CALIFORNIA AGRICULTURAL EXPERIMENT STATION and DELIGH Two New Early Maturing U: MAY, 1948 BULLETIN 705 THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA • BERKELEY Pet/ette and delight are much like Thompson Seedless, but mature earlier and appear to show promise in regions where early maturity is of first importance • The grape-breeding program of the University of California was begun in 1929 by the Division of Viticulture. Originating new varieties better adapted to California conditions is one of the main purposes of this program. During the ten-year period 1931-1940, a total of 23,658 seedling vines of controlled parentage were planted in the vineyard for fruiting. From these, promising vines are being selected for further tests in trial plots widely scattered throughout California. In some instances, semicommercial trials of the first selections have already been completed. This is true of PERLETTE and DELIGHT. • Cuttings of these varieties are not offered for sale or distribution by the University of California, but may be purchased from nursery- men. If you want to know where they may be obtained, write to the Division of Viticulture, California Agricultural Experiment Station, Davis, California. Perlette, approximately Vi natural size PERLETTE AND DELIGHT Two New Early Maturing Seedless Table Grape Varieties H. P. OLMO Associate Professor of Viticulture and Associate Viticulturist in the Experiment Station Seedlessness in table varieties has been emphasized in the grape-breeding project. The great success of Thompson Seedless as a table fruit amply proves that the con- sumer is willing to forego large fruit size, flavor, and attractive color if he can eat the whole berry without the bother of seeds. Perlette and Delight are the first new seedless varieties of a series now under test at Davis. PERLETTE is a hybrid of Scolokertek hiralynoje 26 x Sultanina marble, station seedling 1253F21, from a cross made in 1936. The seed was planted in the fall of 1936, and the vine first fruited in 1940. Scolokertek hiralynoje 26 was introduced from Hungary in 1934 as P.I. 103996 through the cooperation of the United States Department of Agriculture. The Sultanina marble was received by the California Experiment Station in 1933 as an inadvertent mixture among a collec- tion of Russian varieties, under P.I. 98388. Because the translucence of the mature fruit is its most striking feature, a name describing this characteristic was sought. The name "Pearl" was suggested, but it had already been used for another grape variety. The French name Perlette, sig- nifying "little pearl" was selected. Perl- ette seems to have a definite place in the variety picture because it is the earliest maturing seedless variety in existence. The fruit is unique in that its beautv sur- Received for publication January 22, 1948. passes other early varieties, and the ap- pearance of delicacy is maintained for a considerable period after harvest. This is in contrast with other varieties such as the Pearl of Csaba and Chasselas dore which quickly deteriorate in appearance and quality. DELIGHT, station seedling 1220F21, is a sister seedling of Perlette. The cross was made in 1936, and the vine first fruited in 1940. This variety was marked for observation from the first season of fruiting, because of its early maturity and the characteristic Muscatlike flavor in- herited from its Hungarian parent. The initial test plot at Davis consists of 12 vines of each variety along with a check plot of Thompson Seedless. All of the vines were budded on rootstock 3309 in September, 1941. The vines were trained on a low wire trellis as bilateral horizontal cordons. At pruning time, from 8 to 14 spurs of 2 buds each were left, depending on the vigor of the vine. Otherwise, all vines were treated alike. Yield records have been taken annually since the second year of bearing, that is, 1944. The data are presented in table 1. Delight is less vigorous than either Perlette or Thompson Seedless, although to date its capacity for production is not significantly different from that of Thompson Seedless in the same plot. Perl- ette has remained very vigorous, despite a heavy annual yield during the past three seasons. [4 TABLE 1 | PERLETTE AND DELIGHT COMPARED WITH THOMPSON SEEDLESS, * DAVIS PLOT ^\XXXXX\XXXX\XXXXXXXX>K*VC%X»$»>AV<SN\N '-.\\ XXX XXV x ^ kX\\\\\X\\\\\\V\\»\\\\\\\VX\»VA%VA%>¥k\V»V«» , W«W \ _ __ . j _>. M -M — » - — ^ . O | Vigor of Vine J 1 | Palatability pyly 31, 1942 | Uepf. 1, 1945 I ! ^ \Au B . 