*3.4. Grain Yield and Grain Yield Components*

Comparing between years, grain yields were significantly lower in 2014 (3.9 t ha<sup>−</sup>1) than in 2015 (4.5 t ha<sup>−</sup>1). There was also a significant interaction between year and SA in the experiment (ANOVA results not shown). As shown in Figure 3, the highest value was observed in SA15 in 2014 (albeit not significantly different from the SA25, SA35 and SA45 during 2014, and SA45 in 2015), while in 2015, the highest value was obtained in SA15 (although not significantly different from SA25 and SA35 in 2015).

**Figure 3.** Comparison of yields across treatments and years (2014 and 2015). Columns with common letter are not significantly different at *p* < 0.05.

Among treatment factors, ANOVA results indicated that V significantly affected grain yield in each year (data not shown), while SA and SD did not. Higher (although not statistically different) yields were observed in V2 and V3, while lower grain yields were observed in V1 in both years (Table 4). A significant SA × V interaction on grain yield was also observed in both years. Comparing SA at each level of V during 2015, a lower grain yield of SA45 (albeit not significantly different from SA25) was observed in the V3 level, while in the V1 and V2 levels, grain yields in all SA treatments were similar (Table 5). In 2014, however, there were mixed yield trends when comparing SA at each level of V: Significantly lower yields for younger seedlings (SA15) in V1 and V2, while lower yields in late transplanted seedlings (SA45) in V3. In 2015, comparing V at each level of SA showed significantly lower yields in V1 compared with the other two varieties (particularly under SA15, SA25, and SA35), while grain yields in V2 and V3 were the same under seedling age levels. Similarly, in 2014, grain yields were lower in V1, although not significantly different from V3 under SA25 and SA45.

In terms of grain yield components, no significant effect of year (2014 vs. 2015) was found in any of the yield components. However, in terms of experiment treatment effects in each year, the number of panicles (per m2) was significantly influenced by all three factors (SA, SD, and V) during 2014 and by two factors (SD and V) in 2015. However, no significant interaction effects of treatments were found in both years. As shown in Table 4, across seedling age the significantly highest number of panicles was observed in SA25 particularly in 2014, and the lowest in SA45 (although not significantly different from SA15 and SA35 in 2014 and from SA15, SA25, and SA35 in 2015). Across seedling densities, a greater number of panicles per m2 were observed with higher seedling densities than with lower seedling densities. In both years, the highest number of panicles was observed in SD5 (although not significantly different from SD3 in 2015); it was significantly lowest in SD1. Across varieties, V1 consistently produced the significantly highest number of panicles compared with the other varieties; no significant difference in the number of panicles was found between V2 and V3 varieties in both years.



1 In a column and within the factor, significantly *p* significance, (\*\*) and single(\*) asterisks mean that the F-value are significant at 1% and 5% level, respectively, and ns means not significant.

 1.


**Table 5.** Effects of seedling age × variety (SA × V) interaction on grain yield (2014 and 2015) and percent filled spikelet (2014) and of seedling age × seedling density (SA × SD) interaction on 1000–grain weight (2015) 1.

<sup>1</sup> In a column and within the same year, means with the same lowercase letter are not significantly different (comparison of SA at each level of V for grain yield and percent filled spikelet, and comparison of SA at each level of SD for 1000-grain weight). In a row and within the same year, means with the same uppercase letter are not significantly different (comparison of V at each level of SA for grain yield and filled spikelet, and comparison of SD at each level of SA for 1000-grain weight).

Significant effects of SA, SD, and V were observed on the number of spikelets per panicle (spikelet count) in 2014, while in 2015 only significant effects of SA and SD on spikelet count were noted. No significant interactions were found among factors on the spikelet count in both years. Across SA treatments in 2014, the spikelet count was highest in SA45, followed by SA25, then SA35 and SA15, although there was no significant difference between SA15 and SA35 and between SA25 and SA35 (Table 4). In 2015, there was an opposite trend: SA45 provided the lowest spikelet count among the four SA treatments. Highest spikelet count was recorded in SA25, followed by SA15 and SA35, but as in 2014, the difference between SA15 and SA35 was not significant. Across SD, highest spikelet count was observed in SD1 and the lowest was seen in SD5 in both years. The difference in spikelet count between SD3 and SD5 was only significant in 2014. Across varieties, the highest spikelet count was found in V3 and the lowest in V1 in 2014. Spikelet counts were similar in all varieties used in the 2015 experiment.

In 2014, the 1000-grain weight (1000 GW) was significantly influenced by V, while by all three factors (SA, SD, and V) in 2015. There was a significant SA × SD interaction on 1000 GW in 2015. In both years, consistently highest 1000 GW was produced in V2, with the lowest seen in V1 (Table 4). In 2015, comparison of SA at each SD level (Table 5) indicated that SA15 was significantly highest among the four SA treatments under SD1 and SD3, whereas similar values were observed among SA25, SA35, and SA45. Under SD5, no difference in 1000 GW was found among the SA treatments. Comparing SD at each level of SA, a significant difference in 1000 GW was only found under SA15 level, where SD5 < SD3 < SD1; the differences in means across SD were not significant at the SA25, SA35, and SA45 levels.

The percentage of filled spikelet was significantly influenced by SA and V in 2014 and in 2015 by V. There was also a significant SA × V interaction on percent filled spikelet during 2014. Comparing SA at each level of V (Table 5), the lowest percent filled spikelet was observed in SA15 under V1 and V2 levels, although SA15 was not significantly different from SA25 and SA45, especially under V2. However, under V3, SA15, SA25, and SA35 were similar but were significantly higher than SA45. Comparing V at each level of SA (Table 5), significant differences in percent filled spikelet between varieties were observed in SA15, SA25, and SA45. Percent filled spikelet of V3 was significantly higher than that of V1 and V2 under SA15, and significantly higher than V2 under SA25. However, V3 was statistically similar to V2 under SA45, but significantly lower than V1. Between V1 and V2, values were similar under SA15, but V1 was significantly higher than V2 under SA25 and SA45. Mean harvest index (HI), was relatively higher in 2014 (38.7%) than in 2015 (32%), since both grain yield and dry biomass were

higher in 2015 (data not shown). All treatments and their interactions did not influence HI in 2014, but, in 2015, HI was significantly influenced by seedling density. SDI had higher HI compared with other SD treatments (Table 4), whereas SD1, SD3, and SD5 were not significantly different.
