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New Poinsettia genetics and controlled soil moisture growing

Research

PO 021a - New Poinsettia genetics and controlled soil moisture growing

Start Date: 
01/06/2017
Completion Date: 
01/03/2018
Project Leader: 
Simon Pearson, University of Lincoln
Code: 
PO 021a
Industry representative: Graeme Edwards, Woodlark Nurseries
 
AHDB Horticulture Cost: £41,500 
 
Summary: The UK poinsettia industry has had a high reliance on relatively few poinsettia varieties. The variety with the largest penetration is Infinity (c. 80% of the UK volume), followed by others such as Christmas Feeling, Prima, and Christmas Eve. The UK market tends to require slightly taller plants than the typical EU product, with clean red bract colours contrasting against dark green leaves. Prominent cyathia are frequently required, but without pollen.
 
There is now considerable interest in the use and exploitation of new varieties for the UK market. There are concerns that key varieties, which have been in the market for a number of years, are now starting to show non-typical or variable traits and habits. This may be due to issues with stock plant maintenance over a number of years. As a consequence, AHDB research in 2015/16 evaluated the performance of 11 existing and new varieties for the UK market. These varieties were also tested on 3 different nurseries to show the resilience of the product to different growers.
 
These trials in 2015/16 showed dramatic differences between varieties and growers. Some varieties performed badly on all sites (e.g. Pallas which has now been withdrawn from the market) others were inconsistent between site whilst Hera Red, Infinity 2.0 and Astro Red performed well across all sites. This suggests that the latter varieties may be more resilient to different growers than others. There were also significant overall differences between growers, and these differences were not explained. We noted significant differences to approaches to PGR application, some growers used multiple low dose rates of cycocel compared to others who used high dose few applications. There were also differences in glass quality, temperature control and approach to watering and nutrition. We also noted that the plants produced on the most southerly site were dramatically more advanced than the northern sites, despite identical plants and planting dates.
 
In addition the industry is faced by a new emerging threat of the potential loss of cycocel, the key plant growth regulator used by the industry. Given this emerging threat it was considered important to examine new routes, in particular controlled soil moisture growing, to control plant growth. 
 
Feedback from the 2015/16 trials was positive, and it is likely to have had a positive impact for industry variety selection for 2016/17. Following consultation with the industry, we propose here to expand the approach for season 2016/17. In particular, we propose to;
1) Repeat and expand the variety testing program to include 20 varieties, some new but other which are the same as 2015/16. We will also include a number of new non named varieties. With a limited number of varieties (4) we will also examine the effect of two sticking dates (week 30 and 32). This reflects the difference in timing between the sites seen in 2015/16, the plants on the south coast were at least two weeks earlier in maturity than those in the north. This approach enables us to examine variety resilience between year, but also to short cut the selection time for new varieties to enter the market.
2) We will test the new Delta T multiple pot moisture sensors and through this season examine their efficacy with crops of Poinsettia. The sensors will be used to monitor soil moisture in real time on crops of Poinsettia. We will establish there efficacy over time and validate the sensors . To enable future studies on moisture control of poinsettia (dry growing approaches) we will use the sensors to establish the wilting point of poinsettia, and verify that this occurs at the same or similar soil moisture level with different growth stages. We will also examine whether soil moisture deficit growing through September on a small trial batch can be used to control crop growth (as previously indicated in DEFRA funded work by Dr Mark Else at EMR). This work package will provide critical information to underpin future approaches of the use of dry growing for growth control. It will establish the accuracy and reliability of the sensors and the critical points at which the crop wilts. 
 
Aims and Objective: Poinsettias are a major heated crop grown to harvest from November through to the second week of December for the Christmas market. The AHDB Poinsettia trials of 2015/16 evaluated the performance of a 12 new varieties coming onto the market, some (e.g. Hera Red, No. 57) were shown to have excellent production characteristics combined with long post harvest keeping quality. The 2015/16 trials have already had an impact on variety choice for next year, and led to the removal of Pallas from the market and the introduction of No 57, now named Lenora.
 
