著者

柴田 和博 佐々木 一男 島崎 佳郎

出版者

日本作物學會

雑誌

日本作物学会紀事 (ISSN:00111848)

巻号頁・発行日

vol.42, no.3, pp.267-274, 1973-09

被引用文献数

2

---

Growing the rice plants under various conditions of some possible combinations of daytime air-temperatures (A_D : 26, 20 and 14℃), the daytime water-temperatures (W_D : 26, 20 and 14℃), the nocturnal air-temperatures (A_N : 20, 14 and 8℃), the nocturnal water-temperatures (W_N : 20, 14 and 8℃) and the number of days of treatment (P : 3, 6 and 9 days), the authors examined their main effects and interactions on the heading date. The rice variety "Eiko" was used. The daytime was settled for eight hours from 9.00 a.m. to 5.00 p.m. and the night-time was settled for sixteen hours from 5.00 p.m. to 9.00 a.m. of the next day. The water was kept four cm. in depth above the soil surface in pots. The experimental design was 3^5 factorial in 81 units (1/3 replicate) with one block and defining contrasts 1=A_DW_DA_NW_<N^2>P. The results were summarized as follows; 1. At the fourth leaf stage (T_1; the transplanting time), the main effects of W_D, W_N and P were significant at 0.1% level and all the other were not significant (table 2). And regardless of the difference of W_N, it was inferred that W_D of 21℃ hastened the heading date (fig. 1-T_1(P_3)). 2. At the seventh leaf stage (T_2; about ten days before the differentiating stage of first bract primordia), the main effects of A_D, W_D, A_N and W_N and the two-factor interactions of A_D × P, A_N × W_N and A_N × P were significant. The contour lines of each date of heading based on W_D and W_N were almost straight and parallel with the line of mean water-temperature for nine days treatment (fig. 1-T_2 (P_3)). On the other hand, the contour lines of each date of heading based on A_D and A_N were curved. And regardless of the difference of A_N, it was inferred that A_D of 20℃ hastened the heading date (fig. 2-T_2 (P_3)). Moreover, T_2 was considered to be the most sensitive stage to temperature, because the heading date and the total leaf number on the main stem were most variable by both air- and water-temperature among all the treatment stages. 3. At the stages of nine leaves (T_3; the differentiating stage of first bract primordia) and ten leaves (T_4; the middle differentiating stage of primary branch primordia), the main effects of each factor and their interactions were similar to those of T_2, but the strengths were weaker than those of T_2 (table 2, 3 and 4). 4. At the thirteenth leaf (flgg leaf) stage (T_5; the stage of reduction division of pollen mother cells), the main effects of A_D, A_N and P and the two-factor interaction of A_N × P were significant greatly (table 2). The contour lines of each date of heading based on A_D and A_N were almost straight and parallel with the line of mean air-temperature (fig. 2-T_5 (P_3)).