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Poster Session
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Researches of spectral feature and
growing monitoring of rice
- Relationship between paddy spectrum and LAI or TDM
Initial analysis of data shows that the relationship between rice reflectance of single band and LAI or TDM is not very ideal. But by using regression analysis form R and NIR band with 4 spectrum combinations with 6 mathmodels,, we have selected the best spectrum combination (D/C) and the best correlation model F( Y=AXB).
Because the reflectance before and after rice heading are different in data analysis, the rice growing period is divided into 2 parts.
Table 1 shows the power regression coefficient between D/C and LAI or TDM is highest (0.961 and 0.928 respectively).
Using the D/C in 1988 and 1989 as one correlated variables and the
LAI or TDM in 1988 and 1989 as the other correlated variables,
we got the power regression coefficients of individual variety and
total varieties of rice. Table 2 shows, before rice heading, correlation between
D./C and LAI as well as TDM are significant for either individual variety and total varieties.
Table 1 & Table 2
Using the D/C of 4 rice varieties in 1988 or 5 rice varieties in 1989 to make regression analysis with LAI or TDM (before rice heading, 82 samples), the results are:
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In 1988 | YL = 0.301 X0.865 |
( r = 0.900) ......(1) |
| YT = 8.684 X1.100 |
( r = 0.892) ......(2) |
| In 1989 |
YL = 0.345 X0.800 |
( r = 0.961) ......(3) |
| YT= 12.44 X0.992 | ( r = 0.928) ......(4) |
( X=D/C, YL = LAI and YT = TDM )
When using the total of 1988 and 1989 (before rice heading 173 samples) to make the regression analysis with D/C and LAI or TDM, the reaults are:
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Y = 0.354 X0.794 |
(r = 0.933)......(5) |
| Y = 10.982 X1.018 |
(r = 0.903)......(6) |
From the above results of regression analysis, it is found that power correlation between D/C and LAI or TDM before heading is not limited by rice varieties.
After rice heading, the reflectance from paddy canopy is the mixed one from leaves and panicles of rice. Especially after the beginning of milk stage, because of differences in speed of grain filling and changes of the ratio of leaf and panicle, the spectral reflectances of different plots diverse greatly and the correlation between D/C and TDM (single variety or total varieties) is very low. But using following formula to make standardized process, the result is satisfactory .
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..............Eq. 7 |
(X1' is the value after standardized processing, Xi is observed value and K is the number of observations after rice heading) Using 103 samples (after rice heading) to make the regression analysis between D/C and TDM, the correlation reached to extreme significance level (Tab. 2) and the formula as follows;
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Y = 0.924 X0.741 | (r = -0.901)......(8) |
(X is D/C and Y is TDM)
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