FEATURES OF THE AGROTECHNOLOGY OF EARLY RIPE GRADES OF POTATOES AT CULTIVATION ON THE SEED PURPOSES IN CONDITIONS OF THE SMOLENSK REGION

The most significant in the technology of growing potatoes are the timing of removal of the tops, as this factor directly affects the physiological state of the tubers and their quality. Therefore, the aim of the study was to determine the effect of the timing of removal of tops on yield, quantitative yield and quality of elite seed of early maturing potato varieties Snegir, Delphin, Udacha and Zhukovskij rannij. Experience, observations and accounting were carried out according to generally accepted methods. The study was conducted in a field experiment of the Smolensk Institute of agriculture (ex. Smolensk GOSHOS). As a result of phenological observations, it was found that the mass flowering did not occur simultaneously in all studied potato varieties. Before all the phase of mass flowering occurred in the Zhukovskij rannij variety. The percentage of plant viral diseases in all studied varieties in the variant with the term of removal of the tops 21 days after mass flowering was higher, compared with the options for removing the tops in earlier flowering periods. The maximum yield of seed fraction of potato tubers in varieties Delphin and Snegir (12.6 and 26.1 t/ha, respectively) was noted in the version with the second term of removal of the tops, in varieties Zhukovskij rannij and Udacha (23.2 and 23.4 t/ha, respectively) – in the version with the term of removal of the tops 21 days after mass flowering. The yield of tubers seed fraction and their mass were the highest varieties of Dеlphin and Zhukovskij rannij. According to the results of the tuberous analysis, an increase in the total number of tubers affected by fungal diseases was observed in variants with later dates of removal of the tops. The most affected disease of all the studied varieties was the grade of bullfinch (1.5-4%), the most resistant to disease – cv. Udacha.