Choice Of Rootstock Research Articles

Complex mixtures of viroids identified in the two main citrus growing areas of Iran

The citrus industry in Iran is based on graft propagation of local and imported cultivars on a limited number of rootstocks such as sour orange, Mexican lime and Bakraee, a local natural hybrid. Infection of the available cultivars with graft-transmissible agents, viroids in particular, may have deleterious effects on the productivity of citrus and, more importantly, limits the choice of rootstocks. Rootstocks other than sour orange and Mexican lime will be needed as a consequence of the introduction and spread of Citrus tristeza virus (CTV) in the country. In the present study, two cv. Sanguinello sweet orange and two cv. Duncan grapefruit trees were selected on the basis of the bark scaling symptoms observed on the trifoliate orange and Troyer citrange rootstocks. Analysis by sPAGE and Northern blot hybridization of nucleic acid preparations of Etrog citrons graft-inoculated with these sources revealed the presence of several viroids: Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd), the causal agents of exocortis and cachexia, respectively, as well as Citrus bent leaf viroid (CBLVd), Citrus dwarfing viroid (CDVd) and Citrus bark cracking viroid (CBCVd). These viroids were sequenced and compared with the corresponding reference sequences. To extend these results, samples from different citrus cultivars were collected in the two main citrus growing regions and analyzed for viroids. Of the 49 samples tested, 22 were viroid-positive, witnessing the occurrence of cultivars infected with CEVd, HSVd, CBLVd, CDVd, or CBCVd as mixed infections in the surveyed regions. One sample was also co-infected with the newly described Citrus viroid V (CVd-V).

Bioaccumulation of mineral elements in grapevine varieties cultivated in “La Mancha”

AbstractThe capacity of a plant to take up chemical elements is measured as the ratio of the element concentration in the plant and its concentration in the soil. This ratio is called the bioaccumulation index (BAC). The choice of rootstock and variety can differentially affect nutrient uptake of grapevine (Vitis vinifera L.). Generally, only slight differences can be observed in the accumulation of N, P, and Zn. In contrast, wide variations are found in the absorption of K, Ca, Mg, and Cl. While studies on plant nutrients and major elements have been carried out in vineyards, very few references concern the trace‐element concentrations in leaves. In the study described here, five varieties (Airén, Cencibel, Garnacha, Cabernet Sauvignon, and Chardonnay) grown on a Calcisol Petric or Typic Calcixerept (typical of La Mancha) were compared in terms of leaf trace‐element concentrations. A total of three samples (20 healthy and completely developed leaves from the middle part of the shoot) were collected from three different plants of the same variety. Leaves were dried, milled, and x‐ray fluorescence analysis was performed. It was found that the variety of grapevine influences the uptake of four of the major elements: Al (low in Garnacha, [0.4 ± 0.2] g kg–1), Ca (high in Cencibel, [32.6 ± 8.1] g kg–1), P (low in Airén, [0.9 ± 0.4] g kg–1) and K, which showed significant differences in almost all of the varieties (from [4.7 ± 1.8] g kg–1 in Cencibel to [8.0 ± 10.1] g kg–1 in Chardonnay). No statistically significant varietal differences were found for trace elements. The only exception was La, which was present at higher levels in the variety Cencibel ([7.5 ± 0.3] mg kg–1). This finding allows to assess the geochemical fingerprinting of calcareous soils regardless of the grapevine variety studied.

Irrigation scheduling under water shortage: investigation of scion-rootstock of peach and water deficit combinations

Adequate choice of variety, rootstock and irrigation techniques could be, together, sources of improvement of water use. A field experiment was carried out in northern Tunisia on two drip irrigated peach varieties grafted on two rootstocks. Two deficit levels, mild DI1 and severe DI2, were applied. Phenological survey allowed determination of the crop growth stages: initial, development, mid- and late-season. The average lengths of these crop stages were 32, 43, 49 and 136 days for early variety and 33, 49, 63, and 105 days for mid-season variety, respectively. Mean value of crop evapotranspiration (ETc) for the four growth stages was respectively 31, 115, 211 and 420 mm for early variety and 40, 128, 311 and 300 mm for mid-season variety. ETc was restricted with low ground cover to 25, 85, 150 and 280 mm. Tree development, yield and water needs were affected by water status, rootstock and climatic conditions. Threshold values of Ψstem of −1.5 and −2.0 MPa could be considered for mild and severe deficit irrigation. The water use of the soil water seemed to be more efficient with vigorous rootstock under mild deficit. Under extreme watering conditions, rootstock effects were negligible. Lack of chilling affected tree growth inducing reduced water requirements.

