BACKGROUND. The grassmeter non-destructive
method was used to estimate dry matter yield (DMY)
of 24 annual self-reseeding legumes. The possibility
was evaluated of using the grassmeter as an alternative
to conventional destructive quadrats for large
field plot experiments.
METHODS. The linear regressions between sward
height measured by the grassmeter and DMY were
analysed. Three types of regression equations were
calculated: (i) ‘general’, a single equation including
the three-year set of height/DMY pairs of data; (ii)
‘specific’, one regression equation for each species;
(iii) ‘preliminary’, calculated from the data collected
in the spring and autumn cuts of the first year.
RESULTS. The ‘general’ calibration gave a satisfactory
estimate of DMY (R2=0.55). The ‘specific’ calibration
was particularly accurate for Trifolium
brachycalicynum “Osilo” (R2=0.88), T. squarrosum
“Chilivani” (R2=0.81) and Medicago polymorpha
“Circle Valley” (R2=0.81), but not for M. rugosa
“Sapo” (R2=0.22) and “Paraponto” (R2=0.26). The
‘preliminary’ calibration, which was based only on the
destructive assessment of DMY at the first cut, provided
reliable estimates of DMY until the sward conditions,
namely cover rate and weeds, were comparable
to those of the calibration period. The coefficient
of variation of the DMY estimate based on the
grassmeter ‘general’ calibration was about 10% lower
than that of the DMY measured with conventional
quadrats.
CONCLUSIONS. Results suggest that the grassmeter
could effectively replace destructive measurements
for estimating the DMY of annual self-reseeding
legumes, thus reducing labour requirements and
number of samples to be processed, or increasing,
when needed, the number of accessions to compare
and hence the inference of the experiment
