Winter growth of anutumn-sown white lupin (Lupinus albus L.): main apex growth model
1991
Huyghe, C.
The winter growth of winter white lupin (cv. Lunoble) was investigated. Over three consecutive years, 1987-1989, it was sown at different times at Lusignan (France) and in 1989, at nine different locations with various sowing times. The production of primordia the vernalization requirements and the final number of leaves on the main stem were related to field measurements of daily maximum and minimum temperatures. A statistical model for the main apex growth with a system of two equations was developed, with a threshold level for leaf primordia production at 3 degrees C. The number of leaf primordia produced by a vegetative apex (y,) in terms of the cumulative sums of temperature over 3 degrees C (x) followed the curvilinear regression y = 4.76 + 0.0269x + 0.0000156x2. The upper and lower temperature limits for vernalization were estimated as 14 and 1 degrees C respectively. The vernalization requirements of a vegetative apex (y) decreased when the number of initials produced (x) increased according to the negative exponential regression y = exp (7.2 - 0.02626x). The two equations were used for the prediction of the final number of leaves of a lupin crop. The predictive accuracy of the model was checked against the independent data. The agreement between observed and predicted final leaf number was often close, but some deviations did occur with low leaf number. The model described most of the growth phenomena which occur during the phase sowing to floral initiation of the main stem of a winter lupin crop, and its possible uses are discussed.
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