Artificial Drying Characteristics of Hybrids and Local Strains

Several hybrids were tested throughout five years to find the differences of the artificial drying velocities. In Figure 6 the most typical average drying velocity lines can be seen from the first year experiments (1993). The differences in velocity run up to 45% between the fastest and the slowest hybrid.

Figure 6. Average drying velocities of four selected hybrids from the 1993-experiments as a function of initial moisture content.

In 1993 the artificial drying characteristics of hybrids followed the tendencies that higher drying velocity possessed bigger slope (Figure 7). This means that hanging the initial moisture content does not change the differences in moisture loss. For example, Fanion always dries the slowest and Occitan the fastest among these varieties.

Figure 7. The ranking list of 1993 experiments. Hybrids on the upper right corner are considered good (fast drying) ones, meanwhile hybrids on the left bottom are slow (bad) types.

The result of the 1994 experiments can be seen in Figure 8^2*. The hybrids Sze DK 371 and MTC 344 have nearly the same drying velocities, but the slopes are different. This denotes that in lower initial moisture content (X_i < 0.4) MTC 344 is decreasing slower its velocity than Sze DK 371. The same can be observed for Sze DC 488 and TC 3515.

Figure 8. The slopes of velocity lines as a function of average drying rates of hybrids in 1994-experiments.

2 ^* The graphs of average velocity lines, the equations and R² values of all the drying experiments can be seen in Appendix 2.

Measurements in 1995 (Figure 9) differ from the previous ones. The drying velocity of MTC 344 is still high but its slope is much slower. The correlation between drying velocity (X/) and slope (tg) has changed. In 1995-year study the higher drying velocity was not followed by bigger slope. There were types with the same velocity but different slope (Stira and P 3769), and hybrids with different velocity but the same slope (MTC 344 and Marista).

Figure 9. Results of 1995-year examinations. In this case higher average drying velocity did not followed by bigger slope of velocity line.

The same tendency can be seen in Figure 10 (1996-year studies) and more in Figure 11 (1997-year studies). In Figure 12 (1995, KU Leuven) the correlation between slopes and average velocities is again higher. The reason is evident if we look at the range of the initial moisture contents, where the measurements were done. Table 1 shows the average values of the initial moisture contents of the studied range in each year.

Table 1. The average values of measurement ranges of initial m.c. X_i.

Year 1993 1994 1995 1995

KUL 1996 1997

Average value of initial

m.c., X_i [kg/kg] 0.223 0.265 0.575 0.294 0.416 0.589

Figure 10. Slope of average drying velocity lines of 1996-experiments as a function of average drying velocities.

Figure 11. Ranking list of hybrids measured in 1997.

Figure 12. Results of the experiments carried out in 1995/96 at KU Leuven. Higher slope of velocity lines was found at hybrids having faster average drying velocity.

In 1993, 1994 and 1995 (KU Leuven) experiments the hybrids were harvested with lower initial moisture contents. In 1995, 1996 and 1997 the grain samples were more moist due to the weather conditions in each autumn (Időjárási havijelentés / Monthly Weather Report, 1993 … 1997)^3*. This deviation can be studied in the connection between slopes of average velocity lines and the drying velocity lines.

There were also differences in drying velocities between the two local strains (Pignoletto, Sárga lófogú) examined in 1996 (Figure 10) although they both were ranked as fast drying types with big slopes.

The ranks of hybrids, which were measured more than one year were studied. We have already concluded that MTC 344 showed high average drying velocity in the years 1994 and 1995 (Figures 8 and 9), but it was middle type in 1996 (Figure 10). Florencia was middle in 1993 (Figure 7) and 1997 (Figure 11), but well in 1996 (Figure 10). The average drying velocity of Stira was intermediate in 1995 and 1997, but slow in 1996 (Figures 9, 11 and 10). Helga performed middle drying velocity in 1996 (Figure 10), and fast in 1997 (Figure 11).

However, the fact is have to be taken into consideration that each year different hybrids were presented beside the above reported ones (Florencia, Helga, MTC 344 and Stira), and as mentioned before the initial moisture contents were not the same, too. Thus their positions in the ranking list are relative and can be different in every year.

3 ^* Appendix 3. contains the monthly precipitation values between 1993 and 1997 measured at Mosonmagyaróvár meteorological station.

The results of the different year examinations of hybrids were plotted on the same graphs (Figures 13, 14, 15 and 16). Thus the average drying velocities could be studied with wider range of initial moisture contents than by the yearly evaluations. In this manner polynomial equations can describe more precisely the measured drying velocity points than linear ones.

Figure 13. Average drying velocity as a function of initial moisture content of two-year experiment of Helga.

Figure 14. Polynomial fitting of the measured velocity points of Florencia in 1993, 1996 and 1997 experiments together.

Figure 15. Three-year study of MTC 344 resulted a polynomial curve of average drying rate as a function of initial m.c.

Figure 16. The drying velocity vs. initial moisture content showed nearly linear relationship in the 3-year study of Stira.

Does it mean that the average drying velocities can be described more accurately using polynomial equations instead of lines, which were presented earlier in this chapter? Yes, the polynomial curve fits better to the measured points.

On the other hand polynomial curves are starting to deviate from a line at very low and very high initial moisture contents (0.2 < X_i < 0.6 kg/kg). In practice maize

hybrids are to be harvested between X_i = 0.25 … 0.40 kg/kg moisture contents, where the section of polynomial lines are nearly linear. Hence linear equation can be used for average drying velocity points in this initial moisture content range. However polynomial fitting is needed when the artificial drying velocity is studied in wide range of initial moisture content (Figure 17).

Figure 17. Comprehensive graph of drying velocities of the four examined hybrids showing their drying types.

The charts on Figure 13 … 17 also proved that the results of different years could be compared together instead of the evident meteorological differences. This indicates that the artificial drying characteristics are independent of the environmental conditions.

Hereby these characteristics must be genetically determined.

3.4.3. Preliminary Examinations for Revealing the Inheritance of Artificial