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.39, no.4, pp.401-408, 1970-12

被引用文献数

1

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Growing the rice plants under each condition of some possible combinations of the 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) at each stage of growth, the autliors examined their main effects and interactions on the percentage of sterile grains. 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 following day. The depth of water was kept in four cm. 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^2P. The results were summarized as follows; 1. At the differentiating stage of first bract primordia (T_3), all the main effects and their two-factor interactions were not significant (table 4). 2. At the middle differentiating stage of primary branch primordia (T_4), only the main effect of A_D was significant at 5% level. However, that was not considered to be important because the differences of the percentage of sterile grains among them were smaller than 3%(tables 3 and 4). 3. At the stage of reduction division of pollen mother cells (T_5), the main effects of A_D, A_N and P and all of their two-factor interactions were significant at 0.1 or 1% levels. Moreover, the effects of W_D, W_D × A_N and W_D × W_N were also significant at 5% level. The contour lines of each pefcentage of sterile grains based on A_D and A_N were straight and parallel with the line of mean air temperature for three day treatment (fig. la). On the other hand, the contour lines for six and nine day treatments were curve together (fig. 1b-c). 4. At the head emergernce stage (T_6), the effects of A_D, A_N, P, and A_N × P and A_N × P were significant at 0.1% level. However, for three day treatment, A_D and A_N didn't affect the percentage of sterile grains. For six and nine day treatment, A_D and A_N were effective and their contour lines of each percentage of sterile grains were curve (fig. 2b-c). 5. The optimum ranges between A_D and A_N to minimize the percentage of sterile grains for each mean air-temperature were found in all the cases in which the contour lines were curve. The lower the mean air-temperature became, the bigger the optimum range between A_D and A_N became in most cases. Moreover, the optimum combinations of A_D and A_N to minimize the percentage of sterile grains were found to be about 24-20℃ in all cases (fig. 1〜2).