Field experiments with early potatoes grown under polypropylene (PP) covers (Lytrasil Termoselect Ëxtra"and "Spanbond"- SUF-17) was carried pout during the period 2004 - 2006, at the Maritza Vegetable Crops Research Institute, Plovdiv. It was analysed the meteorological conditions during the vegetation period for the region of Plovdiv. The influence of PP covers on the early potatoes development was studied. It was established that potatoes accelerate their development as a result of higher temperatures in both polypropylene covers. It is expressed in the strongest way at the beginning of vegetation period. Large-scale tuber germination under PP covers occurs from 2 to 8 days earlier than in the control treatment (cover free). The following phenological phases (budding and flowering) under PP covers also occur earlier (from 2 to 4 days). It is observed that the effect of PP covers on the phenological development becomes smaller in warmer spring and with coming of the summer. The differences between the PP covered treatments and the control one decrease (1 - 2 days). It was established that both studied covers make plant development acceleration as well as protection of germinated plants, in the beginning of vegetation, from unfavorable effects of spring frost.
Fenological development of early potatoes under polypropylene fleece