The impact of various grape stock cultivars on the As, Cu, Co and Zn content of the grape berry (must, seed)

Scientific research from the last decades showed that the inappropriate industrial and agricultural production caused an abnormal increase of the potentially toxic elements in the soil. Unfortunately the acidification of the soil is an increasing problem in Hungary. According to Várallyay et al. (2008) 13% of the Hungarian soils are highly acid. Accumulation of toxic elements differs in the genetically diverse plant species. The root of the plant constitutes a filter so that the rootstock is also kind of a filter system, which may prevent that the scion part (such as berry) accumulate high levels of various potentially toxic elements from the soil. The aim of research was to determine how different grape rootstocks influence the As, Co, Cu and Zn content of the musts and seeds. Thus, specifying which of the grape rootstocks takes up the lowest level of these 4 elements (As, Co, Cu and Zn), and accumulates in berries, so could reduce the potentially toxic element load of the grape berries. The grape rootstock collection of the University of Debrecen was set up in 2003 in 3x1 m spacing on immune sandy soil. Grafting of ‘Cserszegi fűszeres’ was started in 2010. We could evaluate yields harvested from 12 rootstock varieties of the experiment in October 2011. We obtained valuable differences in the arsenic, copper, cobalt and zinc concentrations of musts and seeds of ‘Cserszegi fűszeres’ grafted into different rootstocks. The results obtained from the 2011 harvest support the statement that the choice of rootstock might be an important factor to increase food safety. The differences in concentration of the four elements observed in case of the rootstock may have been caused on one hand by the rootstock effect, and on the other hand, the vintage effect has a very significant impact on the vines element uptake. Several years of experimental results will be needed to answer these questions.

Growth, gas exchange, water-use efficiency, and carbon isotope composition of 'Gale Gala' apple trees grafted onto 9 wild Chinese rootstocks in response to drought stress

To determine the effects of rootstock choice on the scion response to drought stress, we compared the vegetative growth, biomass accumulation, gas exchange, and water-use efficiency (WUE) of 'Gale Gala' apple (Malus domestica Borkh.) trees grafted onto nine wild Chinese Malus rootstocks. Compared with the well-watered control, drought treatment limited growth, as manifested by smaller increments in plant height (PH), trunk diameter (TD), total fresh biomass (TB), total dry biomass (TDB), total leaf area (LA), and relative growth rate (RGR). The extent of this effect differed among rootstocks. Stress conditions led to increases in the root/shoot ratio (RSR), leaf thickness (LT), water-holding capacity (WHC), carbon isotope composition (δ13C), and WUE. Decreases were noted in stomatal density (SD), leaf relative water content (RWC), chlorophyll content (Chl), net photosynthetic rate (P N), transpiration rate (E), and stomatal conductance (g s), again varying by rootstock. Those that are generally considered more drought-tolerant, e.g., M. sieversii, M. prunifolia, and M. toringoides, had smaller declines in PH, TD, TB, TDB, LA, RGR, SD, RWC, Chl, P N, E, and g s and proportionally greater increases in RSR, LT, WHC, δ13C, and WUE compared with the droughtsensitive M. hupehensis and M. sieboldii. These results suggest that moisture stress has a significant dwarfing effect in the latter two species. Based on WUE calculations, trees on drought-tolerant rootstocks showed higher tolerance when stressed, whereas those on drought-sensitive rootstocks were less tolerant, as indicated by their lower WUE values.

Influence of rootstock on antioxidant system in leaves and roots of young apple trees in response to drought stress

Grafting rootstocks are widely used to enhance plants resistance to various biologic and abiotic stresses. We determined how the rootstock genotype might influence plant responses to drought, using 2-year-old ‘Gale Gala’ apple trees grafted onto Malus sieversii and M. hupehensis. Under water stress, trees with the former as their rootstock had smaller reductions in rates of relative growth and photosynthesis, total biomass, leaf area, levels of leaf chlorophyll, and relative water content compared with those grafted onto the latter. They also had greater maximum photochemical efficiency and water-use efficiency. On the other hand, trees growing on M. sieversii rootstock had less production of superoxide radicals and hydrogen peroxide in both leaves and roots than those growing on M. hupehensis in response to drought stress. Furthermore, under drought conditions, leaves and roots from trees grafted onto M. sieversii had greater synthesis of ascorbic acid and glutathione, as well as higher activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. These results suggest that the choice of grafting rootstock can enhance drought resistance by improving the antioxidant system in a plant. Here, ‘Gale Gala’ trees grafted onto M. sieversii were more drought-resistant than those on M. hupehensis rootstock.

