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HEAD EMERGENCE IN FORAGE GRASSES IN RELATION TO FEBRUARY–MAY TEMPERATURES AND THE PREDICTING OF EARLY OR LATE SPRINGS
Author(s) -
Beddows A. R.
Publication year - 1968
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.1968.tb00557.x
Subject(s) - perennial plant , inflorescence , forage , lolium perenne , biology , agronomy , phenology , air temperature , altitude (triangle) , environmental science , botany , geography , mathematics , meteorology , geometry
The date of the spring appearance of inflorescences in herbage plants has been studied at the Welsh Plant Breeding Station, Aberystwyth (Lat. 52”N.), and data collected between 1926–64 examined for Lolium, Dactytis and Phleum . The seasonal variation in mean date of emergence showed a range in perennial ryegrass of 14 to 29 days, in Italian ryegrass 14 to 20. in cocksfoot 18 to 25, and in timothy 14 to 19 days. Inflorescence initiation under field conditions is a response to increasing photoperiod, but the rate of development and the date of appearance is controlled by the weather, especially temperature. There is a negative correlation between accumulated temperature and head emergence. The mean emergence date provides a good index of the year by year heading sequence of the different cuuivars. A study of the air and soil temperatures between February and May showed that the accumulated temperature above 42°F for March, and the number of times that the soil temperature at 4 in. deep reached and exceeded 42 T provide a means for predicting the degree of earliness or lateness of spring in relation to head emergence in grasses. Observations on the phenology of flowering plants and especially fruit trees can also be used for prediction. This second method is simpler and more direct and it has the further advantage of providing a slightly earlier forecast.