Newanalysis of HGCA data has shown late ripening wheat varieties tend to havelower specific weights but higher yields.
Theresearch, prompted by the quality of last years harvest, looked at data from1994 to 2012 from Recommended Listtrials and the AHDB/HGCACereal Quality Survey. It examined the effect of weather, varietaltraits and region on final specific weight.
Oneof the most interesting findings is that later ripening varieties tend to havelower specific weights but higher yields, according to Dr Ellie Marshall,Research and Knowledge Transfer Manager at HGCA. Crucially, the differencebetween the specific weight achieved in Recommended List trials and commercialcrops is much greater in later ripening varieties.
Inrecent years, there has been a shift to more late ripening varieties on theRecommended List and this has been matched by more being grown on-farm. Themain reason for the shift is that these varieties tend to have higher yieldswhich is one of the main factors growers look for in their crops.
Theresearch shows that the specific weight problems of 2012 are likely to havebeen exacerbated by late maturity but we cant forget that the weather was themost important factor. Growers should consider having a range of maturities inorder to achieve both consistent yields and quality in each season, explainsDr Marshall.
2012was undoubtedly an exceptional year. From 2007 to 2011, the specificweights of Recommended List trial samples closely mirrored those in AHDB/HGCACereal Quality Survey of commercial samples. Average specific weight from 2007to 2011 was around 76kg/hl, which is the standard for nabim groups 1 and 2.
In2012, the average specific weight for Recommended List samples fell just shortof 72kg/hl, while crops in the Cereal Quality Survey were even further behindat 69kg/hl. This is attributed to the far more robust fungicide programme usedfor the Recommended List in comparison to many commercial farms. However,even with robust treatments, specific weight was still considerably lower in2012 indicating that the weather played a key role.
April2012 was wet and gloomy which slowed plant development and reduced grainnumber. These conditions returned during the growth and grain fillingmonths of June and July which saw higher than average rainfall coupled with lowlight levels, particularly in June. These combined to produce lowerspecific weights and a delayed harvest in many parts of the country, accordingto Dr Marshall.
Theresearch also looked at regional differences in the specific weights ofcommercial crops. The most striking finding was that in 2012, the South Westand Midlands had the lowest specific weights of about 68kg/hl, whereas inprevious seasons, specific weights in these regions were among the highest inthe UK.
Averagespecific weights in other parts of the UK were very similar to one another ataround 70kg/hl, this was even the case in Scotland which typically has lowerspecific weights.
Theresearch has not yet shown whether variety choice, weather or other factorswere the main cause of these regional variations.
Forthe longer-term, HGCA has set up a networkof weather stations to help researchers look in greater detail at howweather influences crop development. More information on regional and varietaldifferences will also come out of HGCAsCropping Systems Platform project which will have four UK sites for the2013/2014 growing season.
Alsoavailable is the new Harvest Toolkit whichfeatures harvest results, the mycotoxin risk assessment and many other usefultools and publications.