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The physiology and manipulation of terminal and lateral bulb units in narcissus - HH3704SBU

Little is known of the factors controlling the initiation of bulb units and flowers in narcissus, yet it is highly likely that much variability within a crop is associated with lateral bulb units being initiated several months after terminal units. The lateral units are smaller, less likely to initiate flowers and rarely produce further lateral bulb units, so the presence of both types of unit in the bulb is an important contributor to the variability within and between crops.

The objective of this project is to investigate the effects of cultural and environmental conditions on the growth and development of terminal and lateral bulb units and subsequent flower initiation and development. It will enable protocols for manipulating the relative growth and development of both types of unit to be determined. These will improve the uniformity and predictability of bulb crops and offer the possibility of 'designing' bulbs for specific end-uses. Uniform bulbs are better for precision planting and for sales in ‘pre-packs’. Minimising growth of potentially non-flowering lateral bulb units would help flower production or bulb forcing, where a high ratio of flower numbers to bulb weight is preferred. Increasing the numbers of lateral bulb units and reducing the number of flowers would increase the speed of multiplication of bulb stocks.

This project will provide strategic research necessary for the development of innovative approaches for improving the efficiency of narcissus production. It will improve the accuracy of scheduling the crop to meet market requirements and will underpin the development of DEFRA’s policy for a sustainable bulb industry. Further, as an ornamental crop grown on a large scale and marketed widely, narcissus is very relevant to ‘quality of life’ issues.
1. To determine the influence of temperature and water supply (rainfall and/or irrigation) on:
- The date of terminal and lateral bulb unit initiation
- The date of floral initiation in terminal and lateral bulb units
- The yield and form of bulbs from these treatments
We expect this to provide physiological information that will underpin the development of techniques enabling the manipulation of crop characteristics according to specific requirements.

2. To quantify the effects of supra-optimal hot-water treatment on:
- Bulb unit initiation
- Flower viability
This investigation may enable an alternative means of controlling bulb unit initiation to be exploited.

3. To develop and validate techniques for manipulating the relative growth and development of terminal and lateral bulb units by:
- Growing crops in controlled conditions simulating those needed for producing differential growth effects on terminal and lateral bulb units
- Growing crops in the field at three climatically contrasting sites
This will inform the development of agronomic practices for use by growers to manipulate narcissus crops.
Project Documents
• Final Report : HH3704SBU SID 5 Final Report   (1070k)
Time-Scale and Cost
From: 2001

To: 2005

Cost: £281,792
Contractor / Funded Organisations
Warwick - HRI, Horticulture Research International
Allocated - WHRI              
Sustainable Farming and Food              
Sustainable Production              
Fields of Study