Resumo

QUIROGA GARZA, Héctor Mario. Rate of dry matter accumulation of alfalfa in response to climatic variables. Rev. Mex. Cienc. Agríc [online]. 2013, vol.4, n.4, pp.503-516. ISSN 2007-0934.

The information needed for the development of growth models of alfalfa based on the effects of climatic factors on its cultivation has been obtained at higher latitudes and with alfalfa of a higher winter dormancy grade than the alfalfa cultivated in Mexico; it is therefore necessary to estimate the response of alfalfa to different climatic variables under the conditions of the Mexican region (25° N). We used information from six assessments of alfalfa varieties under irrigation during the period 2006-2010. The climatological information was obtained from an automated station Adcon Telemetry 840^®. We used the averages for growth, maximum and minimum temperature, daylength, evapotranspiration and accumulation of degree-days (base 5 °C). The response was different in each season: in the winter-spring period all responses were quadratic, with a significant explanation of the variability in the growth rate (GR) of alfalfa (t FS ha^-1 day^-1): 59, 58, 57, 55 and 27%. In the summer-winter period, with the exception of GDD₀₅, all responses were linear and explained 32, 31, 26, 25 and 10% of the variability in GR with respect to HrL, ETo, Tmin, Tmax and GDD₀₅, respectively . The highest minimum temperatures occurred in the summer and, in combination with the highest photoperiod, affected the GR, reducing the time between cuts, FS production, etc. The information generated can serve as a basis for the development of models to estimate the growth of alfalfa under the conditions and latitude of the "Laguna Region".

Palavras-chave : Medicago sativa L.; degree-days; evapotranspiration; photoperiod; temperature.

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