The resistance of 10 potato varieties to mechanical injury was tested. Large intra- and intervarietal variations were detected. The Dutch varieties, Record and Bintje, proved to be the most resistant followed by the Finnish varieties Jaakko and Pito. The amount of severe injuries increased with the age and the size of tubers. Among these varieties no correlation appeared between varietal starch content and injury resistance of tubers

Esko Seppänen

Agricultural and Food Science

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THE RESISTANCE OF TEN POTATO VARIETIESTO MECHANICAL INJURYEsko SeppänenDepartment of Plant Pathology, Agricultural Research CentreReceived March 7, 1972Abstract. The resistance of 10 potato varieties to mechanical injury was tested. Largeintra- and intcrvarietal variations were detected. The Dutch varieties, Record and Bintje,proved to be the most resistant followed by the Finnish varieties Jaakko and Pito. Theamount of severe injuries increased with the age and the size of tubers. Among these varietiesno correlation appeared between varietal starch content and injury resistance of tubers.Mechanical damage is a serious problem everywhere in the mechanized growing ofseed and table potatoes and has been widely studied. Several investigators have shownthat varieties vary considerably in resistance to mechanical injury (Lampe 1959, Robert-son 1966, Dambroth 1967, Gall et al 1967, Jacobsen 1969, Gechse 1970). In 1968 awork dealing with the injury resistance of varieties commonly grown in Finland wasstarted. This paper is the first report on that study.Materials and methodsIn 1968 nine varieties and in 1969 ten varieties were grown in sandy soil in each oftwo replicates. Fertilization each year was 50 kg N, 53 kg P and 125 kg K per hectare;pH of the soil was 6.2. The seed potatoes originated from the South Savo ExperimentStation and were planted in both of the years at the usual planting time, the end of May.In both years the weather during August was drier than normal and ripening of thecrops started by the latter half of August. Tubers were dug by hand.The starch contents of tubers and tuber size distribution of the varieties are presentedin Table 1. Because of the dry August the starch content was about 3 percentage unitshigher than usual. The tubers remained smaller than usual and only a few tubers wereheavier than 110 g. Also varietal differences in size distribution were rather small.To simulate mechanical injury to tubers during harvesting a simple apparatus usingthe pendulum principle was constructed. A weight of 1 kg with a cylindrical pin (0 8 mm)attached to it was fastened to the rim of a wheel. When the weight was released fromdifferent heights the rounded surface of the pin hit the tuber with a speed in accordance94Table 1. Earliness, starch content and size distribution of the tubers of the varieties studied.Variety Earliness Starch Percentage size distribution (by wt.)content% 21—50 g 51—80 g 81—110 g —llO gJaakko early 18.0 28 47 25 0Sieglinde „ 15.8 41 44 15 0Bintje early main crop 17.0 27 48 25 0Eigenheimer „ 19.7 37 45 18 0Amyla late main crop 20.1 34 45 21 0Olympia„ 15.9 43 41 15 IRealta „ 18.1 26 44 30 0Record „ 17.6 23 42 34 1Pito late 20.8 25 45 29 1Valtti „ 16.5 28 41 30 1with the equation; mass X acceleration X height (excluding friction). Three degrees ofspeed were used, 1.64, 1.80 and 2.00m/sec. The tuber was placed so that the pin hithalfway between the stem and bud ends. To imitate the action of a harvester the tuberwas allowed to move freely by the force of the hit.The tubers so treated were examined 2 to 3 months later. They were weighed individ-ually and halved through the point treated. Injuries were classified according to theirdepth: slight (< 2 mm), moderate (2 to 5 mm) and severe (> 5 mm). The methodused is quick and suitable for comparison of varieties.In the calculation ofresults, tubers analyzed were divided into three size classes, 21to 50 g, 51 to 80 g and 81 to 110 g. The means ofclasses were calculated taking into con-sideration the weights of tubers. In statistical analysis, Eigenheimer was used as a standardand the deviations of values for other varieties from values for Eigenheimer were testedusing the t-test.Results and conclusionsPreliminary tests were carried out in 1968 with 9 varieties. The numbers of tubersin each size class tested at each degree of speed were only 40. The intra-varietal variationwas large and therefore the numbers of tubers sampled were insufficient for meaningfulstatistical analysis. The results obtained, however, were fairly similar to those obtainedin 1969 (Fig. 1). The only striking difference was the relationships of the injury resistanceof Pito to those of Record, Bintje and Jaakko in the two years.In 1969 10 varieties were tested at 3 different times. The first injury tests were con-ducted on Aug. 14th, the second on Aug. 28th (at the beginning of normal harvest time),and the third after storage to March 14th. The storage temperature was 5° C. All treat-ments were carried out at a temperature of 20° C.In spite of large variations within varieties (cf. Lampe 1959), significant differencesbetween varieties as well as between treatment times were established. In general, theinjury-resistance of the varieties decreased with aging of tubers; slight injuries decreasedbut severe ones increased (Fig. 1). The resistance of the varieties was not correlated withtheir earliness nor with the starch content of their tubers (Table 1 and Fig. 1).Fig. 1. Percentages of slight, moderate,and severe damage to different varietiesin a preliminary test in 1968 and afterapplication of injury treatments on threedates (Aug. 14, Aug. 28 and March 14)in 1969—70. Means were calculatedaritmethmetically from size class injurymeans.Kuva I. Lievien, kohtalaisten ja pahojen vioi-tusten prosenttiset osuudet eri lajikkeiden muku-loissa valmistavassa kokeessa v. 1968 sekä kol-messa eri käsittelyssä {l4. 