Du Lot Research Articles

Influence of SO4 and Rupestris du Lot (Monticola) Rootstocks on the Production of Tangra Dessert Vine Planting Material

The role of the vine rootstock and its correct selection is the main step in creating vine plantations to achieve a balance between vine growth, yield and grape quality. The studies in this direction are aimed at determining the most suitable rootstock for the different vine varieties, with the objective of their optimal development. In 2018–2021, the agrobiological parameters of vines of Tangra variety, grafted onto two rootstocks – SO4 (Berlandieri×Riparia selection Oppenheim 4) and Monticola (Rupestris du Lot), with different disposal of the root system and affecting the growth vigour and development of the vines, were studied in the Experimental nursery for grapevine rootings of IASS “Obratzov Chiflik”, Ruse, Bulgaria. The experiment was carried out in two variants, each in four replications with 50 grafted cuttings with drip irrigation and micro-jet irrigation in the first month after planting for rooting. The study aimed to recommend the most suitable rootstock for grafting Tangra dessert seedless variety to avoid adverse modification changes caused by it. Monticola rootstock was found to influence positively on the percentage of premium rooted vines, forming a better root system and inducing better growth and maturing of the increment in the production of vine planting material, compared to vines, grafted onto SO4 rootstock.

Effect of drought on aquaporin expression in grafted and ungrafted grapevine cultivars

Drought stress severely affects growth, development and productivity in most agricultural crops. Since ancient times, rootstocks have been used to enable crop cultivation in unsuitable soil conditions. In the present study, three factors were evaluated: 1) cultivar: Vitis vinifera L. cv. ‘Horozkarası’ (drought-tolerant) and cv. ‘Kabarcık’ (drought-sensitive) were used; 2) rootstock: each cultivar was self-rooted and grafted onto ‘Rupestris du Lot’ rootstock; 3) drought stress: half of each cultivar/rootstock combination underwent drought stress and the other half was irrigated at field capacity for seven days. In order to estimate the responses of the cultivars, relative water content, proline content and aquaporin isoform expression levels (VvPIP2;1, VvPIP2;2, VvTIP1;1, and VvTIP2;1) were quantified. The results revealed that drought stress caused more reduction in relative water content (RWC) in ‘Kabarcık’ cultivar (drought-sensitive) than in ‘Horozkarası’ cultivar (drought-tolerant). Proline content increased in both cultivars in response to drought stress but to a relatively greater extent in the grafted ‘Kabarcık’ cultivar. Considering expression levels of genes, VvPIP2;1, VvPIP2;2, and VvTIP2;1 were downregulated whilst VvTIP1;1 was upregulated in the leaf. Both ‘Horozkarası’ and ‘Kabarcık’ cultivars showed similar trends in terms of their responses to drought stress. Grafting significantly increased the proline content in both cultivars exposed to drought stress. The rootstock conferred better drought protection to ‘Kabarcık’ cultivar than to ‘Horozkarası’ cultivar.

Comparative transcriptomics and metabolomics in Vitis vinifera ‘Malvasia’ and Vitis rupestris ‘Du Lot’ cultured cells provide insights in possible innate resistance against pathogens

Grapevine varieties showing putative resistance to pathogens are a promising alternative to reduce the impact of disease management. Despite research efforts in understanding pathogen susceptibility/resistance to pathogens, the mechanisms that regulate these processes remain unclear. To identify the molecular and metabolic mechanisms associated with putative different susceptibility to pathogens and/or constitutive resistance, comparative transcriptomics and metabolomics were carried out in cultured cells of V. vinifera ‘Malvasia’ and V. rupestris ‘Du Lot’. Transcriptomic analysis revealed a higher enrichment of genes involved in biosynthesis of cell wall proteins, PR protein, ROS activation, phenylpropanoid pathway, TIR-NBS-LRR proteins and WRKY transcription factors in V. rupestris compared to V. vinifera. 1H-NMR based metabolomic analysis highlighted that leucine, isoleucine, valine, threonine, alanine, γ-aminobutyric acid (GABA), glutamine, phenylalanine and pyruvate significantly increased in V. rupestris compared to V. vinifera. Conversely, glucose, sucrose, and fumarate significantly decreased in V. rupestris compared to V. vinifera. Our findings reveal distinct pre-constitutive defense systems in two species consisting in an up-regulation of genes and primary metabolites involved in plant defense responses. These responses could be constitutively activated in V. rupestris opening new insights for sustainable viticulture through improved breeding programs.

