The Effect of Temperature, Potato Varieties, and the Origin of Cyst on the Reproductive Biology of Globodera Rostochiensis

Potato cyst nematode (Globodera rostochiensis [Wollenweber] Behrens) is a nematode species of worldwide regulatory concern. This nematode caused serious economic of potato losses in Indonesia. This research studied by factorial designed to evaluated the effect of temperature (10, 20, and 30ºC), potato varieties (`Granola´, `Margahayu´, and `Cipanas´), and origin of cyst (West, Central, and East Java) on reproductive biology of G. rostochiensis in the growth chamber. The research was conducted by observed of produced the new cyst number, reproduction fitness, survival, fecundity, and multiplication of G. rostochiensis. The result showed that all of the potato varieties were infected by G. rostochiensis when they were grown at the temperature ranging of 20 and 30ºC but not at 10ºC. The optimum temperature for maximum number of cysts with the highest reproduction factor, survival, fecundity and multiplication rate for all populations was 20ºC. The origin of cyst did not have any effect on the reproductive rate. The temperature of 20ºC provided is best environment for the life of G. rostochiensis on Granola. INTISARINematoda sista kentang (Globodera rostochiensis [Wollenweber] Behrens) adalah spesies nematoda yang mendapatkan perhatian khusus di seluruh dunia. G. rostochiensis menyebabkan kerugian ekonomi yang serius pada pertanaman kentang di Indonesia. Penelitian ini menguji pengaruh perbedaan suhu (10, 20, dan 30ºC), varietas kentang (Granola, Cipanas, dan Margahayu), dan asal sista (Jawa Barat, Jawa Tengah, dan Jawa Timur) terhadap biologi reproduksi G. rostochiensis di growth chamber menggunakan rancangan acak lengkap faktorial. Pengamatan dilakukan terhadap jumlah sista baru, kemampuan reproduksi, daya tahan hidup, keperidian dan multiplikasi G. rostochiensis. Seluruh varietas kentang yang diuji terserang G. rostochiensis pada suhu 20 dan 30ºC kecuali pada suhu 10ºC. Kisaran suhu optimum untuk memperoleh jumlah sista baru yang maksimum dengan kemampuan reproduksi, daya tahan hidup, keperidian dan multiplikasi untuk semua populasi adalah 20ºC. Asal sista tidak berpengaruh terhadap biologi reproduksi yang diteliti. Kentang varietas Granola yang ditanam pada suhu 20ºC merupakan inang yang sesuai untuk kehidupan G. rostochiensis.


INTRODUCTION
Potato cyst nematode (Globodera rostochiensis [Wollenweber] Behrens) is the most destructive nematode around the world (Marks & Rojancovski, 1998;Hodda & Cook, 2009), and is broadly distributed in tropical and subtropical regions. As the distribution of seed expands, the distribution of G. rostochiensis could expands as well. In Indonesia, G. rostochiensis was identified for the first time in the potato-growing area in Malang, East Java, in March 2003 .
G. rostochiensis damages potato plantation, thus contributing to low yields and limit the choice of potato cultivars (Oerke, 2006). The most potato varieties planted in Indonesia was Granola, although the Indonesian Vegetables Research Institute (IVegRI) have developed and released two varieties Cipanas and Margahayu. Cipanas is susceptible to Meloidogyne sp. (Anonymous, 1980) and Margahayu is well adapted in the highlands with altitude of 1.000−2.000 m above sea level (Anonymous, 2008).
Understanding the response of variety and local environment to G. rostochiensis are essential in developing the management of this nematode. The effects of temperature on embryonic development may comprise an important factor in the ecology and distribution of nematode. This temperature could be an important factor in the overall fitness of the nematode and its ability to extend its distribution range (Noe & Sikora, 1995). Soil temperature during the growing season affected the initial energy reserves of G. rostochiensis larvae. Relationships between soil temperatures and the G. rostochiensis biology and population multiplication were investigated to understand the risks of potato to be attacked by G. rostochiensis in relation to increasing soil temperatures associated with climate change, and to support the development of management model of G. rostochiensis. The objectives of this research were to determine the effect of temperature, potato varieties and the origin of cyst on reproductive biology of G. rostochiensis.

Experimental Design
The experiment employed a completely randomized factorial design with three factors and five replications. The first factor was the temperature consisting of three temperatures 10, 20, and 30ºC. The second factor was the origin of G. rostochiensis cyst, from Pangalengan (West Java), Wonosobo (Central Java), and Malang (East Java). The third factor was potato varieties, i.e. Granola, Cipanas, and Margahayu.