1, 1946 | July 24, 1947 ^kVVXXXX^V.XVCXXXXVXVCV^^ [5] Cane pruning not needed for Perlette and Delight Perlette is a very productive variety, yielding about twice as much as the Thompson. The range in yield for the experimental vines in the fifth bearing year (1947) was from 44.7 to 83.3 pounds per vine. The yield of the Thomp- son Seedless plot, used for comparison, was undoubtedly smaller than if the standard cane pruning had been em- ployed instead of the cordon short-spur system. Delight is less fruitful than Perl- ette, but the average yields at Davis for the four-year period are not significantly different from those of Thompson Seed- less. Since the cordon system of pruning has the advantages of producing better fruit quality, and being more economical, these new varieties are superior in this respect. Cane pruning of Perlette and De- light appears neither necessary nor de- sirable. Berries of new varieties larger than the Thompson Both Perlette and Delight have con- sistently produced larger berries than Thompson Seedless. Perlette is about 1/3 larger by weight; Delight about 1/10 larger (table 1). The rudimentary seed development in both varieties is similar canes or trunks to increase berry size has given percentage increases comparable to Thompson Seedless. Girdling of the with the Thompson. Some growers be- lieve Perlette would yield a berry of the same size as girdled Thompson Seedless if properly berry-thinned without gir- dling. Both new varieties mature earlier than Thompson Seedless. This should be of dis- tinct advantage in those districts produc- ing table fruit for early shipment, such as the Coachella and Imperial valleys of California and the Salt River Valley of Arizona. In the cooler coastal areas, such as Napa and Oakville, Thompson Seed- less usually does not reach maturity, and the berries remain very small. In these same areas both Perlette and Delight pro- duce fruit of good quality and of normal berry size. At Davis, selected clusters of Perlette have been palatable about August 1, those of Delight about August 6, and those of Thompson Seedless about August 18. Table 1 includes a comparison of matu- rity. Perlette ripens earliest and is mature and palatable at a very low sugar content, a characteristic of many varieties that ripen very early. Clusters of 13 Balling or above were palatable in the 1946 season, while Thompson Seedless at the same Balling, harvested on the same date, was hard, inedible, and had over double the acidity (grams per 100 cc of juice, as tartaric). At 18 Balling Perlette is actu- ally overripe, and, even though left on the vine for a prolonged period, the sugar concentration remains low. The palat- ability of even the best fruit is definitely inferior to the mature Thompson Seed- less; therefore, Perlette could not well compete with Thompson Seedless as table fruit if both were available at the same season. In taste, Perlette has usually been scored as neutral, but some samplers dis- tinguish a mild flavor that is characteris- tic of its Hungarian parent. Majority of tasters prefer Delight to the Thompson At Davis, Delight matures from 12 to 14 days in advance of Thompson Seed- less. The low acidity of Delight is one factor that enables it to reach a palatable stage sooner than Thompson Seedless. Unlike Perlette, the fruit sweetens almost as well as Thompson Seedless, in fact, at prime maturity many people prefer it to the Thompson. At Davis, the fruit loses palatability when the acidity goes below 0.5 and when overripe there is a tendency toward astringency. At prime maturity, Delight has a mild Muscat flavor, but un- fortunately this is extremely variable, even between clusters on the same vine. Nonetheless, the flavor is preferred by [6] the majority of tasters to that of the more neutral Thompson Seedless. Both varieties prove superior in commercial canning tests Perlette perhaps cannot be profitable for raisins, because of its overly compact clusters. In some seasons this condition may rupture the berries in the interior of the cluster and cause considerable loss from black mold. Raisin samples judged by an impartial jury indicate that the raisins of Perlette closely resemble those of Seedless Sultana and would be classed in this category. The raisins lack meati- ness and are low in sugar content. Raisin tests of Delight were conducted at Davis for three seasons with the prod- ucts judged by number. For comparison, Thompson Seedless was included as a numbered sample. Delight was rated superior or equal to Thompson Seedless. None of the five judges was able to detect the new variety, but accepted it as a selected sample of Thompson Seedless. Both new varieties, on the basis of small-lot tests, appear to be better adapted for shipping and handling as table fruit than Thompson Seedless. Delight has a much firmer and more resistant berry, with practically no shattering. The fruit holds for a long time, either on the vine or in storage. Perlette does not show the brown discoloration after handling so characteristic of very early varieties. No large-scale shipping tests of either variety have yet been made to eastern markets. Thompson Seedless is being used to an increasing extent for canned fruit salad and fruit cocktail mix. Canners have had poor results with the variety, largely be- cause the stems do not come off the ber- ries easily. The berries split and do not retain a good color during