Assessing emergence of bean (Phaseolus vulgaris L.) seed lots in France: Field observations and simulations
Résumé
Field emergence is crucial in determining the yield and quality of French beans for the canning industry. The aim of this study was to analyze the variation in bean emergence results, particularly to determine the relative influence of seed characteristics and sowing conditions. During 2004 and 2005, at two sites in France (North: 50. 1 degrees N, 3 degrees E; West: 47.3 degrees N, 0.3 degrees W), field experiments were carried out in order to obtain information on bean emergence under a range of sowing conditions. Four seed lots of the cultivar Booster with differing germination and seedling growth parameters determined under laboratory conditions were sown. These field results were also used to compare observed results in the field with the simulations of a crop emergence model. Subsequently, the effects on crop emergence of a greater diversity of seed lots in the three main French cropping areas were simulated using the model. In the field experiment, germination rates were always high (80-100%). In contrast, final emergence rates varied from 56 to 90%, emergence lasting from 9 to 28 days. These differences were large between sowing situations but small between seed lots. Emergence was mainly delayed by low temperatures (<10-15 degrees C or dry conditions, and emergence rates were reduced to 56% by soil crust formation. When compared to field observations, the model accurately predicted germination while emergence predictions could be improved by including a correction factor that decreased the elongation rate. The simulation study confirmed the results of field observations over a wider range of climatic conditions and with a greater diversity of seed lots. Germination always lasted less than 7 days and was 100% in most cases. Emergence rates reached at least 85% for 75-100% of the years. Differences between seed lot results were mainly due to differences in emergence length of time (6-19 days). The simulations showed that it may be possible to sow earlier than usual in two areas (10-20 days), especially for seed lots with lower temperature requirements. Modelling complemented the field experiments and allowed the risks of different sowing conditions to be statistically estimated. Seed lots industrially processed by seed growers and seed companies should be analyzed using the input variables of the emergence model to determine the variability of their characteristics and their possible influence on emergence