Genetic diversity and parentage analysis of grape rootstocks.

The maternal and paternal parentage of 36 rootstocks was determined and verified. The results of this study indicate that existing grape rootstocks are closely related to each other and have a narrow genetic background. Rootstocks are used to protect grapevines from biotic and abiotic stresses including phylloxera, nematodes, viruses, limestone-based soils, salinity and drought. The most important rootstocks were developed from three grape species between the 1890s and the 1930s in European breeding programs. In this report, we developed nuclear and chloroplast SSR fingerprint data from rootstock selections maintained in germplasm collections, compared them to develop a reference dataset, and carried out parentage analysis to resolve previously reported, and determine new, breeding records. We refined and updated the parentage of 26 rootstocks based on 21 nuclear and 14 chloroplast markers. Results indicate that 39% of the genetic background of analyzed rootstocks originated from only three accessions of three grape species: Vitis berlandieri cv. Rességuier 2, V. rupestris cv. du Lot and V. riparia cv. Gloire de Montpellier. Results determined that Rességuier 2 is the maternal parent for 14 commercial rootstocks, 9 of which are full-sibs with Gloire de Montpellier as the paternal parent. Similarly, du Lot is the paternal parent of nine rootstocks. The pedigree information for 28 rootstocks was determined or corrected in this study. The previously reported pedigree information for eight of the rootstocks was correct. The results found that the world's existing rootstocks have a narrow genetic base derived from only a few American grape species. Future rootstock breeding efforts should use a more diverse array of species to combat a changing climate and pest pressure.

Rootstock-scion interaction:3. Effect on the composition of Cabernet Sauvignon wine

Abstract The interaction among rootstock, scion and environment may induce different responses to the grapevine physiology and consequently to the grape and wine composition. The vineyards of Serra Gaúcha, Brazil, are established in soils that may have different physicochemical attributes. Furthermore, the grapevines are grafted on a wide diversity of rootstocks. Therefore, this study aimed to determine their effect on the wine composition of the Cabernet Sauvignon (CS) grafted on Rupestris du Lot, 101-14 Mgt, 3309 C, 420A Mgt, 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, featuring some genetic diversity altogether. The experimental design was in randomized blocks, with 15 treatments, three replicates and 10 vines per plot. The grapes were harvested at maturity for three years, and then wines were made in glass recipients of 20 L. When alcoholic and malolactic fermentations were over, the wine analyses were performed on twenty-five variables related to alcohol, acidity, dry extract, polyphenols and volatile compounds. The main results show that all variables were affected year by year, some of them by the rootstock and a few by the interaction between rootstock and year. The rootstock effect was observed mainly on variables related to alcohol, acidity and ashes. Results show that the CS/101-14 Mgt wine had higher alcohol content than CS/Dogridge and CS/Isabel wines, which was probably due to the 101-14 Mgt rootstock favoring an early grape ripening. However, higher pH values were observed in the CS/Rupestris du Lot, CS/5BB K and CS/Gravesac than CS/420A Mgt, CS/110 R and CS/Isabel wines. These results show that there is a diversity of rootstocks that can be used by the growers due to the Cabernet Sauvignon wine composition similarities.

