Research conducted over several years by Italian research institute LANDLAB in Vicenza studied growth height and biomass production for Lolium perenne, Poa pratensis and Festuca arundinacea. Barenbrug Research in the Netherlands carried out the same research a few years later for Festuca rubra spps. Analyses of cumulative heights and mass of material during one growth season have demonstrated that these factors are positively correlated. This means that from now on a single grass height measurement can be safely assumed to establish that a variety has low biomass production.
Biomass was established in two European locations for a large number of varieties. The figure below gives an overview of the varieties Lp, Pp and Fr, the biomass of which has been determined. Varieties that produce a lot of clippings were indexed at 100; the lower the index (<100), the lower the volume of clippings a variety produces. A variety indexed at 62, for example, produces up to 38% less biomass than a variety indexed at 100.
The figure below provides an overview of the totalled biomass weights for perennial ryegrass as measured during the growth seasons of 2013 and 2014.
Growth height is the second LMT criteria. A predominantly slow-growing variety will generally stay low. The figure below provides an overview of cumulative biomass production for several chewings fescue varieties. Based on an index of 100 for the tallest-growing variety, the lowest-growing variety amounts to 77, a 23% reduction.
The figure below gives an overview of the cumulative growth heights during the growth season. The lower the index, the slower the regrowth and therefore the lower the growth height.
How does a variety obtain the LMT label?
Varieties are eligible for the LMT label if their growth height and biomass are at least 20% lower than the reference grass in the test. For chewings fescue, the reference was Barustic, resulting in a growth height reduction of 23% for Bargreen. Perennial ryegrass has an even better score: a biomass reduction of almost 40%.
Mow Saver is made up of 100% LMT varieties, resulting in a score/advantage of at least 35%.
How was the LMT research carried out?
LMT was conceived at LANDLAB, the independent test centre in Vicenza (Italy), where sowing trials were conducted with the Barenbrug turf grass portfolio, in stripes as well as plots patterns. The research aimed to determine the biomass and growth heights of these varieties, as well as any correlations between biomass and growth heights (in cm). Biomass was measured from the stripes, whereas heights were measured from the plots, according to the following protocol:
Biomass is collected and measured as soon as the grass in the control stripe reaches a height of 35 mm. The biomass produced by each plot is then divided by the number of days between two consecutive mowing sessions. This provides us with weekly biomass production.
The difference in plant height between two consecutive mowing sessions is measured and then divided by the number of days between two consecutive mowing sessions -> this enables us to calculate weekly growth.
The pictures below give an impression of the mowing activities for biomass determination.
Research setup for biomass determination.
When plotting the height data against biomass data, a clear correlation can be observed. This correlation applies to varieties that produce little biomass as well as those that produce a lot of biomass (such as Barrage). We may conclude that a single height measurement suffices to determine the growth characteristics of a variety and whether the variety is worthy of the LMT label.
Falling disc plate for height determination.