination studied showed differences in susceptibility to the pathogen.

Rootstocks affect pear (Pyrus communis) tree growth through extent of node neoformation and flowering with key differences to apple.

Improved knowledge of rootstock effects on pear (Pyrus communis L.) tree development is required before early assessment of rootstock breeding populations can be improved. Two cultivars, 'Doyenné du Comice' and 'Concorde', were grafted on Pyrus calleryana Decne. (vigorous), Quince BA29 (semi-vigorous) and Quince C (semi-dwarfing) rootstocks. Growth of the compound trees was studied over 2 years after grafting and flowering was recorded in the spring of the third year. Using architectural analysis, annual shoot types common to all treatments and closely connected to the patterns of extension of preformed and neoformed metamers were identified and the differences among rootstock vigour treatments were quantified by proportions of these shoot types. Rootstock affected node neoformation, which was highest in the treatment with P. calleryana. The extent of sylleptic branching varied among the treatments, whereas the budbreak along the primary-axis in the second year of growth was unaffected, hence, the number of proleptic secondary axes was largely determined the primary-axis node number developed in year one. Spring flowering first occurred in the third year of tree growth and its intensity was influenced by rootstock. Quince C, the least vigorous rootstock, produced the highest number of floral buds. Flowering was delayed in young pear trees compared with apple, as shown in previous studies, so we conclude flowering does not play such a pivotal role in secondary axes development and early tree dwarfing by rootstock as has been observed in apple.

EVALUATION OF PEAR ROOTSTOCK SELECTIONS

European pear (Pyrus communis L.) is in Italy predominantly grown on clonal quince (Cydonia oblonga Mill.) rootstocks. However, this grafting combination shows several problems including poor graft compatibility, susceptibility to lime-induced iron chlorosis and pear decline, which are normally not observed when P. communis is used as rootstock. Since 1979, the University of Bologna (Italy) has undertaken a breeding programme to obtain new clonal pear rootstocks and in 1996 two clones (Fox 11 and Fox 16) were released. Recently, the programme focused on clones with a marked size-controlling aptitude and high yield efficiency. In 2002 and 2004 two experimental trials were arranged to evaluate the performances of cultivars ‘Abbe Fetel’, ‘Conference’ and ‘Bartlett’ grafted on eight pear clones of Bologna University (A74, C19, C91, D46, D50, E82, E105 and Fox 9), Farold® 40 Daygon and quinces BA29, MC and Sydo®. Fox 9 showed a slightly higher vigor and yield performance compared to quince BA29, and good fruit quality. In addition, Fox 9 showed high environmental adaptibility, good suitability to be micropropagated and high graft compatibility with the tested cultivars. Based on these findings, in 2008 Fox 9 was released as a new rootstock for P. communis and the application for community plant variety rights (EU patent) was lodged. Among the other pear selections tested, D46 and D50 induced good yield but also the highest vigour, while C91 was interesting for the moderate growth.

PERFORMANCE OF 'COSCIA' PEAR (PYRUS COMMUNIS) ON NINE ROOTSTOCKS IN THE NORTH OF ISRAEL

Abstract The vegetative and reproductive performances of ‘Coscia’ pear ( Pyrus communis L.) grown on nine rootstocks [OHF 69, OHF 97, OHF 217, OHF 333, OHF 513 and BP 1 ( P. communis ), clonal seedling (Davis AxB) of Pyrus betulifolia and quince BA 29 and EMA ( Cydonia oblonga )] were compared during a 9-year period. The trial was conducted at the Experimental Station ‘Avnei Eitan’ in northern Israel (elevation 400 m above sea level, a.s.l.), on a well-drained soil with pH 7.1. Trees were planted in December 1998, spaced at 4.0 m × 2.0 m and trained with a central axis. The most vigorous trees were on P. betulifolia seedlings, followed by the four OHF rootstock (69, 97, 333, 513) and BP 1 (with no significant difference between them). All the above rootstocks demonstrated greater vigor than OHF 217 and quince BA 29 or EMA. The highest cumulative yields per tree were harvested from trees on the four OHF rootstocks (69, 97, 333, 513) and P. betulifolia followed by the BP 1. The two quince rootstocks, as well as OHF 217, had the lowest cumulative yield and the lowest yield of large fruit. A positive correlation was found between the vigor of the tree, as affected by the rootstock, and both the total yield and the fruit size. We conclude that in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for a weak cultivar is the first requirement for establishing an orchard.