Rootstock-scion interaction: 4. Effect on the sensory characteristics of Cabernet Sauvignon wine

Abstract It is known that rootstock can induce changes on grapevine yield components and on the physicochemical composition of musts and wines. However, its effect on the sensory characteristics of wines has been scarcely studied. For this reason, an experiment was conducted to determine the effect of 15 rootstocks on the sensory characteristics of Cabernet Sauvignon wine, whose grapevines were grafted on Rupestris du Lot, 101-14 Mgt, 3309 C, 420A Mgt, 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, which feature some genetic diversity altogether. The experimental design was in randomized blocks, with 15 treatments, three replicates, 10 vines per plot. Mature grapes were harvested, and wines were made in 20-L glass recipients. When alcoholic and malolactic fermentations were finished, the wines were bottled and stored at 18°C. Sensory analysis was performed in the next year, following international procedures. The tasting panel was formed by 12 experienced enologists, who evaluated the wines in individual cells separated by opaque glass. They were served monadically and the perception of each taster was recorded in 9-cm unstructured scale sheets. Twenty-two variables were evaluated, which were related to the visual, olfactory and taste aspects. The results show that the tasting panel was not able to detect significant differences (p> 0.05) of rootstocks in any variable related to the sensory characteristics of Cabernet Sauvignon wine.

Rootstock-scion interaction:5. Effect on the evolution of Cabernet Sauvignon grape ripening

Abstract The rootstock effect on grapevine yield components, grape must and wine composition and wine sensory characteristics were evaluated in previous studies. This experiment carried out over five years had the objective to determine the effect of the rootstock on the evolution of variables related to sugar and acidity contents of the juice during grape ripening. The treatments consisted of Cabernet Sauvignon grapevine grafted on rootstocks such as Rupestris du Lot, 101- 14 Mgt, 3309 C, 420A Mgt, 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel. The berries were sampled during the grape ripening period, on nine dates during the summer of each year. Taken to the laboratory, they were hand crushed and the juice was centrifuged to separate the solid and liquid phase, where the supernatant was then used for physicochemical analyses. The data were submitted to Principal Component Analysis (PCA) and polynomial regression analysis. The main results show that, at grape maturity, the PCA discriminated mainly the juices of CS/101-14 Mgt, CS/SO4 and CS/Gravesac, which had high density, total soluble solids, total soluble solids/titratable acidity ratio and pH, and CS/Dogridge and CS/Fercal, which had high titratable acidity. The density, total soluble solids, titratable acidity, total soluble solids/titratable acidity ratio increased as grape ripened, but the titratable acidity decreased. However, the increase or decrease rates were lower at the end of the grape ripening cycle according to the variable, and the total soluble solids having the highest increase (116.3%) and the titratable acidity the highest decrease (68.3%).

Rootstock-scion interaction: 2.effect on the composition of cabernet sauvignon grape must.

ABSTRACT - The interaction between rootstock, scion and the environment may induce different responses to the grapevine physiology and, consequently, to the grape composition. The vineyards of Serra Gaucha, Brazil, are established in different soil types, each with different morphological and physicochemical attributes. Moreover, the grapevines are grafted onto a diversity of rootstocks. Therefore, this study aimed to determine the effect of 15 rootstocks in the composition of the Cabernet Sauvignon (CS) grape must. The following rootstocks were used: Rupestris du Lot, 101-14 Mgt., 3309 C, 420A Mgt., 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, featuring some genetic diversity altogether. The experimental design was in randomized blocks with 15 treatments, three replicates, 10 vines per plot. The grapes were harvested at maturity for four years, and then crushed for winemaking. Next, the grape musts were centrifuged to separate the solid phase from the liquid phase, which was used for analyses related to sugar, acidity and minerals. The data were submitted to correlation analysis and Principal Component Analysis. The main results from the average of four years show that, in general, the grape musts of the CS/101-14 Mgt., CS/161-49 C, CS/3309 C, CS/Rupestris du Lot and CS/Gravesac combinations had high values of density, total soluble solids, pH and °Brix/titratable acidity ratio, and low titratable acidity, which was high with CS/99 R, CS/110 R, CS/Dogridge and CS/1103 P. Potassium had higher concentrations in the grape musts of CS/SO4 and CS/5BB K. Titratable acidity did not correlate with density and total soluble solids, but positively correlated with yield. Density, total soluble solids, and the concentration of potassium were positively correlated with pH. Index terms: Vitis vinifera, grapevine, grafting, composition, minerals.