8., 28. 8. ja 14. 3.)v. 1969— 70. Tulokset ovat kolmen iskuno-peuden ja kolmen suuruusluokan keskiarvoja.9596Considering the severity of defects and all three times of treatment, the injury resistanceof Record, Bintje, Jaakko and Pito was significantly higher than that of Eigenheimer andthe other varieties. The resistance of Realta was significantly lower than that of Eigen-heimer. The rapid decrease in injury resistance in Pito and Eigenheimer with tubermaturity and in storage is striking and requires further examination.The present results are similar to the findings of other workers. The high resistance ofRecord has been reported by Robertson (1966) and that ofBintje by Dambroth (1967),Gall et al (1967) and Gechse (1970). According to Jacobsen (1969) the injury resistanceof Bintje is only moderate. The susceptibility to injury of Sieglinde has been previouslyreported by Lampe (1959), Dambroth (1967) and Jacobsen (1969). According to Dam-broth (1967) Amyla and Olympia are more injury-resistant than Sieglinde but this isnot corroborated by the results of the present tests.The relation of tuber size to injury is shown in Fig. 2 in which all varieties have beenaveraged. Large tubers were more susceptible to injury than smaller ones (cf. Lööw1960). Varieties, such as Record, which have a higher percentage of large tubers willtend to be more susceptible to mechanical injury than smalltubered varieties. This is notindicated in Fig. 1 because the injury values shown are arithmetic means of the averageinjury of the three tuber-size classes used and thus do not take into consideration thepercentage of tubers in each size class.Fig. 2. Percentage distribution of slight, moderate and severe damage totubers of different size classes and different treatment times. Means ofaverages of 10 varieties.Kuva 2. Lievien, kohtalaisten ja pahojen vioitusten prosenttiset osuudet eri kokoluokissa ja erikäsittelyissä; tulokset ovat 10 lajikkeen keskiarvoja. ( Treatment = käsittely, undamaged = vioil-tumattomat).97REFERENCESDambroth, M. 1967. Der Einfluss von Umwelt und pflanzenbaulichen Massnahmen auf die spezifischcVViderstandsfähigkeit von Kartoffelknollen gegen mechanische Belastungen. Diss. 149 p. Giessen.Gall, H. & Lambrecht, P. & Fechter, E. 1967. Erste Ergebnisse mit dem Rilckschlagpendel zurBestimmung der Beschädigungsempfindlichkeit von Kartoffelknollen. Eur. Potato J. 10: 272 —285.Gechse, M. 1970. Chemish-analytische und histologische Untersuchungen iiber die Ursacher der Beschä-digungsemphndlichkeit der Kartoffel. Diss. 76 p. Gottingen.Jacobsen, B. 1969. Further investigations on tuber damage resistance of different potato varieties. Proc.4th Trienn. Conf. EAPR, Brest: 242 —243.Lampe, K. 1959. Entwicklung und Erprobung einer Methode zur Bestimmung der VViderstandsfähigkeitvon Kartoffelknollen gegen Beschädigungcn. Diss. 125 p. Bonn.Lööw, H. 1960. Beurteilung von Beschädigungcn an Kartoffelknollen. Kann man nur eine Grössen-fraktion beurteilen und dadurch die Beurteilung vereinfachen? Eur. Potato J. 3: 283—295.Robertson, I. M. 1966. Effect of season and variety on the susceptibility of potato tuber to damage.Proc. 3rd Trienn. Conf. EAPR, Zurich: 266—267.SELOSTUSPERUNALAJIKKEIDEMME KÄSITTELYNKESTÄVYYDESTÄEsko SeppänenKasvitautien tutkimuslaitos, Maatalouden tutkimuskeskusKymmenen meillä yleisesti viljellyn perunalajikkeen käsittelynkestävyyttä tutkittiin yksinkertaisenheiluriperiaattelle konstruoidun laitteen avulla. Alustava koe tehtiin v. 1968 ja varsinainen 3 käsittely-aikaa käsittävä tutkimus v. 1969—70. Käsiteltävät mukulat oli kasvatettu yhdenmukaisesti kahtena ker-ranteena, nostettu hellävaraisesti ja käsitelty samassa lämpötilassa. Kolmea iskunopeutta (1.64, 1.80 ja2.00 m/sek.) käytettiin. Mukulat punnittiin ja analysoitiin yksitellen. Näin ollen tulokset oli mahdollistalaskea kussakin kokoluokassa painotettuina keskiarvoina. Esitetyissä tuloksissa (kuva 1) on kunkin lajik-keen mukulakokojakautuma eliminoitu, minkä vuoksi suurimukulainen lajike, kuten esim. Rekord onalttiimpi kuin mitä tulokset osoittavat.Sekä lajikkeiden sisäinen että välinen vaihtelu oli suuri. Lisäksi oli todettavissa, että pahojen vioitusten(yli 5 mm) osuus suureni mukuloiden iän ja painon lisääntyessä. Ottaen huomioon kaikki kuvassa 1 esi-tetyt tulokset ovat Record ja Bintje kestävimmät, seuraavina ovat Jaakko ja Pito. Ero näiden neljän jamuiden lajikkeiden välillä oli merkitsevä. Eigenheimer, Amyla ja Siikli (Sieglinde) olivat suunnilleen yhtäkestäviä, Olympia, Valtti ja Realta niitä alttiimpia. Yllättävää on Pidon ja Eigenheimerin alttiuden suurilisääntyminen varastoinnin aikana.Saadut tulokset ovat melko yhtäpitävät ulkomaisten tutkimusten kanssa, joissa Bintje ja Rekord ontodettu kestäviksi sekä Amyla, Olympia ja Siikli alttiiksi.

The resistance of ten potato varieties to mechanical injury

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The resistance of ten potato varieties to mechanical injury

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