Influence of cultivar and rootstock on early growth and syllepsis in nursery trees of pear (Pyrus communis L., Rosaceae)

A two-year field study was conducted to examine the capacity of spontaneous formation of long sylleptic shoots (LSS) in nursery trees of pear cvs. 'Abbe Fetel', 'Conference' and 'Starking Delicious' grafted on Quince MA (MA) and Quince BA 29 (BA 29) rootstocks in a nursery during the first year after bud grafting. Tree height (TH), trunk diameter (TD) - 10 cm above the bud union and number of LSS were measured at the end of each season. The TH was measured from the ground level. The highest number of LSS was developed by cv. 'Abbe Fetel' in both the seasons, and the lowest by cv. 'Starking Delicious'. Tree height and TD were highly significantly affected by the cultivar in both the years and by the rootstock in 2008. The interactions between them did not significantly affect the examined parameters. The study showed that the early growth and syllepsis of pear nursery trees during the first year after bud-grafting were incomparably more affected by the cultivar than by the rootstock under similar weather conditions and on the same soil in a crop rotation system.

Sodium induces simultaneous changes in cytosolic calcium and pH in salt-tolerant quince protoplasts

Previous experiments with salt-resistant quince BA29 (Cydonia oblonga cv. Mill.) have shown that this cultivar takes up sodium transiently into the cytosol of shoot protoplasts only in the absence of calcium chloride, or at <1mM calcium chloride. Addition of NaCl > or =100mM to single protoplasts from in vitro-cultivated quince in the presence of 1.0mM calcium induced instant changes in the cytosolic concentrations of calcium and protons. These changes were investigated by use of tetra [acetoxymethyl] esters of the fluorescent stilbene chromophores Fura 2 and bis-carboxyethyl-carboxyfluorescein (BCECF), respectively. The cytosolic Ca(2+) dynamics in the protoplasts were dependent on the concentration of NaCl added. The changes in calcium differed in amplitude and final concentration and were correlated in time mainly with changes in pH. Addition of 100-400mM NaCl to the protoplasts caused an oscillating increase in the cytosolic level of calcium, and then a decrease. Addition of mannitol, of equiosmolar concentration to NaCl, did not increase the cytosolic calcium concentration. Moreover, there was no increase in cytosolic calcium when NaCl was added in the presence of calcium binding ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetra acetic acid (EGTA), or lantan or verapamil, two inhibitors of plasma membrane calcium channels. Therefore, we conclude that, in salt-resistant quince, sodium induces an influx of calcium into the cytosol by plasma membrane calcium channels, and a simultaneous increase in cytosolic pH. Because these changes were obtained in the presence of 1mM calcium in the medium, they were not due to sodium uptake into the cytosol.

Performance of ‘Coscia’ pear ( Pyrus communis) on nine rootstocks in the north of Israel

The vegetative and reproductive performances of ‘Coscia’ pear ( Pyrus communis L.) grown on nine rootstocks [OHF 69, OHF 97, OHF 217, OHF 333, OHF 513 and BP 1 ( P. communis), clonal seedling (Davis AxB) of Pyrus betulifolia and quince BA 29 and EMA ( Cydonia oblonga)] were compared during a 9-year period. The trial was conducted at the Experimental Station ‘Avnei Eitan’ in northern Israel (elevation 400 m above sea level, a.s.l.), on a well-drained soil with pH 7.1. Trees were planted in December 1998, spaced at 4.0 m × 2.0 m and trained with a central axis. The most vigorous trees were on P. betulifolia seedlings, followed by the four OHF rootstock (69, 97, 333, 513) and BP 1 (with no significant difference between them). All the above rootstocks demonstrated greater vigor than OHF 217 and quince BA 29 or EMA. The highest cumulative yields per tree were harvested from trees on the four OHF rootstocks (69, 97, 333, 513) and P. betulifolia followed by the BP 1. The two quince rootstocks, as well as OHF 217, had the lowest cumulative yield and the lowest yield of large fruit. A positive correlation was found between the vigor of the tree, as affected by the rootstock, and both the total yield and the fruit size. We conclude that in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for a weak cultivar is the first requirement for establishing an orchard.