Influence of rootstock on drought response in young ‘Gale Gala’ apple (Malus domestica Borkh.) trees

Drought is a major environmental stress limiting plant growth, productivity, and survival worldwide. Rootstocks are widely used to enhance plants resistance to drought stresses. This study determined influence of rootstock on drought responses in 1-year-old 'Gale Gala' apple trees grafted onto Malus sieversii or M. hupehensis. Choice of rootstock resulted in differential response to drought stress. Specifically, M. sieversii caused less drought-induced reduction in relative growth rate, biomass accumulation, leaf area, leaf chlorophyll content, relative water content, photosynthesis rate and maximum chlorophyll fluorescence yield but greater increase in whole-plant water use efficiency compared to M. hupehensis. Secondly, compared with M. hupehensis, M. sieversii caused less drought-induced accumulation of reactive oxygen species but more increase in activities of antioxidant enzymes. In addition, xylem sap abscisic acid concentration was greater in trees grafted onto M. hupehensis than in those grafted onto M. sieversii under drought stress. 'Gale Gala' trees' response to drought stress was associated with the rootstock's genotype onto which it was grafted. Trees with M. sieversii as rootstock are more drought resistant than trees with M. hupehensis as rootstock, which suggests that M. sieversii can be widely used as rootstock in arid and semi-arid regions.

FACTORS AFFECTING RIND OIL CONTENT OF LEMON [CITRUS LIMON (L.) BURM. F.

Among the controllable and non-controllable factors affecting rind oil content of lemons, genetic (scion, rootstock) and environmental (growing conditions, canopy microclimate) factors play the most important role. 'Limoneira 8A', followed by 'Cicily', 'Lisbon' and 'Genoa' had the highest rind oil content, whereas 'Villafranca', 'Messina' and 'Yen Ben Lisbon' had the lowest. Rind oil content of 'Eureka' lemon was disappointingly low. Seedless cultivars, 'Eureka SL' and 'Lisbon SL', had ~18.0% higher rind oil content than the seeded cultivars from which they were derived. Fruit from lemon trees budded on non-invigorating rootstocks, e.g. X639 (a Cleopatra mandarin × Trifoliate orange hybrid), had the highest rind oil content, whereas rind oil content was low on invigorating rootstocks, e.g. rough lemon. South Africa has a diverse climate, and rind oil content from fruit produced in a hot, arid growing region (Upington) had the highest rind oil content, whereas fruit from relatively warm regions (Malelane and Marble Hall) ranked second, and rind oil content of fruit from a cooler region (Karino) was intermediate. Rind oil content from a cold growing region (Vaalharts) was the lowest. Regression analysis between rind oil content and cumulative heat units revealed a positive linear relationship, and in general, rind oil content increased with increasing heat unit accumulation. Following the sampling of fruit from different positions in a tree's canopy, light exposure was found to affect rind oil content of 'Eureka' lemon fruit. Fruit borne on the outside of trees, higher in the tree, north-facing or not within the hedgerow had the highest rind oil content. PAR data supports the hypothesis that rind oil content is correlated with light exposure. Therefore, the choice of scion cultivar and rootstock in a given growing region, together with judicious pruning to optimise light penetration into a tree’s canopy, contribute to enhanced rind oil yields.

