Problems of potato seed in the Republic of Mordovia

Vegetable crops make up the bulk of the world's agricultural crops. Currently, the gross yield of vegetables in the world is 560-570 mln. tons, and in developed countries, per capita consumption of vegetables corresponds to 100 kilograms per year. From ancient times, one of the main conditions for ensuring high and quality yields of vegetable crops is the protection of crops from diseases. To meet the needs of the population and industry of the republic, about 1.9 mln. tons of potatoes and 5.9 mln. tons vegetable and melon products are required. In order to increase the yield and quality of vegetable crops grown in the country, the use of modern technology in their cultivation, the introduction of productive and local varieties, as well as a number of factors play a special role in effective protection of vegetables from various diseases. KEYWORDS: Alternaria, seed protectants, potato seed, tomato seed, disease, pathogen, seed infection.

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BIOLOGICAL JUSTIFICATION OF REDUCTION OF Y-VIRUS REINFECTION DURING REPRODUCTION OF SEED POTATO WITH A LOW DEGREE OF INFECTION

Vestnik of Kazan state agrarin university ◽

10.12737/2073-0462-2020-16-20 ◽

2020 ◽

Vol 15 (3) ◽

pp. 16-20

Author(s):

Faniya Zamalieva

Keyword(s):

Final Stage ◽

Planting Density ◽

Potato Seed ◽

Seed Potatoes ◽

Seed Material ◽

Low Degree ◽

Long Time ◽

Vector Activity ◽

Zero Values ◽

The Republic

The studies were carried out with the aim of biological substantiation of a decrease in Y-virus reinfection during the reproduction of seed potatoes with a low degree of infection. The experiments were carried out in 2001-2006 in Laishevskiy district of the Republic of Tatarstan. In 2001-2003 and 2002-2004 the total vector activity of aphids for three years was 393 and 310 equivalent units, respectively, the degree of infestation at the final stage reached 45.8 and 20.8%. In 2003-2005 and 2004-2006 the total vector activity of aphids for three years was higher than in previous cycles by 2.0 ... 2.5 times (785 and 610 equivalent units, respectively), but the degree of infestation at the final stage was only 4.1% and 1, 7%. For the first time, a calculation formula was obtained and the distances between diseased potato plants were specified, depending on the degree of contamination of the seed material. With a planting density of 55 thousand plants/ha, the formula takes the following form: , where у is the distance between infected plants, meter; х is the degree of infection with the virus (х > 0), %. The relationship between the degree of planting infestation and the distance between diseased plants is inversely proportional, graphically it is a hyperbole. The dynamics of changes in the distance between infected plants was traced with a decrease in infection from 100% to close to zero values. It was revealed that the 1% level of infection is critical. With an increase in infestation from 1 to 100%, the distance between diseased plants decreases from 4.26 to 0.42 m, which is a small distance for winged aphids to overcome. A decrease in infestation from 1% to close to zero value may lead to an increase in the distance between diseased plants from 4.26 m to theoretically infinite. Seed material, with close to zero infection, is safe to reproduce for a long time without the risk of rapid reinfection, due to the significant distance for vectors between sources of infection and a decrease in the participation of most aphids in the transmission of viruses. The results obtained formed the basis for the potato seed-growing system and the technology for protecting seed potatoes from reinfection with the Y-virus in the conditions of the Republic of Tatarstan

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Time and Latitude in South Africa

International Astronomical Union Colloquium ◽

10.1017/s0252921100026816 ◽

1972 ◽

Vol 1 ◽

pp. 27-38

Author(s):

J. Hers

Keyword(s):

South Africa ◽

Cape Town ◽

Astronomical Observations ◽

Royal Observatory ◽

The Republic ◽

Astronomical Determination ◽

Limited Accuracy ◽

Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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