Nitrogen distribution, remobilization and re-cycling in young orchard of non-bearing ‘Rocha’ pear trees

In newly planted orchards, special attention must be paid to fertilization to build up the permanent structure of the trees so that high yield and fruit quality can be reached later on. Nitrogen (N) plays a major role in the fertilization plan, although few studies have assessed its use efficiency in young non-bearing trees, especially in field conditions. In this work, 1–3 years old ‘Rocha’ pear trees, grafted on quince BA29, were planted in a Mediterranean region, and fertigated with 6 g N tree −1 year −1 as ammonium nitrate with 5 at.% 15N enrichment to study the fertilizer N uptake during the vegetative cycle, the overall fertilizer N use efficiency at the end of each year, and the plant–soil N balance for this period. Nitrogen remobilization and the re-cycling of N from senescent leaves were also studied by fertilizing some pear trees with 10 at.% 15N enrichment. Nitrogen uptake was minimum at bud break and peaked in June/July remaining more or less constant until leaf fall. About 25% of the fertilizer N taken up by 3 years old trees in the previous year was found in the new tissues formed (flowers, leaves and 1-year-old shoots), reaching 27% when fine roots were also included. In those trees, 32% and 54% of the 15N stored in the previous year in the trunk and older shoots, respectively, were mobilized to the new growth in the following year. Fertilizer N use efficiency by trees increased from the first to the third year but was generally small (6%, 14% and 33%), and estimated N losses were large (89%, 46% and 53%, respectively in the first, second and third years). Irrigation water and soil provided more N to the trees than fertilizer N.

Performance of ‘Coscia’ pear (Pyrus communis) on seven rootstocks in a warm climate

SummaryThe vegetative and reproductive performance of ‘Coscia’ pear (Pyrus communis L.) growing on seven rootstocks [OHF 69, OHF 97, OHF 513 and BP 1 (P. communis), clonal seedling (Davis AxB) of P. betulifolia, and quince BA 29 and EMA (Cydonia oblonga)] were compared over an 8-year period. The trial was conducted at the Experimental Orchard Farm Station in northern Israel, on a well-drained soil with pH 7.5. Trees were planted in December 1998 at a distance of 4.0 m 2.0 m, and trained with a central axis. The most vigorous trees were on P. betulifolia seedling, followed by BP 1 and the three OHF rootstocks (69, 97, 513). All the above rootstocks demonstrated greater vigour than quince BA 29 or EMA. The reason for this effect, at least in part, appeared to be the excellent water status (high midday stem water potential values) of trees on P. betulifolia in comparison with the other rootstocks. The highest cumulative yields per tree were harvested from trees on P. betulifolia and BP 1, followed by the three OHF rootstocks (69, 97, 513). However, the highest cumulative yield of large fruit (> 60 mm) was obtained from trees on P. betulifolia, followed by the OHF series and BP 1. The two quince rootstocks had the lowest cumulative yield, and the lowest yield of large fruit. A positive correlation was found between the vigour of the tree, as affected by the rootstock, and both total yield and fruit size. We conclude that, in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for the weak scion cultivar is the first requirement for establishing an orchard. Fruit quality at harvest and during cold storage were examined for fruit from three rootstocks only. The highest soluble solids content values at harvest were obtained in fruit grown on quince EMA, compared to values for BP 1 and P. betulifolia fruit.

Performance of the pear (Pyrus communis) cultivar William's Bon Chretien grafted on seven rootstocks

The performance of the pear (Pyrus communis L.) cv. William’s Bon Chretien (William’s BC) grafted on 7 rootstocks was evaluated over a period of 8 years. The scions of the cultivar William’s BC were grafted on the following 7 rootstocks: (i) P. communis seedlings, (ii) quince BA 29, (iii) quince A, (iv) Pomology Institute (PI) 1, (v) PI 5, (vi) PI 27, and (vii) quince Komotinis (iv–vii are Greek local quince seedlings). Compatibility of William’s BC with P. communis, PI 1 and PI 27 was excellent and no tree losses occurred. The highest yield per tree was recorded when William’s BC was grafted on PI 5 rootstock, although it was not significantly different from P. communis. The lowest yield was recorded when the cultivar was grafted on BA 29 rootstock. Production efficiency of William’s BC was highest when grafted on PI 27, intermediate on quince A, PI 1 and PI 5 and lowest on P. communis. Iron concentration of leaves of scions grafted on P. communis, BA 29, quince A and quince Komotinis were significantly lower than those grafted on PI 5. From the results it is concluded that the rootstocks PI 1 and PI 27 are suitable for the cv. William’s BC under Greek or other similar climatic conditions.

