The use of the grassmeter as a simplified method to estimate dry matter yield on annual self-reseeding medics and clovers [Sardinia; Medicago; Trifolium]
2003
Franca, A. (Consiglio Nazionale delle Ricerche, Sassari (Italy). Istituto per il Sistema Produzione Animale in Ambiente Mediterraneo (ISPAAM)) | Porqueddu, C. (Consiglio Nazionale delle Ricerche, Sassari (Italy). Istituto per il Sistema Produzione Animale in Ambiente Mediterraneo (ISPAAM)) | Roggero, P.P. (Università Politecnica delle Marche, Ancona (Italy). Dipartimento di Scienze Ambientali e delle Produzioni Vegetali) | Caredda, S. (Sassari Univ. (Italy). Dipartimento di Scienze Agronomiche e Genetica Vegetale Agraria)
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. 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 data collected in Spring and Autumn cuts of the first year. The "general" calibration gave a satisfactory estimate of DMY R**2 = 0.55. The "specific" calibration was particularly accurate for Trifolium brachycalicynum Osilo R**2 = 0.88, T. squarrosum Chilivani R**2 = 0.81 and Medicago polymorpha Circle Valley R**2 = 0.81, but not for M. rugosa Sapo R**2 = 0.22 and Paraponto R**2 = 0.26. The "preliminary" calibration, 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 the ones of the calibration period. The coefficient of variation of DMY estimate based on the grassmeter "general" calibration was about 10% lower than the one of DMY measured with conventional quadrats. 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
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