ROOTSTOCK-SCION INTERACTION: 2. EFFECT ON THE COMPOSITION OF CABERNET SAUVIGNON GRAPE MUST

ABSTRACT The interaction between rootstock, scion and the environment may induce different responses to the grapevine physiology and, consequently, to the grape composition. The vineyards of Serra Gaúcha, Brazil, are established in different soil types, each with different morphological and physicochemical attributes. Moreover, the grapevines are grafted onto a diversity of rootstocks. Therefore, this study aimed to determine the effect of 15 rootstocks in the composition of the Cabernet Sauvignon (CS) grape must. The following rootstocks were used: Rupestris du Lot, 101-14 Mgt., 3309 C, 420A Mgt., 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, featuring some genetic diversity altogether. The experimental design was in randomized blocks with 15 treatments, three replicates, 10 vines per plot. The grapes were harvested at maturity for four years, and then crushed for winemaking. Next, the grape musts were centrifuged to separate the solid phase from the liquid phase, which was used for analyses related to sugar, acidity and minerals. The data were submitted to correlation analysis and Principal Component Analysis. The main results from the average of four years show that, in general, the grape musts of the CS/101-14 Mgt., CS/161-49 C, CS/3309 C, CS/Rupestris du Lot and CS/Gravesac combinations had high values of density, total soluble solids, pH and °Brix/titratable acidity ratio, and low titratable acidity, which was high with CS/99 R, CS/110 R, CS/Dogridge and CS/1103 P. Potassium had higher concentrations in the grape musts of CS/SO4 and CS/5BB K. Titratable acidity did not correlate with density and total soluble solids, but positively correlated with yield. Density, total soluble solids, and the concentration of potassium were positively correlated with pH.

Rootstock on vine performance and wine quality of ‘Syrah’ under double pruning management

In the Brazilian Southeast, the production of high quality wines is attained by a new management approach called double pruning. This management changes the harvesting of wine grape (Vitis vinifera L.) from wet summer to dry winter through a two pruning procedures carried out during the year. The first pruning is done during the winter to induce a vegetative cycle (all clusters are removed) and a second pruning is done during the summer to induce the reproductive cycle. In this study, ten different rootstocks were compared in order to optimize yield and wine quality of Syrah vines conducted under autumn-winter season by double pruning approach. Syrah grapevines grafted onto ‘Rupestris du Lot’ and ‘IAC 766’ showed the highest pruning weight, while ‘110 Richter’ and ‘161-49 Courdec’ induced the lowest cane vigor. The average production of two seasons identified ‘IAC 766’, ‘Kober 5BB’ and ‘Rupestris du Lot’ as the most productive rootstocks. In both seasons, the grape quality was more influenced by the plant development status than by rootstocks. ‘Syrah’ wine from vigorous and high yielding rootstocks, ‘IAC 766’ and ‘Rupestris du Lot’, showed satisfactory wine phenolic composition and alcohol/acidity balance. This study showed that vigorous rootstock increased yield without compromising grape and winter wine quality of Syrah grapevines subjected to double pruning management in the Brazilian Southeast.

Effect of rootstock on phenolic compounds and antioxidant properties in berries of grape (Vitis vinifera L.) cv. ‘Red Alexandria’