Susceptibility of Some Stone and Pome Fruit Rootstocks to Crown Gall

The susceptibility of different fruit rootstocks to crown gall disease was investigated in greenhouse and field experiments with numerous strains of Agrobacterium tumefaciens over three years. Plants were inoculated in the roots and shoots for pot experiments. Field experiments were performed in a naturally contaminated nursery plot. The genotypes Prunus dulcis and P. persica showed a high level of susceptibility to A. tumefaciens. Among the stone rootstocks, bitter almond was highly susceptible in all experiments. Apricot and Cadaman rootstocks displayed low susceptibility but larger galls, showing that there was no relation between rootstock susceptibility and gall size. Among pome rootstocks, quince BA29 was resistant to the disease, while MM106 was susceptible in potted trials; however, in the field essays, pome rootstocks did not become galled, possibly because the strains had selected for and adapted to stone rootstocks.

Efficacy of the Non-Pathogenic Agrobacterium Strains K84 and K1026 against Crown Gall in Tunisia

The non-pathogenic Agrobacterium radiobacter strain K84 and its genetically modified (GEM) strain K1026 were tested for their effectiveness against local Tunisian strains and two reference strains (C58 and B6) of the crown gall bacterium Agrobacterium tumefaciens. Tests in planta were carried out on herbaceous plants (tomato and tagetes) and on some sensitive rootstocks (bitter almond, peach almond hybrid GF677 and quince BA29). In vitro tests showed that both K84 and K1026 were effective and that the difference between these strains was not statistically significant. On tomato and tagetes, strain K84 was effective against all crown gall isolates with the exception of the A. tumefaciens reference strain B6. GEM strain K1026 was very effective against all isolates from Tunisia and against the reference strains. Both antagonistic strains significantly reduced the percentage of galled plants as well as the number of galls per plant. Under field conditions, both antagonists controlled crown gall effectively. Best results were obtained on the bitter almond-tree rootstock. Antagonist effectiveness was less evident on quince BA29 and peach almond GF677 rootstocks. The genetically modified strain K1026 is of interest in controlling crown gall disease in Tunisia.

Evaluation of pear rootstocks in an orchard

This study was conducted in the Research and Breeding Institute of Pomology in Holovousy in order to test some new pear rootstocks under the conditions of the Czech Republic. In a rootstock trial planted in spring 1996 five clonal rootstocks (OH &amp;times; F 69, OH &amp;times; F 87, OH &amp;times; F 230, OH &amp;times; F 333 and standard Quince BA-29) were compared with Red Barttlet, Conference and Lucas as test cultivars. In comparison with Red Barttlet, the cumulative yield per tree from 1996 to 2002 was the highest on &lt;br /&gt;OH &amp;times; F 69 and the lowest on OH &amp;times; F 333. The yield efficiency (kg/cm&lt;sup&gt;2&lt;/sup&gt;) was best on BA-29. The cultivar Conference had the highest total yield and yield efficiency on OH &amp;times; F 87. The lowest yield was on OH &amp;times; F 333. The cultivar Lucas was the most productive on OH &amp;times; F 87. In the sixth year after planting no difference was observed in growth vigour (indicated by trunk crosssectional area) between OH &amp;times; F clones with the cultivar Red Barttlet. The trees on BA-29 grew less. The tree size of Conference was largest for OH &amp;times; F 230 and smallest for OH &amp;times; F 333. The cultivar Lucas grew vigorously on OH &amp;times; F 69. Small trees were observed on the rootstock OH &amp;times; F 87. Fruit weight was higher on BA-29 than on OH &amp;times; F rootstocks with all cultivars. The production of &lt;br /&gt;suckers proved to be small with all cultivars on all rootstocks. The anchorage of all trees was adequate. No graft incompatibility has been detected yet. The results were processed statistically. &amp;nbsp;