| Abstract: | The winter growth of winter white lupin (cv. Lunoble) was investigated.Over three consecutive years, 1987–1989, it was sown atdifferent times at Lusignan (France) and in 1989, at nine differentlocations with various sowing times. The production of primordia,the vernalization requirements and the final number of leaveson the main stem were related to field measurements of dailymaximum and minimum temperatures. A statistical model for the main apex growth with a system oftwo equations was developed, with a threshold level for leafprimordia production at 3°C. The number of leaf primordiaproduced by a vegetative apex (y) in terms of the cumulativesums of temperature over 3°C (x) followed the curvilinearregression y = 4.76+ 0.0268x + 0000015 6x2. The upper and lowertemperature limits for vernalization were estimated as 14 and1°C respectively. The vernalization requirements of a vegetative apex (y) decreasedwhen the number of initials produced (x) increased accordingto the negative exponential regression y = exp (7.2— 0.02626.x). The two equations were used for the prediction of the finalnumber of leaves of a lupin crop. The predictive accuracy ofthe model was checked against independent data. The agreementbetween observed and predicted final leaf number was often close,but some deviations did occur with low leaf number. The modeldescribed most of the growth phenomena which occur during thephase sowing to floral initiation of the main stem of a winterlupin crop, and its possible uses are discussed Lupinus albus L, white lupin, growth, model, vernalization, primordia, apex, thermal time |