Rootstock influences the response of pistachio ( Pistacia vera L. cv. Kerman) to water stress and rehydration

Pistachio cultivation requires the use of rootstock because grafting is the only form of vegetative propagation. The main commercial rootstocks are Pistacia integerrima L., Pistacia atlantica Desf., Pistacia terebinthus L. and Pistacia vera L. Pistachio is considered to be a drought and saline-resistant crop; however, there is little information describing varietal responses of rootstocks to water stress. Some studies have suggested that P. terebinthus L. is the most drought and cold resistant rootstock. The effect of the rootstock on the water relations of the grafted plant is crucial for improving crop performance under water stress conditions and for developing the best irrigation strategy. This work studied the physiological response to water stress of pistachio plants ( P. vera L. cv. Kerman) grafted onto three different rootstocks P. terebinthus L., P. atlantica Desf. and a hybrid from crossbreeding P. atlantica Desf. × P. vera L. Plant physiological responses were evaluated during a cycle of drought and subsequent recovery in potted plants. Parameters measured were soil moisture, trunk diameter, leaf area, leaf number, leaf and stem dry weight, stem water potential, leaf stomatal conductance. The results showed different responses of cv. Kerman depending on the rootstock onto which it had been grafted. The hybrid rootstock was associated with a higher degree of stomatal control and reduced leaf senescence compared to P. atlantica and P. terebinthus, despite being associated with the most vigorous shoot growth. P. terebinthus enabled very effective stomatal control but was also associated with the most rapid leaf senescence. P. atlantica was associated with less vigorous shoot growth and similar levels of water stress as occurred with the others rootstocks under conditions of high evaporative demand, which was associated with lower stomatal control. The selection of the most effective rootstock choice for different environmental conditions is discussed.

ALTERNATIVE TO MYROBOLAN ROOTSTOCK FOR APRICOT CULTIVATION

The choice of apricot rootstock is first determined by the soil conditions; the adaptation to particular soil conditions being crucial for tree survival. Additionally, growers could be interested in low-vigour rootstocks for better vigour control and fruit quality. In Switzerland, apricots are traditionally cultivated on Myrobolan, which is too vigorous for high soil fertility and, thus, not adapted for high-density planting. Therefore, an enlarged vigour range is needed in order to produce high quality fruits. The aim of this study was to assess the influence of different rootstocks on survival and agronomic performances of the cultivar Luizet. A trial with ten different rootstocks was carried out in 1992 in the conditions of central Valais (Switzerland). Trees were traditionally trained as free-standing multiple leader (5.0 m x 3.5 m; 571 trees/ha). The rootstocks were selected according to their compatibility with light-sandy soil, slightly limestone (pH 7.6) and to cover the largest vigour range. From the 3 rd to the 12 th year, vigour evolution (trunk cross-area), productivity, yield as well as fruit size were determined. Citation, Rubira and Jaspi showed a vigour reduction of 35 to 45% compared to Myrobolan, while GF655-2, W61, Pixy and Torinel showed a decrease of 15 to 25%. GF43 and Myrabolan were of similar vigour and Julior showed a 20% higher vigour. The productivity was increased by 30% for Citation and reduced by 3%, 4% and 33% for Jaspi, Torinel and Julior, respectively. These four rootstocks induced a better fruit weight compared to Myrobolan. High decline rate has been observed with GF655-2, W 61, Pixy and Rubira; therefore, these selections cannot be recommended in our conditions. On the contrary, Citation is promising where densification requires dwarfing rootstocks. Torinel is a good alternative to traditional Myrobolan, inducing a slight vigour reduction and better fruit size, and Julior could be useful where hillside situation or poor soil fertility require stronger vigour.

Occurrence and identification of citrus viroids from Sudan.

The Sudanese citrus industry is mainly based on oldline cultivars of grapefruit, sweet orange and willow leaf mandarin, grafted almost exclusively on sour orange. Infectionwith graft-transmissible agents, viroids in particular, may have deleterious effects on the productivity of these citrus species and, more importantly, limits the choice of rootstocks should sour orange be replaced by alternative rootstocks because of tristeza disease. Three cv. Foster pink grapefruit sources and one local selection of Nuri-16, a local sweet orange selection, proved to be infected by several viroids, including Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd), the causal agents of exocortis and cachexia, respectively. Cloning and sequencing of four HSVd isolates showed that in addition to the characteristic variants containing the “cachexia expression motif” or the “non-cachexia expression motif”, other variants were also present. To secure additional information, samples from 24 citrus species and cultivars were collected in 2008 from several citrus-growing regions and analyzed for the presence of viroids. The results confirmed that CEVd, HSVd, Citrus bent leaf viroid (CBLVd), Citrus dwarfing viroid (CDVd), and Citrus bark cracking viroid (CBCVd), but not Citrus viroid V (CVd-V), are widely spread throughout the surveyed areas. None of the collected samples was found to be viroid-free. The relationships between viroid infection and “gummy bark” and “Kassala disease”, two affections of unknown etiology, but with cachexia-like gum impregnations in the bark, are discussed.

