Factors Affecting Flower Abortion and Malformation in Roses

Abstract

The formation of blind shoots and malformed flowers in rose plants grown under various temperatures and light intensities, and subjected to different cut back procedures has been studied. Low temperature, low light intensity and low cut back promoted blind shoot formation. Hybrid tea cultivars are more sensitive for unfavourable temperature, light and cut back treatments than Floribunda cultivars. The process of floral abortion is initiated during the early stages of shoot growth before the differentiation of floral parts has been completed. Low temperatures (12–15°C) in this critical stage of development strongly promote blind shoot formation, but have no effect when stamen and pistil primordia had been formed in the apical flower bud. The formation of malformed flowers, so‐called “bullheads”, which have significantly more petals than normal flowers, is also promoted by low temperature and low cut back. Light intensity seems to have no effect. Shoots subjected to low temperature (12°C) during the early stages of development, before the differentiation of the floral organs are fully completed, produce malformed flowers to a greater extent than shoots subjected to high temperature (18–24°C) during this period. It is suggested that blind shoot formation in roses is subject to hormonal control.

Flower Bud Atrophy in Baccara Roses

“…The GA content is generally lower in shoots which developed from the second bud than in the upper one, similar to the more frequent occurrence of "blindness" in the second shoot (Figures 1-3), Furthermore, external application of GA to the growing apices under conditions which encourage fiower atrophy considerably reduced the extent of atrophy (Zieslin and Halevy 1976b, Table 1). The effect of removal of young leaves on flower bud atrophy (Zieslin and Halevy 1976a) can also be attributed to the fact that these leaves serve as a source of GA (Humphries andWheeler 1963, Sheldrake 1973), Flower atrophy in roses occurs almost invariably during the early stages of the fiower's development, before development of the anthers and the pistils (Moe 1971), This may be due to the fact that these organs serve as a source for GA synthesis, so that after their development the fiower is independent of the other plant parts for the supply of this hormone. The mode of GA activity in preventing fiower atrophy is unclear.…”

Produção e qualidade de botões de rosa c v. Vega cultivados sob plásticos de cobertura com diferentes anos de uso

“…Como não houve diferença entre os anos de uso, significa que os plásticos continuaram a deixar passar a radiação. Moe (1971) concluiu que a temperatura constante por mais de 21 dias favorece a manutenção dos botões florais( não ocorrência de abortos) indicando a importância da manutenção da temperatura interna estável proporcionada pela cobertura plástica. Tabela 3 -Valores médios do diâmetro do botão floral (cm), para as diversas datas e nos diversos tratamentos estudados.…”

Evapotranspiration of rose cultivated in protected environment

“…Com isto, a planta reduz sua capacidade de fornecer hastes florais de valor comercial devido à diminuição da produtividade da cultura (Mastalerz, 1987;Moe, 1971). De acordo com Bañon Arias et al (1993) a umidade relativa do ar ideal para a cultura da roseira está entre 70 e 75% sendo que para o período de brotação das gemas e crescimento dos brotos é aconselhável uma faixa entre 80 e 90%.…”