*3.3. Crop Growth and Development*

On average, total crop growth duration (sowing to harvest) was longer in 2015 than in 2014 by about 4 d (Table 2). SA and V significantly affected crop growth duration among the treatments. No significant interactions between treatments were revealed in the ANOVA. The number of days from sowing to panicle initiation and from sowing to harvest was highest in SA45 and lowest in SA15 between SA treatments. Mean differences in total crop growth duration between SA45 and SA15 were 17 d in 2014 and 20 d in 2015. The mean difference between SA35 and SA15 (10–13 d) was observed in both years, while a difference of 6–7 d was observed in both years between SA25 and SA15. In terms of plant growth duration in the main field (from transplanting to harvest), the older the seedlings at transplanting, the shorter the crop duration. This means that SA45 had the shortest duration and SA15 had the longest duration in the main field in both years. A difference of 4–5 d was observed between SA15 and SA25, 7–10 d between SA15 and SA35, and 10–13 d between SA15 and SA45. In terms of varieties, V3 had the longest crop growth duration, followed by V2 and V1, respectively.


**Table 2.** Crop duration from sowing to panicle initiation and harvest, 2014 and 2015 wet seasons.

<sup>1</sup> Within each column, season and treatment, means followed by the same letter are not significantly different at *p* < 0.05. In the ANOVA results, single (\*) asterisk means that the F-value was significant at 5% level, while ns means not-significant.

In general, the average number of tillers (per hill) was higher in 2015 than in 2014 (Table 3). The tillering ability of the rice plants was significantly influenced by seedling age, seedling density, and variety. There was, however, no significant interactions among treatments on tiller count (number of tillers per hill) in both years. In 2014, across seedling age treatments, average tiller count at around panicle initiation stage (42–44 DAT) was highest in SA15 (11.7) and lowest in SA45 (6.6), while SA25 and

SA35 had the same number of tillers (10.6; Table 3). In 2015, a similar trend was observed: Highest average tiller count was seen in SA15 (15), and the lowest was observed in SA45 (9.8). SA25 and SA35 had similar tiller counts (12.7). During 2014 and at the panicle initiation stage, SD1 provided the lowest tiller count across SD treatments, while SD5 had the highest count, although not significantly it was different from SD3. In 2015, differences in tiller count among seedling age treatments were significant, with average tiller counts being highest in SD5 (14.8), followed by SD3 (12.9). The lowest was noted in SD1 (10.5). Across varieties, as expected, V1 provided the significantly highest average tiller count in both years (10.9 in 2014 and 14.5 in 2015). In 2014, tiller counts of V2 and V3 were similar, while in 2015, V2 had higher tiller count than V3.


**Table 3.** Mean comparison of plant height and tiller count at the panicle initiation stage, 2014 and 2015 wet seasons 1.

<sup>1</sup> Within each column and treatment, means followed by the same letter are not significantly different at *p* < 0.05. In the interaction significance, ns means that the F-value is not significant.

On the average, plants were taller in 2015 than in 2014 (Table 3). At the panicle initiation stage, only seedling age and variety significantly influenced plant height. No significant interactions among treatments on plant height were observed. In both years, early transplanted seedlings (SA15 and SA25) were significantly taller than late transplanted ones (SA35 and SA45). In 2014, the mean difference in height between SA15 and SA45 was about 15 cm, while in 2015, the difference was about 9 cm. No significant difference in plant height was found between SA15 and SA25 in both years; but between SA35 and SA45, a difference of about 9 cm was observed in 2014. Across varieties, plant heights of V2 and V3 were similar in both years and were, on average, significantly taller than V1 by 10 cm.
