New Poinsettia Genetics and Controlled Substrate Moisture Growing.

Summary: This project builds upon the prior AHDB funded programmes (2015/16 and 2017/18) on developing new approaches to produce Poinsettia, including an assessment of new varieties and the potential of using deficit irrigation to control stem height without reliance on PGRs. In prior years, the trials have successfully supported growers in driving forward quality and maintaining the UK quality USP for this important product. As such, the trials are now one of the highlights of the poinsettia growers’ calender. We propose to continue the variety assessment and improvement programme. The trials are the only independent variety trials conducted within the UK and are a critical part of grower choice for this crop. We will test 12 accessions across each of three grower sites in the UK. In addition, we will build on encouraging results from the 2017/18 work which showed that “dry growing” techniques could control Poinsettia growth without the need for any PGRs. The approach used sensors to monitor substrate moisture remotely and demonstrated key control parameters (e.g. wilting points, phases of sensitivity to water stress etc). In 2018/19 we propose to extend the approach by applying a targeted and automated Regulated Deficit Irrigation (RDI) treatment to limit stem height, and we will compare this to a human deployed “dry growing” approach. We will provide novel insights into how to optimise RDI and critical underpinning knowledge that will de-risk an exciting and new growing technique.

Aims and Objectives: The UK poinsettia industry has had a high reliance on relatively few poinsettia varieties. The variety with the largest penetration is Infinity (c. 65% of the UK 2016/17) followed by others such as Christmas Feeling, Prima, and Christmas Eve. However, there is considerable interest in the use of new varieties for the UK market. There are concerns that some varieties, which have been in the market for a number of years, are now starting to show non-typical or variable traits and habits. As a consequence, AHDB research in 2015/16 and 2017/18 evaluated the performance of 12 existing and new varieties for the UK market. These varieties were also tested on three different nurseries to show the resilience of the product to different growers.  Our aims in this project are to extend the AHDB Poinsettia assessment programme and test a further series of varieties for 2018/19. In addition, we will provide an effective KE forum for growers to discuss varieties and growing techniques

Furthermore, given significant pressure on growers to reduce the use of PGRs and ongoing concerns over exiting chemical regulation, in 2017/18 we examined the potential of dry growing by imposing moisture deficits to regulate plant growth. In particular, we examined the percentage moisture content at which plants wilted, and also the performance of Delta-T moisture probes, datalogging and telemetry. This trial confirmed the potential of using moisture deficits for the growth control of Poinsettia, and also NIAB EMR’s earlier work on the pot dryness safety limits for the process (i.e. the % moisture below which the plant wilts and quality is lowered). The trial also showed that the Delta T technologies were robust and accurate in a commercial setting.  Our aims in the proposed project are to provide further underpinning knowledge that will increase grower confidence in the  technique, but also test highly novel automatic irrigation control systems capable of applying and managing RDI at the critical stage of plant development.