Izumrud

Main Characteristics

The new white technical grape variety Izumrud was developed by specialists from the FSBS Ya.I. Potapenko All-Russian Research Institute for Viticulture and Winemaking through the hybridization of varieties Donus and Platovsky. The variety belongs to the early ripening category. The average duration of the production period is 116 days, extending to 140 days in unfavorable, cool years. The sum of active temperatures required from the beginning of bud burst to the onset of technical maturity of berries ranges within 2200–2500 °C, with the average indicator over the years of study being 2632 °C. The grape variety Izumrud is characterized by high and stable productivity, with an average yield reaching 187 ц/ha; the average harvest per vine is 4.25 kg, fluctuating between 2.25 and 6.2 kg depending on the year. The bunches are cylindrical-conical, sometimes winged, of medium density, with an average weight of 114 grams. The berries are small, with an average weight of 1.9 grams, featuring a simple, harmonious taste. In the phase of full technical maturity, the average sugar accumulation is 231 g/dm³ (23.1%), and the titratable acidity of the berry juice remains at a level of 6.0 g/dm³. The product is recommended for commercial cultivation in Region 6.

Morphological Description of the Grape Variety Izumrud

Characteristic morphological features by which the grape variety Izumrud is identified:

• Leaf: fully formed leaves are of medium size, pentagonal in shape, weakly dissected, and five-lobed. The leaf blade has a medium-bullate surface. The coloration of the main veins on both the upper and lower sides is light green. The main veins on the upper side of the leaf blade are characterized by weak anthocyanin coloration.
• Leaf incisions: the upper incisions are small, open, and formed as an incoming angle. The lower incisions are small, open, and slit-like, often barely marked.
• Petiolar sinus: half-open, with a distinct V-shaped form.
• Teeth: the terminal teeth of the lobes are short and dome-shaped. The teeth along the margin of the leaf blade are small, dome-shaped with convex sides.
• Petiole: equal in length to the main vein of the leaf and has an intense wine-red color.
• Leaf pubescence: on the lower side of the formed leaf, there is dense bristly pubescence combined with medium or weak cobwebby pubescence.
• Flower: bisexual, with five stamens. The length of the stamen filaments slightly exceeds the total length of the pistil.
• Bunch and berry: the bunches are cylindrical-conical, equipped with short peduncles and stems. The berries are small (weighing 1.9 grams), rounded, yellow-green in color, and contain two to three seeds. The berry separates easily from the peduncle during harvesting. The skin is thin but strong; the pulp is slightly firm and moderately juicy.

Features of Agricultural Technology

The grape variety Izumrud is characterized by a medium vigor of vine growth and a good level of mature annual shoots, exceeding 80%. The fruiting indicators are consistently high: the proportion of bearing shoots per vine averages 83%, the fruiting ratio is 1.3, and the productivity of a single shoot reaches 135 grams. The plantations are cultivated in a grafted, uncovered culture on the Kober 5BB rootstock with a vine planting scheme of 3.0 × 0.75 meters. The recommended training type is a double-arm horizontal cordon with a trunk height of 100 cm. The management technology provides for short pruning of fruiting canes to 3–4 buds. The grape variety Izumrud possesses high winter hardiness and can withstand drops in winter temperatures down to -25 °C. The variety is highly resistant to fungal diseases: the average susceptibility to mildew is 2.0 points (maximum up to 3.0 points), to powdery mildew (oidium) is 2.0 points (maximum up to 2.5 points), and to gray mold is 0.5 points. This complex resistance allows for successful cultivation of the variety with only two preventive sprayings during the vegetative season.

Winemaking and Features of the Finished Product

The harvest of the variety Izumrud is technologically oriented toward the production of high-quality dry table wines. Processing and preparation of wine materials are carried out under micro-winemaking conditions. The finished dry wine is fully transparent and possesses an attractive pale straw color. The varietal aroma exhibits cleanness with characteristic notes of field herbs. The taste of the finished product is full and harmonious. The average physico-chemical parameters of the finished wine material are as follows: the volume fraction of ethyl alcohol (strength) is 12.3% vol. (fluctuating within 11.2–13.0% vol. depending on the year), the concentration of titratable acids is 5.5 g/dm³, volatile acids are 0.45 g/dm³, and the total content of sulfur dioxide (SO2) is 119.8 mg/dm³. The high tasting score of the finished wine, averaging 8.5 points according to the results of the profile committee, confirms the good potential of using this interspecific hybrid in modern winemaking.