ISHS Acta Horticulturae 533: VIII International Symposium on Timing Field Production in Vegetable Crops
SOWING TIMES AND ONTOGENETIC CYCLE IN TWO EARLY CULTIVARS OF CIMA DI RAPA (BRASSICA RAPA L.) |
| Authors: | I. Morone Fortunato, G. Damato |
| Keywords: | premature flowering, early flowering, apex organisation |
| Abstract:
In this paper we report a research work on early flowering of two cultivars of cima di rapa by studying their ontogenetic cycle. The study was divided into two phases. In this first phase, the stage of apex organization during ontogenesis has been defined. This phase clarified the similarity of Brassica rapa L. with long day plants and the difference with B. campestris L. In the second phase, the ontogenesis of two cultivars has been studied by istological observation in relation to the sowing dates over two years. Sampling of seedling began 15 days after sowing (DAS) and then every 5 days until apex differentiation. For the first and second sowing dates, apex differentiation occurred at the same time in ‘Quarantina’ (QR). Apex transition occurred 34–37 DAS, and differentiation 46–47 DAS. Inflorescence were harvested starting from 55–65 DAS for 15–16 days. For the third sowing date, temperature was lower and apex transition occurred 55 DAS and ended 30 d afterwards. ‘Sessantina’ (SS) resulted to be more sensitive to temperature than ‘QR’. The length of vegetative stage was 30, 45 and 55 d for the first, second and third sowing dates, respectively, and the length of transition was 16, 18 and 32 d. ‘SS’ showed a delay in transition and apex differentiation compared to ‘QR’. We suggest a higher sensitivity of ‘SS’ to temperature. We think temperatures during the ontogenesis for the second sowing date (12 °C) is a threshold temperature for apex transition of ‘SS’. | |
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