УДК 633.71

ЭФФЕКТИВНОСТЬ ДВУХ ЛАБОРАТОРНЫХ МЕТОДОВ ЗАРАЖЕНИЯ ТАБАКА ГРИБКОМ Р.ALTERNARIA

Георгиева-Андреева Мариела1, Танова Красимира2
1Институт земледелия, г.Шумен, Болгария, научный сотрудник
2Шуменский Университет «Епископ Константин Преславски», Болгария, доцент

Аннотация
Были испытаны три варианта заражения листьев табака: суспензией со спорами грибка р.Alternaria, агаровым блоком с верхней стороны листа и агаровым блоком с нижней стороны листа. На начальном этапе заражения более интенсивное развитие болезни установлено в пробах, зараженных агровым блоком с верхней стороны листа, а через 10 дней после инокуляции более уязвимыми оказались растения, обработанные споровой суспензией.Три исследованные метода искусственного заражения растений табака могут успешно использоваться на практике.

Ключевые слова: агаровый блок, искусственное заражение, споровая суспензия, табак


EFFICACY OF TWO LABORATORY EXPERIMENTS FOR INFECTING TOBACCO WITH FUNGUS OF ALTERNARIA GENUS

Georgieva-Andreeva Mariela1, Tanova Krasimira2
1Agricultural Institute, Shumen, Bulgaria, researcher
2Konstantin Preslavski University of Shumen, Bulgaria, Associate Professor

Abstract
We have tested three variants of infecting tobacco leaves with fungus of the Alternaria genus– with suspension of spores; with agar blocks, from the upper side of the leaf and with agar block, from the down side of the leaf.
In the initial stages of the infection process the most intensive development of the disease is established in the specimens with the agar block put on the upper side of the leaf and after the tenth day of the inoculation the strongest damage is observed with the leaves infected with the spore suspension.
The three observed experiments for artificial infection of tobacco leaves can be used successfully in practice.

Keywords: agar block, artificial inoculation, suspension of spores, tobacco


Рубрика: Биология

Библиографическая ссылка на статью:
Георгиева-Андреева М., Танова К. Efficacy of Two Laboratory Experiments for Infecting Tobacco with Fungus of Alternaria Genus // Исследования в области естественных наук. 2014. № 8 [Электронный ресурс]. URL: http://science.snauka.ru/2014/08/8301 (дата обращения: 08.05.2017).

During the recent years the brown spots on the tobacco leaves turn out to be a problem for the culture in definite tobacco producing regions in the country –Shumen, Gotse Delchev, Kardjali. The disease most often develops late during the vegetation period, around the ripening period and even after the harvest of the tobacco. When there is higher attack extent the spots merge and form wide burnt zones that make them useless for manipulation. Similar diseases can develop on the seed cases. Sometimes the tobacco leaf spots can also develop on the leaves of the Oriental tobacco on the strings or even on the whole plant cured tobacco sort Burley (Станчева, 2002, 50-79). According to Slavov and his team (2004, 85-89) the Alternaria fungus has unstable pathogenicity which is strongly influenced by the environment conditions. According to the authors there are different pathogenic types that differ by morphology, ability to sporulate and infect. The fungus crops pathogenicity proof isolated from infected plants can be seen by artificial infection (Stancheva, 2004, 398). The artificial infection of plants or plants’ parts in laboratory environment is a fast and cheap approach for estimating the stability (Гешеле,1978, 141-147).

The aim of the current research is comparison of the efficacy of three laboratory approaches for artificial infection of tobacco with pathogens from Alternaria genus.

Materials and Approaches

The experiment is conducted at the Agricultural Institute in Shumen. For the aim of the research we select tobacco leaves with symptoms of the disease, brown leaf spots, and from them we isolate Alternaria genus fungus. From the monospore cultures we plant petri dishes with potato-glucose agar and cultivated in thermostat with temperature of 250 C in darkness. From the obtained spores we prepare suspension and agar blocks with a diameter 80mm, inoculated with spores.  With the obtained materials we infect tobacco leaves and put them in humid cameras in thermostat for 10 days.

The experiment can be fulfilled in four variants:

-          With distilled water for the control sample.

-          With spore suspension.

-          With agar block from the upper side of the leaf.

-          With agar block from the bottom side of the leaf.

Every variant has ten repetitions (one leaf) and in every variant of the experiment we use identical quantity of inoculum. In the course of the experiment we execute three readings (spots size and grade) on the third, the seventh and the tenth day since the infection.

Results and Discussion 

On figure 1 we can see the damage growth intensity. The first reading (after the third day since the beginning of the experiment) shows that in all the variants with artificial inoculation the plant samples are infected and the damage growth intensity is considerably higher than the intensity in the control sample.

 

Figure 1.  Growth of the brown leaf spots

At the second reading (the seventh day) we observe considerable differences in the values read in the infected leaves. The strongest growth of the brown leaf spots is established in the specimens infected with agar block from the upper side of the leaf. The average diameter of the spots surpasses the average diameter of the spots in the control sample with 80%. Much lower result we can read at the infection with agar block from the lower side of the leaf (average diameter 3.4cm) and infection with suspension (1.7cm).

These results can be explained with the fact that in the case with the agar blocks we have developed mycelium while in the case with the spore suspension we need time for the spores to sprout and for the mycelium to be generated. The more intensive dissemination of the infection in the leaves infected with agar block from the upper side of the leaf in comparison to the variant with agar block put on the down side of the leaf can be explained with the characteristics of the agent. In natural conditions the pathogen penetrates in the leaves through the stomata.

On the 10-th day (fig.2) the strongest development can be observed on the leaves infected with spore suspension (average grade – 4.7). With the agar blocks the differences are insignificant-4.4 and respectively 4.5.

Figure 2.Variation of the attack degree of the variants in the experiment

Conclusions 

The three examined approaches of artificial infecting of tobacco leaves in humid camera can be used successfully in practice.

In the initial stages of the infection process the most intensive development of the disease brown leaf spots is established in the samples with agar block put on the upper side of the leaf.

After the tenth day of inoculation the strongest damage is observed with the leaves infected with spore suspension.


References
  1. Станчева Й. Атлас болезней сельскохозяйственных культур. Том 3. Болезни полевых культур.Пенсофт.София.198с. 2002.
  2. Slavov S., Mayama S., Atanassov A.Some Aspects of Epidemiology of Alternaria alternata Tobacco Pathotype. Biotechnology & Biotechnological Equipment.Vol. 18. No. 3. pp. 85-89. 2004.
  3. Станчева Й. Общая патология  растений. Пенсофт.София.534с. 2004.
  4. Гешеле Э.Э. Основы фитопатологической оценки в селекции растений. Москва. Колос. 208с. 1978.


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