The present study aimed to investigate the effect of rootstocks on phenolic compounds and antioxidant capacities in berries of ‘Red Alexandria’ (Vitis vinifera L.). There were significant differences among 15 rootstocks with respect to most of the parameters studied. Berries from ‘Saltcreek’ and ‘Rupestris du Lot’ contained the highest concentrations of glucose and fructose (85.00 and 99.55mgg−1FW, and 83.48 and 99.69mgg−1FW, respectively), while berries from ‘420A’ contained the lowest concentrations of sugars (62.49 and 74.23mgg−1FW). Rootstock had a significant influence on total phenolics, flavonoids, flavan-3-ols, anthocyanins and antioxidant profiles. In particular, anthocyanins in the peels were affected to more by the rootstock than on other secondary metabolites. Berry peels of ‘Saltcreek’ (4.13mgg−1) or ‘Macadams’ (4.07mgg−1) and ‘420A’ (0.23mgg−1) showed an 18-fold difference in anthocyanins. On the base of Principal Component Analysis, the results showed that the ‘Rupestris du Lot’ rootstock produced berries with higher reducing sugar, phenolic compounds and antioxidant capacities. In addition, a significant and positive correlation (P<0.01) was observed among total phenolics, flavonoids, flavan-3-ols, and antioxidant properties. Thus, considering berries quality and nutrition, ‘Rupestris du Lot’ and ‘Saltcreek’ rootstock could be suggested for Vitis vinifera L. under alike ecological conditions in Southern China.

ROOTSTOCK-SCION INTERACTION: 1. EFFECT ON THE YIELD COMPONENTS OF CABERNET SAUVIGNON GRAPEVINE

ABSTRACT The interaction between rootstock, scion and environment can induce different responses to the grapevine physiology. Thus, the aim of this study was to determine the rootstock effect on the yield components of Cabernet Sauvignon (CS) grapevine grown in the Serra Gaúcha viticultural region. The experimental design was completely randomized blocks, with 15 treatments, three replicates and ten vines per plot. The results show that all variables evaluated were significantly affected by the year and the rootstock. The CS/Solferino was among other combinations influenced by the year and had higher significant yield/ vine. Indeed, it was higher than that CS/Rupestris du Lot, CS/101-14 Mgt., CS/3309 C, CS/5BB K, CS/161- 49 C, CS/1103 P. and CS/Isabel. The number of clusters/bud, per burst bud and per vine and the weight of clusters were affected by the rootstock as well. Pruning weight/vine, yield/pruning weight, leaf area/vine, leaf area index and leaf area/fresh fruit weight are variables related to the physiology of grapevine which were also affected by the rootstock. In general, rootstocks had adapted well to the environment where the experiment was carried out, giving vigor and high yield to Cabernet Sauvignon grapevine, which means that they may be used by grape growers in this region. However, the choice of the right rootstock depends on various aspects, such as those related to the soil characteristics, climate conditions, grape varieties, and even clones, and production purposes.

Molecular analysis of genetic diversity among vine accessions using DNA markers.

Viticulture presents a number of economic and social advantages, such as increasing employment levels and fixing the labor force in rural areas. With the aim of initiating a program of genetic improvement in grapevine from the State University of the state of Rio de Janeiro North Darcy Ribeiro, genetic diversity between 40 genotypes (varieties, rootstock, and species of different subgenera) was evaluated using Random amplified polymorphic DNA (RAPD) molecular markers. We built a matrix of binary data, whereby the presence of a band was assigned as "1" and the absence of a band was assigned as "0." The genetic distance was calculated between pairs of genotypes based on the arithmetic complement from the Jaccard Index. The results revealed the presence of considerable variability in the collection. Analysis of the genetic dissimilarity matrix revealed that the most dissimilar genotypes were Rupestris du Lot and Vitis rotundifolia because they were the most genetically distant (0.5972). The most similar were genotypes 31 (unidentified) and Rupestris du lot, which showed zero distance, confirming the results of field observations. A duplicate was confirmed, consistent with field observations, and a short distance was found between the variety 'Italy' and its mutation, 'Ruby'. The grouping methods used were somewhat concordant.