Potato Planting and Infestation of G. rostochiensis Cyst
Pots (13 cm diameter and 11 cm deep) were filled with a fine steam sterilized soil (particle size of 100−400µm) and sterilized manure with a ratio of 2:1 (w:w). Twenty cyst was put in muslin bags from each population (Pangalengan, Wonosobo, and Malang). Shoot of potato seed (Granola, Cipanas, and Margahayu) and cysts were placed in soil (Salazar & Ritter, 1993). After planting, the pots were placed in growth chambers in the laboratory of Center for Diagnostic Standard of Agricultural Quarantine, from September 2014 to August 2015. A thermocouple was placed in the growth chambers and the maximum-minimum temperatures were measured daily. The temperature regimes were 10, 20, and 30ºC with relative humidity of 80%. The light in the growth chamber was set with the illumination intensity of 3.400 lux, 12:12 (L:D) cycle. The plants were watered twice a day. In addition, the plants were fertilized according to the field recommendation.

Reproductive Biology of Cysts
The crops harvested at 85 days after planting. The soil was removed from each pot, placed in a plastic tray and then all dried at the temperatures of 22ºC (Tiliikalla, 1992). The roots were carefully washed to remove soil particles. Soil extraction to collect cysts was carried out according to Beaker method (Turner & Evans, 1998).
Observation was conducted by counting cyst number (the number of cysts found outside the muslin bag), reproduction fitness (number of cysts at the end of the study/number of cysts were inoculated), survival (number of cysts developed/ number of eggs added originally), fecundity (eggs/ new cyst), and multiplication (survival × fecundity).

Data Analysis
Analysis of variance (ANOVA) was conducted using SAS Program and mean differences were analyzed using Duncant Multiple Range Test (DMRT) at α = 5% if F test showed significance.

RESULTS AND DISCUSSION
The result showed that development of G. rostochiensis was influenced by the temperature and potato variety (Table 1−5). The cysts did not grow on potato planted in low temperature (10ºC). The interaction between temperature of 20ºC and potato variety significantly affected the biological development of G. rostochiensis, such as the number of new cysts, reproduction fitness, survival and multiplication of G. rostochiensis (P <0.05). On the other hand, high temperature (30ºC) did not interact with potato varieties. The development of G. rostochiensis was significantly better at 20ºC on all tested potato varieties than at 30ºC. The best development for G. rostochiensis was observed when this nematode attacked in Granola at the temperature of 20ºC. In contrast, Means followed by same letter are not significantly different. G. rostochiensis had the lowest biological development on Cipanas variety at 20ºC. Granola, Margahayu, and Cipanas were susceptible potato variety to G. rostochiensis. However, G. rostochiensis could not grow in the susceptible potato variety with unfavorable temperature (10ºC). In addition, there was a growth inhibition when G. rostochiensis reared in susceptible variety with high temperature (30ºC). The origin of the cysts did not affect the development of G. rostochiensis. The cyst from West, Central, and East Java produced no significant differences on the development of G. rostochiensis.
This research showed that G. rostochiensis could not grow on the soil with temperature of 10ºC, indicated that G. rostochiensis was not tolerant to low temperatures. Unfavorable environment (low temperature) trigger the dormancy of G. rostochiensis. In Finland, G. rostochiensis eggs could not hatch at 9ºC (Mulder, 1988). Eggs within the cyst will undergo diapause at temperatures less than 5ºC (Salazar & Ritter, 1993). Furthermore, G. rostochiensis developed at 20 and 30ºC in Granola, Cipanas, and Margahayu, although they grew better at 20ºC. These findings were similar with the previous research which showed that G. rostochiensis grew well in potato at ± 20ºC, and the cysts survived in the soil for one year (Ingham et al.,2015;Kaczmarek et al., 2014;Rinus, 2014;Lisnawita, 2007;Mulyadi et al., 2004).
All tested varieties were susceptible to G. rostochiensis because the population of cyst was > 100 cysts/plant/pot (Sysoeva et al., 2011). Furthermore, the best temperature for this nematode was 20ºC. Therefore, combination of susceptible potato and suitable temperature have better control at the spread of G. rostochiensis. Although at 30ºC this nematode did not grow as good as at 20ºC, they were still able to reproduce. Nematode development at a high temperature (30ºC) is limited by the inability of the host plant to provide adequate nutrition for the development of G. rostochiensis because of the growth of the host plant was not Means followed by same letter are not significantly different.

Varieties
Temperature ( (Kaczmarek et al., 2014). In Southern Italy, second stage larva of G. rostochiensis decreased drastically invasion into the roots at a temperature of more than 25ºC and 95% reduction occurred in a population of G. rostochiensis at temperature more than 30ºC (Bacic et al., 2011;Bridge & Starr, 2010;Turner & Evans, 1998). This suggests that increasing temperature due to external factors may be coped by the adaptability of this nematode. If this happens, more serious damage of potato by this nematode is predicted in the future.

CONCLUSION
Globodera rostochiensis grew well in all tested varieties (Granola, Cipanas, and Margahayu) when they lived at the temperature 20 and 30ºC. Temperature of 20ºC provided the better environment than 30ºC. Granola grown at 20ºC was the best host for G. rostochiensis.