1033 
represent it in order to use the radiosity approach: 
liDav 70(11 March) 
The period is approximately that of the floral initiation. The cover is still small. We can roughly define 4 kinds of 
chnr*s on our study area. There are 5 leaves on each of the 63 main shoots. However, among these 63 shoots, 5 do 
not have tillers at all, 23 have tillers recently bam (2 small leaves) at the node of the first leave (Tl), 12 have 
older tillers Tl (2 bigger leaves), and 23 have tillers Tl (2 big leaves) and T2 (1 leaf). Figure 3 is an example of a 
typical “5 leaves + 2 tillers” shoot, from which representative values of the height of the nodes were taken Table 
1 shows the values required for the description of the canopy. The leaves are numbered following their 
appearance order on the main shoot, so die leave number one is the oldest one. The height corresponds to the 
position of the node of each leaf. The orientations of the leaves are given by azimut and zenith angles. As said 
before, the zenith angles for each leaf are arbitrary chosen by the help of various published images or 
descriptions. The azimuth angle of the first leaf is randomly chosen for each of the 63 main shoot of our study 
area. Then the azimuth angles of the successive leaves are arbitary chosen to follow a rule assuming that a leaf 
approximately appears in the opposite direction than the previous leaf an the same shoot The azimuth directions 
of the first second and more leaves define the direction of the deviation of the x y coordinates of the tillers bom 
on the nodes of the first second and more leaves. The widths and lengths of the various leaves, as well as their 
population, are the outputs of the canopy development part of AFRCWHEAF2. The heights, the deviations of the 
x y position for some elements, and the orientation angles are empirically chosen. 
Tillering at floral initiation stage 
Hgure 3: Example of representation used in order to define node height and leaves orientation. (Soltner, 1978). 
Leaf 
height 
dist. 
directi 
length 
width 
® 
0 
MSI 
1.25 
1.0 
0.0 
77.89 
5.84 
0.0 
100.0 
MS2 
2_5 
2.0 
170.0 
79.67 
5.98 
170.0 
90.0 
MS 3 
35 
0.0 
0.0 
78.62 
5.90 
340.0 
45.0 
MS4 
55 
0.0 
0.0 
48.06 
3.60 
150.0 
45.0 
MSS 
55 
0.0 
0.0 
16.84 
126 
0.0 
0.0 
Tl 1 
25 
2.0 
170.0 
37.30 
2.80 
20.0 
40.0 
Tl 2 
4.0 
35 
170.0 
2252 
1.69 
230.0 
90.0 
T21 
3.0 
2.0 
0.0 
16.84 
1.26 
100.0 
10.0 
Table 1: Characteristic of the structure of a wheat shoot at floral initiation stage with 2 fillets. MS: Main Shoot, 
Tl: filler 1.T2: tiller 2. Height and distance to MS in cm Iength and width in mm Zenith angles ft and 
azimuth angle 9 in degres.