Phase change in citrus: The effects of main stem node number, branch habit and paclobutrazol application on flowering in citrus seedlings

SummaryTwo studies were carried out to identify the effects of several factors including plant size (defined as the number of main stem nodes), growth habit and paclobutrazol application on the length of the juvenile period of citrus seedlings. In the first group of experiments, seedlings were grown from seed of ‘West Indian’ lime (Citrus aurantifolia (Christm.) Swingle), ‘Marsh’ grapefruit (Citrus paradisi Macf.) and ‘Meiwa’ kumquat (Fortunella × crassifolia Swingle (pro sp.)). Seedlings were initially grown under rapid-growth controlled environment conditions of 30/25°C day/night temperatures, 16 h days of 650 µmol s-1 m-2 and high relative humidity for 5–8 months and maintained as single stemmed plants until the main stems had more than 100 nodes. They were then treated with one of four rates of paclobutrazol as a root-drench and transferred to mild environmental conditions in a greenhouse (25°C maximum/15°C minimum) to assess subsequent branch development and flowering response. ‘West Indian’ lime and...

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