STUDY ON THE INFLUENCE OF RUPESTRIS DU LOT ROOTSTOCK ON SOME TECHNOLOGICAL TRAITS OF MUSCAT RUSENSKI AND SUPER RAN BOLGAR TABLE GRAPE CULTIVARS

The choice of rootstock is important not only for the power that it induces on the grafted variety of grapes, but also with respect to its effects on mineral nutrition, content of sugars, total acids and other technological traits. Two table vine varieties-Misket Rusenski and Super ran Bolgar were the objective of the study, grafted on two different SO4 rootstocks (which is widely used in practice and thus accepted control) and Rupestris du Lot (with common name Montikola). A total of 12 technological traits were reported for both varieties during the vegetation. Data obtained were statistically analyzed using Fisher (F) and Student (t) evaluation criteria. The results showed different levels of significance of the individual traits in both varieties using Rupestris du Lot rootstock compared to the control. Via Fisher's criterion it was found that 58 % of the traits showed significant differences in Montikola rootstock compared to the control, as the comparison was made based on variability of the traits, while when using the Student criterion for statistical evaluation, the percentage was only 33. The highest significance was reported in the influence of the rootstock on the traits: number of seeds in 100 berries and resistance of berry to pick up from the fruit stalk for cv. Misket Rusenski, determined via both criteria. Comparing the samples tested regarding variability, significant differences were reported of Rupestris du Lot rootstock for the traits: % of berries in grapes and % of mesocarp in berry mass for the same variety. Rupestris du Lot rootstock has significant influence on content of sugars, total acids and mass of 100 seeds in cv. Super ran Bolgar (by the criterion of Fisher) and traits: % of mesocarp of berry mass and % of skin of berry mass (found by the criterion of Student). These traits influence significantly on tasting qualities of grapes and technological qualities of wine. As a result of the analysis of both vines (Misket Rusenski and Super ran Bolgar) a high degree of variability of the values of some technological traits was determined, and it is recommended both criteria to be used for better statistical evaluation. Keyword: Rupestris du Lot rootstock, statistical evaluation, table vine varieties Misket Rusenski and Super ran Bolgar (Vitis vinifera L.), technological traits

Assessing the quality of care in a new nation: South Sudan's first national health facility assessment.

We adapted a rapid quality of care monitoring method to a fragile state with two aims: to assess the delivery of child health services in South Sudan at the time of independence and to strengthen local capacity to perform regular rapid health facility assessments. Using a two-stage lot quality assurance sampling (LQAS) design, we conducted a national cross-sectional survey among 156 randomly selected health facilities in 10 states. In each of these facilities, we obtained information on a range of access, input, process and performance indicators during structured interviews and observations. Quality of care was poor with all states failing to achieve the 80% target for 14 of 19 indicators. For example, only 12% of facilities were classified as acceptable for their adequate utilisation by the population for sick-child consultations, 16% for staffing, 3% for having infection control supplies available and 0% for having all child care guidelines. Health worker performance was categorised as acceptable in only 6% of cases related to sick-child assessments, 38% related to medical treatment for the given diagnosis and 33% related to patient counselling on how to administer the prescribed drugs. Best performance was recorded for availability of in-service training and supervision, for seven and ten states, respectively. Despite ongoing instability, the Ministry of Health developed capacity to use LQAS for measuring quality of care nationally and state-by-state, which will support efficient and equitable resource allocation. Overall, our data revealed a desperate need for improving the quality of care in all states.

Reação de porta-enxertos de videira a Pratylenchus brachyurus e Pratylenchus zeae

The aim of this study was to evaluate the reaction of eight grapevine rootstocks to root-lesion nematodes. Cuttings of the rootstocks Kober, SO4, 101-14, R99, 420-A, Rupestris du Lot, Riparia do Traviu and Telek 5C, provided by the Centro APTA de Frutas/IAC, were planted in 5-L pots containing a 2:1 (v:v) soil and sand mixture, and kept in greenhouse. After four months, they were inoculated with 1,200 specimens of Pratylenchus brachyurus or P. zeae. Maize was used for detecting the inoculum viability. After 180 days of the inoculation, the root systems of the plants were collected along with 100 cm3 soil for evaluating the number of nematodes. Maize plants were evaluated 90 days after inoculation and each pot received a new seedling, which was evaluated along with the rootstocks. All rootstocks exhibited immunity to P. brachyurus and P. zeae, because the final populations in the root systems and the reproduction factor were zero. It was recovered six and 11 specimens of P. zeae in samples from cultivated soil with Kober and 420-A rootstock, respectively. In the maize, the respective average populations of P. brachyurus and P. zeae were 8,040 and 6,940. The rootstocks are potentially valuable for infested areas.