The varieties were tried on 3 different grower holdings (Pinetops, Delamores and KRN Louth) across the UK. The differences between sites were striking. The crop at Pinteops on the south coast was very advanced, there were clear differences in bract maturity and plant size. It was clear that specific varieties performed consistently across all growers, but others suited (or not) specific growers’ techniques. The reasons for these differences are not known, but the key factors are likely to be environmental differences between sites (light, temperature and glass quality) as well as differences in approach to plant growth regulator treatments. Given the interest in the 2015/16 trials, discussion in the industry indicates that there is now a need to extend the approach. 
 
Therefore, in the 2017/18 we plan to build on the prior work to;
Test a wider range of plant material on the same three sites as 2015/16 but including up to 20 varieties, including pre released numbered material from the key plant breeders. Some of the 20 varieties will be repeats of those used on 2015/16 to establish year to year variety resilience. The use of new material enables the industry to short cut the prolonged variety selection process.
 
In addition, there are now significant concerns that the industry will lose key growth regulators such as cycocel as early as 2017/18. Currently growth regulators such as cycocel as applied to a crop between 5 to 12 times through through its life (depending on grower, variety, dose rates etc). PGR’s have been a critical element of how growers control their crop and deliver product of the correct final specification to key customers. The likely loss of these active ingredients poses a serious threat / issue for the industry. To address this serious threat we have worked to develop two seperate work packages;
1) To assess a range of new active ingredients on Poinsettia growth and quality. This work package is ongoing and will be funded via the existing Pot and Bedding Plant Centre project. This is the subject of a separate but complimentary and co-ordinated proposal led by ADAS.
2) To urgently reassess the potential of using soil moisture sensing, combined with soil moisture deficit growing to control crop growth. This approach is well known and was developed by Dr Mark Else at EMR via a DEFRA project on Poinsettia conducted from 2007 to 2010. In the approach EMR tested some novel soil moisture sensors in conjunction with controlled soil moisture deficit growing. The controlled was grown dry (but controlled with sensors) during key crop development stages, mainly through the period of peak extension rate in September. The approach worked well under experimental conditions and had the potential added benefit of increasing final plant shelf life performance. The work was not taken up as cycocel remained on the available chemical list and there were concerns about the spatial robustness of the sensor. This reflected the fact that the sensor at that time just had a single probe (ie. could only measure a single pot in an entire crop). However, technology developments at EMR and by Delta T the instrument manufacturer have now increased the robustness of the device and one instrument now averages the input from 12 different probes. Given the likely loss of cycocel and this prior work it was thought sensible to reexamine the potential of soil moisture deficit growing and the new Delta T probes in this proposal.
 
 
Benefits to Industry: Poinsettia are one of the most important pot plant crops between July and early December. Up to 8m Poinsettia are sold within the UK market, with c. 3.5 to 4m grown in the UK, and a market value of c. £10m to £12m p.a. at farm gate values (in pot sizes 10 to 17cm). Given that 50% of the UK crop is imported, typically from Holland, these figures suggest a significant potential for import substitution. Given the risks and opportunities for this sector, it is critically important that the industry have clear insight to develop compelling competitive advantages for UK produced crop.

The benefits of these experiments are multi-faceted. It will provide UK growers with effective insight into the commercial performance of a wide range of new Poinsettia varieties benchmarked against current commercial controls. Variety choice is one of the most important decisions made in Poinsettia production, it is a critical factor in determining the commercial success of the crop. The experiments will be robust and be conducted under real commercial conditions.  The experiments will also demonstrate whether varieties are robust and stable under a range of different commercial conditions. We will also examine a new approach (dry growing combined with novel sensors) which attempts to produce Poinsettia without PGRs. This work will be of significant interest as both PGR availability will reduce and there is significant pressure to reduce the use of agrochemicals on all crops. We will also examine the potential of new soil moisture sensors that will underpin future studies on the impact of dry growing for growth control.