Figure 1.
Rice lines with improved lodging resistance.
(A) Bending-type lodging resistance of selected lines evaluated in terms of cLr value. Data are means ± SD (n> = 3). (B) Gross morphology of the selected lines. First up to the second panel of the third row show T65 (original cultivar) and T65 mutant lines. MN-1 and MN-2 at the third row are Nipponbare mutants and MK-1 at the fourth row is a Kinmaze mutant, respectively. Bar = 20 cm.
Figure 2.
Breaking-type lodging resistance and culm morphologies of selected lines.
(A) Breaking-type lodging resistance evaluated in terms of bending moment at breaking. Data are means ± SD (n> = 3). The fourth internodes of MT-6 and MT-8 could not be evaluated due to short internode lengths. (B) Magnified view of the third internode cross-section of 7 lines showing high bending-moment-at-breaking value in comparison with original cultivars (T65, Nipponbare, and Kinmaze). Bar = 500 µm. (C) Relative culm thickness of each line. Thickness of the original cultivars is set as 1. Data are means ± SD (n> = 3). The uppermost to fourth internodes were measured.
Figure 3.
Plant height and agronomical traits of T65 and smos1.
(A to H) Each trait of smos1 was compared to that of its original cultivar T65. Data are means ± SD (n> = 3). **, n.s, significantly different at P<0.01, and not significant, respectively (two-tailed Student’s t-test).
Figure 4.
Selection of lines with high grain yield and improved lodging resistance from the F5 population of the smos1 and ST-4 cross.
(A) Procedure to select for high grain yield and improved lodging resistance. (B) Grain weight per plant of lines from the F5 population of the smos1 and ST-4 cross. Data are means ± SD (n> = 3). (C) Bending-moment-at-breaking values of line #1 and line #5 (n> = 3).
Figure 5.
Morphology, plant height, and tiller numbers of T65, smos1, ST-4, and LRC1.
(A) Gross morphology of plants at 30 days after heading. Bar = 10 cm. (B) Diagram for plant height. (C) Diagram for tiller numbers. Plant height and tiller numbers (n> = 3) were measured at 40 days after heading. Tukey’s test was conducted for panels (B) and (C).
Figure 6.
Panicle structure and yield-related traits of T65, smos1, ST-4, and LRC1.
(A) The gross panicle morphology of each line at 40 days after heading. Diagrams for (B) 1000-grain weight, (C) primary branch number, (D) grain number per panicle, (E) relative fertility, (F) grain weight per panicle, and (G) grain yield per hectare are also shown. Data are means ± SD (n> = 3). Tukey’s test was conducted for panels (B) to (G).
Figure 7.
Comparison of lodging resistance between T65, smos1, ST-4, and LRC1.
(A) Bending-type lodging resistance was analyzed in terms of cLr value. (B) Bending-moment-at-breaking lodging resistance. The uppermost to the fourth internode of each plant was used for analysis. Data are means ± SD (n> = 3). Tukey’s test was conducted for each panel.
Figure 8.
Culm morphology and culm strength of T65, smos1, ST-4, and LRC1.
(A) Culm cross-sections from the uppermost (1st) to the fourth (4th) internodes of the main culms. Bar = 5 mm. (B) Cross-sections of the fourth internode showing the culm thickness of each plant. Bar = 1 mm. (C) Culm thickness of the fourth internodes of each plant (n = 3). (D) Culm diameter measured from the uppermost to the fourth internode of the main culms (n = 3). (E) Section modulus and (F) bending stress of each plant (n = 3). Tukey’s test was conducted for panels (C) to (F).