Comparative evaluation of oxidative enzyme activities during adventitious rooting in the cuttings of grapevine rootstocks

This study investigated changes in peroxidase (POX) and polyphenol oxidase (PPO) activities through adventitious rooting in hardwood cuttings of grapevine rootstocks. Three grapevine rootstocks with different propensity to produce adventitious roots were selected: recalcitrant (Ramsey), non-recalcitrant (Rupestris du Lot) and intermediate (99R) cultivars. The averages of root number at 65 days were 96 in Lot, 76 in 99R and 30 in Ramsey. Both enzyme activities characteristically increased before adventitious rooting, regardless of rooting ability of the rootstocks, and then decreased. POX activity increased in Ramsey cuttings at 22 days, in Lot and 99R cuttings at 14 days after planting, and then decreased gradually until 51 days. The highest POX activity was determined in Ramsey rootstock with the highest rooting ability and the lowest activity was determined in the rootstocks with the lowest rooting ability. PPO activity gradually increased in Ramsey rootstock cuttings from 10 days to 22 days, in Lot and 99R cuttings at 14 days, and then decreased until 51 days. A significant correlation was identified between high POX activity and adventitious rooting capability in rootstocks, but the same result was not determined with PPO activity. A recalcitrant rooting variety cannot increase POX activity sufficiently before rooting. Therefore applications that could increase POX activity in stem cuttings during rooting may facilitate increased rooting in such rootstocks.

Salinity Responses of Grafted Grapevines: Effects of Scion and Rootstock Genotypes

Two-year-old Sultana and Mke vines (Vitis vinifera L.) grafted onto Rupestris du Lot (Vitis rupestris Scheele) and 110 R (Vitis berlandieri Vitis rupestris) were grown in soil, sand, sphagnum peat and farmyard manure mixture (2:1:1:1 v/v) irrigated with 0.3, 2.7 and 5.45 dS m-1 NaCl solutions for a period of 60 days. Biomass accumulation, relative chlorophyll content, leaf water potential, stomatal conductance and transpiration were significantly reduced by salinity in all graft combinations. The inhibiting effect of salinity on growth varied according to the characteristics of the scion genotype and the level of salinity. The results imply the predominance of the scion genotype in determining variation in the leaf-level physiological characteristics of grafted vines because stomatal conductance and transpiration were higher in Sultana than in Mke at the same leaf water potential and the level of salinity, regardless of the rootstock genotype. NaCl treatments did not affect leaf Cu concentration while inducing significant Na, K, Ca, N, P, Mg, Fe, Mn and Zn elevations in the leaves of all scion/rootstock combinations. While salinity caused an increase in N content and a decrease in K content in the roots of all graft combinations, it had no influence on Ca, P, Cu and Zn concentrations. In contrast to the Sultana grafted vines, NaCl salinity led to a decrease in Mg, Fe and Mn concentrations in the roots of Mke grafted vines. Nevertheless, ion accumulation in leaves and roots of grafted vines under saline or non-saline conditions was controlled predominantly by the genotype of the scion. In response to salinity, Sultana grafts accumulated higher amounts of ions in their leaves than in their roots. However, in Mke, higher ion concentrations were seen in the roots. Therefore, the increase in the transport of inorganic ions up to the leaves seems to be the major component of osmotic adjustment in salt-stressed Sultana vines.

