Scientific Papers Series B Horticulture

Scientific Papers. Series B, Horticulture. Vol. LVII, 2013Print ISSN 2285-5653, CD-ROM ISSN 2285-5661, Online ISSN 2286-1580, ISSN-L 2285-5653AbstractWINTERING RESISTANCE OF ORNAMENTAL WOODY PLANTSIN CONTAINERIZED CULTUREIon ROCABotanical Garden (Institute) Academy of Sciences of Moldova,18 Padurii Street, MD 2002, Chisinau, Republic of MoldovaCorresponding author email: roscasilva@yahoo.comThe target of the experience consists in establishing the level critical temperatures and the mode preservation duringcold period of the year for the species and cultivars of conifers in containerized culture. Because of at the plants arefortified in container conditions, frequently occurs the phenomenon of spiraling root system, standing at the peripheryof the substrate, endangered by frost and, proceeding from the need of protection during the winter, we suggest thefollowing objectives: * the comparative comportment of the species and cultivars during the cold season, depending onthe way of storage; * the species and cultivars resistance at low temperatures, depending on the ecologicalrequirements of plants. For containerized culture of ornamental species and cultivars were established followingconservation cold season: V 1 – protected plants displayed in greenhouse; V 2 – protected plants and exposed outdoorbut covered with protective acrylic cloth; V 3 – plants unprotected and exposed outdoors throughout the cold period. Asa result of the study it was found that the species and cultivars of conifers remarked the highest coefficient – 100%resistance at low temperatures, where all three variants of wintering (V 1 , V 2 , V 3 ), at the end of the cold period the plantswere started in vegetation and there were no damages caused by the frost.Key words: resistance wintering, containerized culture, preservation variants and cultivars.INTRODUCTIONRoots of the plants in the open field areprotected from the soil mass and penetratesdeeper, thus preserving it from the excess ofhigh and reduced temperatures. At the fall offrost, the temperature sometimes decreasesmore than a few degrees below the criticalpoint, except the portion from the soil surface.Different behaviors have the plants roots incontainerized culture from the temperate andsub temperate zone, where the freezing point isnot lethal, comparatively with the temperatecontinentalclimate in the Republic of Moldova.In temperate zone, the aerial part of themajority of species possesses the ability ofincreasing their resistance to wintering, fromthe moment of reducing the duration of the dayand the decreasing of fall temperatures. On thecontrary, the containerized plant roots in localconditions have a reduced capacity forresistance to wintering or even are missing. Atthe plants grown in the cylindrical shapecontainers is often the phenomenon of spiralingof the roots, so the young roots are much more377vulnerable to the injuries caused by the lowtemperatures. In that case, the containerthickness of the wall performs the duties of theprotector of roots to lethal temperatures. If thetemperatures, fall below the critical point forsome time, the roots, coming in contact withthe interior surface of the container, freezes. Insuch cases, the roots regenerate from theremaining who survived inside the culturesubstrate and from the base of the plant.Therefore, if the temperature persists at orbelow the lethal point then the temperature ofthe culture substratum integral mass alsoreaches the lethal temperatures, thuscompletely destroying the root system. Thedegree of deterioration of the root system isdifficult to determine until start the vegetationseason and only when takes place thedesiccation we can establish the full effect ofthe damage state (Rosca, 2003). From atechnological point of view is recommendedthe transferring of suspicious moderatelyaffected plants in greenhouses heated (Gouin,1973; Rosca, 2003). More authors attest the