*3.2. Effects of Sowing Date on LI and* 4*BM*

The LI and 4BM, which were used to evaluate the lodging resistance of rice, were significantly affected by the sowing dates (Figure 3). With the delayed sowing dates, the LI increased significantly in each year (Figure 3A). The LI on SD3 was 22.65% higher than SD1. The LI on SD6 was 19.82% higher than SD4. Additionally, the LI on SD9 was 17.58% higher than SD7. Although the tendency of LI was not always significant in some cultivars, the overall increasing tendencies of LI of the 12 *indica* cultivars were identical (Table 2). In addition, the LI was also significantly affected by locations and years (Table S2). The average LI of the three SDs (SD1, SD2, and SD3) in 2015 at Xindu was significantly lower than that of the three SDs (SD4, SD5, and SD6) in 2017 and the three SDs (SD7, SD8, and SD9) in 2018 at Ezhou by 41.03% and 36.97%, respectively. Contrary to the LI, the 4BM decreased significantly with the delay in the sowing dates in each year (Figure 3B). Compared to the first sowing date, the 4BM of the last sowing date was lower by 35.52%, 57.62% and 47.93% in 2015, 2017 and 2018, respectively. The decreasing trends of 4BM of all the 12 *indica* cultivars were significant (Table 3). Furthermore, the average 4BM of the three SDs in 2015 at Xindu was significantly higher than that of the three SDs in 2017 and 2018 at Ezhou by 255.88% and 179.51%, respectively. However, there was no significant difference in the 4BM between 2017 and 2018 at Ezhou (Table S2). These results indicated that the lodging resistance of 12 *indica* rice cultivars weakened with the delay in the sowing dates in each year and it was greater at Xindu than that at Ezhou. *Agronomy* **2022**, *12*, 2603 9 of 19

**Figure 3.** Comparison of the LI (**A**) and △BM (**B**) for the three sowing dates in each year. LI, lodging index; △BM, the external force that the basal second internode could withstand. All abbreviations imply the same below as well. Vertical bars indicate standard errors (±), *n* = 12 for each SD. Different lowercase letters on the bars indicate significant differences determined by the Tukey test at 5% probability level. **Figure 3.** Comparison of the LI (**A**) and 4BM (**B**) for the three sowing dates in each year. LI, lodging index; 4BM, the external force that the basal second internode could withstand. All abbreviations imply the same below as well. Vertical bars indicate standard errors (±), *n* = 12 for each SD. Different lowercase letters on the bars indicate significant differences determined by the Tukey test at 5% probability level.

Chuan 106B 47.11 b a 69.62 a 78.72 a 107.73 c 143.22 b 164.70 a 117.37 b 139.24 a 147.66 a 345B 63.46 b 88.30 a 89.25 a 123.65 b 138.31 ab 147.49 a 117.79 b 122.94 b 142.64 a Huanghuazhan 70.98 b 69.87 b 84.58 a 136.87 b 165.57 a 181.87 a 116.95 b 137.56 a 150.58 a Jinlongsimiao 78.09 b 86.15 ab 93.18 a 145.71 b 161.86 ab 178.79 a 125.62 b 152.64 a 154.23 a Chuanxiang 29B 80.84 b 99.29 a 94.52 a 163.60 a 169.84 a 178.62 a 155.36 b 165.75 ab 179.44 a Chenghui 3203 83.25 a 92.10 a 91.25 a 151.27 b 159.50 ab 176.02 a 145.68 a 153.73 a 152.95 a Guichao 2 83.72 a 86.04 a 93.91 a 131.29 b 161.73 a 163.69 a 127.07 b 139.46 a 148.41 a II-32B 89.32 b 109.54 a 114.86 a 162.52 a 166.74 a 184.31 a 155.90 b 178.68 a 186.06 a Teqing 99.70 b 110.16 b 127.81 a 155.11 a 172.41 a 172.32 a 147.48 c 162.21 b 177.00 a R379 86.56 a 100.41 a 98.20 a 127.60 b 142.23 a 152.40 a 118.40 b 131.65 a 127.62 ab 9311 91.19 b 106.94 a 117.20 a 160.74 a 173.83 a 170.69 a 149.48 b 162.77 a 167.92 a Jiangan 94.39 b 103.09 a 104.54 a 110.10 b 118.95 b 137.43 a 103.25 b 115.53 a 123.70 a

**Table 2.** The lodging index of twelve *indica* rice cultivars on all the sowing dates across two locations

a Within a row for each year, means followed by the same letters are not significantly different de-

**Table 3.** The △BM of twelve *indica* rice cultivars on all the sowing dates across two locations and

**(%) Xindu/2015 Ezhou/2017 Ezhou/2018** 

**SD1 SD2 SD3 SD4 SD5 SD6 SD7 SD8 SD9** 

Chuan 106B 2644.12 a b 2039.94 b 1346.41 c 1150.50 a 671.60 b 349.58 c 1177.42 a 758.29 b 517.23 b 63.19 345B 2501.73 a 1790.85 b 1642.24 b 922.84 a 617.56 b 477.06 b 1078.02 a 926.45 a 642.13 b 56.76 Huanghuazhan 3149.41 a 2629.95 ab 2036.62 b 736.20 a 341.49 b 146.86 c 1082.53 a 660.49 b 473.25 b 86.74 Jinlongsimiao 3123.09 a 2740.98 a 2137.34 b 811.33 a 550.77 ab 292.45 b 1176.19 a 733.90 b 635.89 b 76.76 Chuanxiang 29B 2600.97 a 2163.80 b 1957.99 b 540.39 a 416.68 ab 264.07 b 684.26 a 481.05 ab 250.41 b 88.95 Chenghui 3203 3174.04 a 2443.57 b 2444.77 b 850.97 a 591.92 ab 300.71 b 1003.42 a 696.71 b 695.78 b 76.57 Guichao 2 2213.49 a 2108.17 a 1613.65 b 897.83 a 420.38 b 353.33 b 1046.41 a 725.54 b 551.51 b 64.28 II-32B 1793.73 a 1436.09 ab 1176.57 b 480.55 a 354.43 ab 159.34 b 559.40 a 302.48 ab 133.49 b 85.05 Teqing 1891.21 a 1511.49 b 1039.69 c 586.78 a 329.64 b 312.78 b 703.07 a 451.53 b 252.74 c 73.69

△**BM (g cm) CV a**

**Lodging Index (%)** 

termined by the Tukey test at 5% probability level.

and three years.

three years.

**Cultivars** 

**Cultivars** 


**Table 2.** The lodging index of twelve *indica* rice cultivars on all the sowing dates across two locations and three years.

<sup>a</sup> Within a row for each year, means followed by the same letters are not significantly different determined by the Tukey test at 5% probability level.



<sup>a</sup> CV, coefficient of variation of the <sup>4</sup>BM across the nine sowing dates. <sup>b</sup> Within a row for each year, means followed by the same letters are not significantly different determined by the Tukey test at 5% probability level.