THE ASSESSMENT OF DIFFERENT ROOTSTOCKS TO THE PEAR TREE CULTIVAR 'CARRICK'

Low fruiting is the main problem related to the pear production in Brazil, which makes the country one of the major pear importers. This research aimed to evaluate different rootstocks to pear tree cultivar 'Carrick' to be used in commercial orchards. The experiment was carried out in Pelotas/RS, located at latitude 31°52'00S, longitude 52°21'24W Greenwich and altitude of 13.24 m. The orchard was set up in 2002 with a density of 2000 trees.ha -1 . The trees were conducted in slender spindler system trained on three-wire support with a dripping irrigation system. The treatments assessed were 13 quince rootstocks (Cydonia oblonga) cultivars 'Adams', 'Alaranjado', 'BA 29', 'Bereczcki', 'Champion', 'Du Lot', 'D'Vranja', 'EMC', 'Inta 267', 'Lageado', 'Melliforme', 'PineApple' and 'Portugal' and one Pyrus calleryana. The experimental design utilized was a complete randomized block with 3 replications of 5 trees each. The variables assessed were rootstock/scion trunk diameter, tree height, canopy volume, pruning weight, productivity and productivity efficiency. 'D'Vranja' rootstock provided the highest vigor to the tree, whereas the rootstock cultivars 'Du Lot', 'Lageado' and 'Bereczcki' the lesser vigor, however not differing from most of the rootstocks in the study. The highest productivity was verified by using the rootstock 'Portugal' (1.12 t.ha -1 ), followed by 'EMC' that did not differ from 'D'Vranja' and 'BA 29'. 'D'Vranja' showed the highest vigor and also had the highest productivity efficiency (9.53), but did not differ from 'BA 29'. Although 'D'Vranja' provided more vigor to the tree, it is still a good rootstock alternative to the pear cultivar 'Carrick'.

EVALUATION OF GRAFT COMPATIBILITY BETWEEN QUINCE ROOTSTOCKS AND PEAR SCIONS

Commercial pear varieties worldwide are grafted on rootstocks of Pyrus and Cydonia. Quinces rootstocks have been widely used due to two beneficial characteristics provided to the scion tree as size reduction and yield precocity. However, most pear cultivars exhibit graft incompatibility when grafted on quince rootstocks due to physiologic and biochemical factors. Aiming to compare compatibility levels, 41 five-year-old scion/rootstocks combinations trained in medium/high density (2000 trees/ha) were measured in the region of Pelotas - RS, Brazil during 2007. The pear cvs. tested were 'Carrick', 'Seleta', 'Packham's Triumph' and 'William's Bon Chretien'; and the rootstocks were Pyrus calleryana and 19 quinces cvs: 'Adams', 'Alaranjado', 'Alongado', 'BA 29', 'Bereczcki', 'Champion', 'De Patrans', 'Du Lot', 'D'Angers', 'Vranja', 'EMC', 'Inta 267', 'Lageado', 'Maca', 'Melliforme', 'PineApple', 'Portugal', 'Radaelli' and 'Smyrna'. Evaluations were performed by visual observations and measurements of the graft-point development (mm), five cm above and five cm below. Experimental design utilized was a randomized complete block with three replications of five trees each. The largest trunk diameters of 'Carrick', 'Seleta' and 'William's' (42.56, 59.29 and 45.74 mm, respectively) were provided by the rootstock P. calleryana. Regarding to scion trunk diameter in relation to the rootstocks: 1) 'William's' had the smallest diameters with the utilization of 'EMC', 'Portugal' and 'Radaelli' (16.42, 16.57 and 17.64 mm, respectively); 2) 'Packham's' had the smallest diameters provided by 'EMC', 'Portugal' and 'Adams' (15.03, 17.34 and 19.09 mm, respectively); 3) 'Carrick' was affected by lesser trunk development when raised on 'Alaranjado', 'Du Lot', 'Adams', 'Bereczcki' and 'Champion'. 'Portugal' and 'EMC' had a considerable visual and measured incompatibility whether grafted into 'Carrick'. For 'Packham's' this incompatibility was observed with the use of P. calleryana, 'Adams' and 'Portugal'. Among the interactions for 'Seleta' only P. calleryana did not show accentuated hypertrophy in the graft-point. In the 'William's' combinations this hypertrophy was more pronounced when grafted on rootstocks 'EMC', 'Bereczcki', 'Champion' and 'Melliforme'. Requesting for a better visualization and confirmation between quince/pear compatibility, further evaluations will be necessary observing the development and behavior of each interaction scion/rootstocks.