Water relations of apple and influence on fruit quality (minireview)

The saving of soil water content and the improvement of adaptability of plants to periodical insufficient water and use of deficit irrigation technology become more important because of the occurrence of frequently dry periods. The water use efficiency of apples can be increased by the choice of appropriate rootstocks and determination of water requirement of varieties that depend on their growing periods and climatic factors. Depletion of soil water resources need to develop efficient irrigation techniques for quality apple production. A new deficit irrigation strategy (PRD) has been developed that based on partial water supply of root-zone. This does not result a decrease in the sizes and yield of the fruit. The larger fruit size and lower firmness in frequently irrigated trees can result in excessive internal growth stresses that cause higher rate of fruit splitting. Many studies revealed the relationship between irrigation and yield quantity. Recent researches investigate the effects of irrigation on apple fruit quality particularly on the colouration and post-harvest quality. Use of cooling irrigation improves the development of coluour an apple fruit but its schedule can influence on the incomes. Aroma volatiles are responsible for odour and contribute to overall flavour of the fruit and its processed products. Deficit irrigation had only affects some volatile aroma but no the all of concentrations in apple fruit. In the future the high apple quality for consumers could be provided with improvement of transpiration-yield model based on the water requirement of varieties and economic irrigation schedules.

Vegetative propagation of Ziziphus mauritiana var. Gola by micrografting and its potential for dissemination in the Sahelian Zone

The jujube tree (Ziziphus mauritiana Lam., Rhamnaceae family) is an exotic species which is commonly found in the Sahelian and Sudanian areas of Africa. A programme was undertaken in Senegal to introduce domesticated varieties and adapt them to the edaphic and climatic specificities of the Sahel. Research focussed on the ‘Gola’ variety, multiplied by an in vitro micrografting technique which is a miniaturisation of the apex splice, involving the aseptic grafting of miniature scions (5 to 10 mm long) onto the hypocotyl of seedlings in vitro. Studies reported here include the choice and preparation of rootstock, the micrografting technique, acclimation of the grafts, and transplantation to the field. The outcome of this research is the achievement of successful establishment of over 80% of the micrografts. However, more work is required to evaluate the transferability of the techniques through a study of their economic viability, as well as their acceptability to local people.

The Effects of Exogenous Bioregulators and Environment on Regular Cropping of Apple

Use of exogenous bioregulators (“hormones”) to adjust crop load in apple remains challenging to both researchers and producers. These hormones are sensitive to the rate and timing of application, to the physiological status of the tree, the choice of orchard system, variety and rootstock, and a myriad of cultural practices and environmental factors. All classes of plant bioregulators have been used over the past 30 to 40 years as chemical thinning materials. Most of the standard postbloom thinning programs involve application of a synthetic auxin, such as naphthalene acetic acid (NAA) in combination with carbaryl, a commonly used insecticide. The mode of action of these two compounds is not clearly understood. Gibberellins generally have not been effective thinning materials because of the negative impact on return bloom. Ethylene-releasing compounds have been used successfully as postbloom thinning materials. And cytokinins, particularly synthetic sources such as 6-BA, have been shown to effectively thin fruit and to enhance fruit size on many commercial varieties. The rate and timing of 6-BA applications are particularly critical to obtain the desirable thinning and size responses. Overall, these bioregulators are sensitive to temperature. The use of bloom thinning compounds and their efficacy in the Pacific Northwest will be discussed in the context of return bloom.