processing. Both Perlette and Delight have been con- sistently superior to Thompson Seedless in canning tests conducted in 1946 and 1947 with three commercial canneries. DESCRIPTION OF THE VARIETIES PERLETTE Vine: Develops slowly in juvenile stage, tending toward brachytic growth, be- coming less so with age. Buds out 8 to 12 days earlier than Thompson Seed- less; about the same resistance to pow- dery mildew as Thompson Seedless. Fruit well covered with heavy foliage canopy. Shoots: Tips strongly recurved; newly unfolding leaves bronzed; light, bright green ; glabrous, thick, with very prom- inent primary nervation. Canes: Wood brittle, maturing very early in the season; thick at base, tapering rapidly; light brown; striations few and not marked; internodes short, tending to be offset, giving the cane a zigzagged outline; buds very large, flattened, almost circular in basal sec- tion; outermost scales often mucronate and recurved at bud apices, lateral buds absent. Leaves : Large, with lateral sinuses poorly marked or reduced to a narrow slit: blade slightly undulated, glabrous on both surfaces, dark green, without lus- ter when mature, thicker and more leathery in texture than Thompson Seedless. Petiole often suffused with pink. Teeth few in number, very large, obtuse, pointed. Flowers: Large; calyptras large, elon- gated, shedding readily and completely : filaments long, pollen abundant and very fertile; ovary very small, very slender. Fruit: Cluster large, 450 to 700 gm; com- pact to very compact, peduncle lig- nified, thick, strong, 3 to 4 cm long. [7] Pedicels of the berries slender, smooth, very light in color, not much flanged at the point of attachment; adherence much better than Thompson Seedless and less shattering. Berries spherical to slightly ellipsoidal, one-third larger than Thompson Seedless, uniform in shape, bloom abundant, surface waxy in appearance, white with little chloro- phyll remaining at maturity, very dec- orative and of unique color. Skin very thin, very tender ; flesh firm, crisp, and juicy, flavor unique. Seeds rudimen- tary, never becoming flinty, equal or smaller in size than those of Thompson Seedless. Sugar content low, 13 per cent to 17 per cent by Balling hydrom- eter, acidity as tartaric 0.48 to 0.75 gm per 100 cc of juice (at Davis, Califor- nia). Palatability only fair. Palatable 14 to 20 days in advance of Thompson Seedless. Unlike many early white vari- eties, the fruit does not discolor from bruises on handling. Keeps, stores well. DELIGHT Vine: Somewhat less vigorous than Thompson Seedless; as a young vine rather slow to become established and difficult to train to a head because of irregular growth and branching; some fruit exposed by poor foliage cover. Trunk thick, short-noded. Budding out 6 to 8 days earlier than Thompson Seedless. Shoots: Of the same color and aspect as Thompson Seedless, but more leafy and the expanding leaves more deeply bronzed. Canes: Short, few in number, arching and procumbent, with short internodes and highly swollen nodes, tending to have irregular outline; buds very large and flattened. Leaves: Large, more entire and thicker than Thompson Seedless, with sinuses less developed, glabrous, dark green, blade slightly undulated, teeth very large, angular, obtuse. Flowers: Large, calyptras shedding com- pletely, filaments long, pollen abundant and highly fertile; ovary very small, slender. Fruit: Cluster large, conical, with heavy shoulders, 400 to 600 gm, well filled to compact; peduncle lignified and brown, very thick and woody, rigid, strongly branched, 4 to 5 cm long. Pedi- cels rather short, thick; brush long; adherence very good, even when over- ripe. Berries ovoid, slightly larger than Thompson Seedless, uniform in size, dark greenish yellow and easily identi- fied by the scattered, very prominent lenticels; skin thick and resistant to injury; flesh firmer than Thompson Seedless; flavor distinct and resem- bling Muscat, but variable in intensity. Sugar content high, 21 to 24 per cent; acidity low, 0.52 to 0.56, and declining very rapidly when overripe. Palatable about 10 to 12 days in advance of Thompson Seedless. Quality excellent when harvested at the best stage of ma- turity, but somewhat astringent and lacking acidity later in the season. ACKNOWLEDGMENTS I wish to thank my colleagues in the Division of Viticulture for their helpful observations and comments on these va- rieties. Many grape growers, processors, and vintners also have generously coop- erated in testing new varieties. Canning tests of the new seedless vari- eties were arranged by Mr. P. D. Caldis of the California Packing Corporation, San Francisco; Mr. Lee Richards of the Bercut-Richards Company, Sacramento; and the Pacific Grape Products Company, Modesto. For judging and classifying the raisin samples I am indebted to Mr. Charles Fisher of the Dried Fruit Association of California and five of his colleagues who provided such expert opinion in this field. 15w-5,'48(A7968s)