Effects of Salinity on Some Citrus Scion-Rootstock Combinations

Chloride and sodium concentrations, water relations and gas exchange parameters were measured on leaves of Clementine (Citrus Clementine Hort. ex. Tan) and Navel orange [C. sinensis (L.) Osb] scions grafted on Cleopatra mandarin (C. reticulata Blanco) and Troyer citrange (C. sinensis × Poncirus trifoliata) rootstocks grown at increasing levels of NaCl in the external medium. Other parameters affected by salinity such as growth and defoliation were also recorded.Scions on Cleopatra mandarin accumulated less Cl- in their leaves than did scions on Troyer citrange. Also, leaf Cl- levels in Clementine scions were lower than in Navel orange when both were grafted on the same rootstock. However, sodium concentration was lower in scions on Troyer citrange than in Cleopatra mandarin.Leaf water potential, stomatal conductance, photosynthesis and growth were reduced more in grafted plants of salt-treated Navel orange than those of salt-treated Clementine. However, choice of rootstock had little effect on salt-induced changes in these parameters. For each scion, reduction in leaf stomatal conductance was closely correlated with decrease in leaf water potential. Also, a significant correlation between photosynthesis and stomatal conductance was found.The results indicate that reductions in gas exchange parameters and growth at increasing salinity levels depended more on the scion type than on Cl- or Na+ concentration in leaves. Otherwise, leaf injury and defoliation were closely correlated with leaf Cl- concentration.

Influence of rootstock on nutrient acquisition by pistachio

Abstract The influence of rootstock selection on leaf nutrient concentrations in commercial pistachio (Pistacia vera cv. ‘Kerman') was studied. Five commercially important pistachio rootstocks were used. The pistachio rootstock Pistacia atlantica was clearly superior in enhancing leaf concentrations of the elements, boron (B), copper (Cu), zinc (Zn), and phosphorus (P) from a range of soil types. The influence of rootstock on leaf nutrient concentration was apparent both in grafted and non‐grafted trees and was most pronounced when leaf nutrient levels were low. Leaf B, Cu, and Zn concentrations were from 1.2 to 2.4 times higher in pistachio grafted to P. atlantica than in those grafted on other rootstocks. For Cu and Zn, elements that are often deficient in Californian pistachio orchards, the choice of rootstock was sufficient to overcome visual deficiencies of these elements. In soils low in a particular element selection of rootstock may significantly influence management decisions and the need for fertilizer supplementation. Two hybrid rootstocks, in which the efficient rootstock P. atlantica was crossed with the inefficient P. integerrima, had lower leaf nutrient concentrations than the P. atlantica parent. The mechanism of nutrient efficiency was not identified though correlation analysis suggests separate characteristics are responsible for the enhancement of Zn uptake as compared to B or Cu uptake. Improvement in nutrient efficiency may be possible in future breeding programs.

Root shoot interactions in passionfruit (Passiflorasp.) under the influence of changing root volumes and soil temperatures

SummaryPassionfruit are grown in the tropics and subtropics where mean monthly soil temperatures at 15 cm range from about 10° to 30°C. The choice of rootstock can also influence production with most industries exploiting either the purple (Passiflora edulis f. edulis) or golden passionfruit (P. edulis tflavicarpa). We examined the relationship between shoot and root growth in purple x golden hybrid E-23 grafted onto golden passionfruit seedlings. Growth was manipulated by varying the volume of the soil available to the roots or temperature of the root zone. Shoot and root growth increased as root zone volume increased from 0.3, 1.4, 4, 12 to 24 1. Shoot weight (Ws) was correlated with root weight (WR):WS = 12.697 + 5.272 WR + 0.195 WR2 (r2 = 91%, P<0.001), with the plants allocating a smaller proportion of dry matter to the roots as root weight increased. Differences in shoot growth with pot volume were not due to changes in water or nutrient status. In the temperature experiment, the two critical root z...

Rootstock-Scion Interactions Concerning Wine Making. I. Juice Composition Changes and Effects on Fermentation Rate with St. George and 99-R Rootstocks at Two Nitrogen Fertilizer Levels

The brush-wt/crop-wt ratio as influenced by rootstock and fertilizer treatment can be correlated to the chemical composition of the grapes. An analysis of covariance of regression data of the ogarithm brush wt/crop wt to total nitrogen in the juice indicated that this relationship was independent of variety with respect to principal (slope of regression lines). It was postulated that the significant elevation changes in these regression data were due primarily to leaf-area brush-wt variety differences or differences in pruning. The more vigorous rootstock (`St. George9) yields fruit with more total nitrogen, total acid, tannin, potassium phosphorus, ammonia, and biotin, and a higher pH. The ammonium nitrate treatment had only a small effect, the only significant response being an increase in total nitrogen in the juice for the treated vines. A significant effect of year X fertilizer on ammonia content of the juice was found. The choice of rootstock for a wine variety can alter the juice composition significantly and thus affect the fermentation rate of the must to an economically important degree.