A Study on early vigor of rice genotypes under low-input culture
Grant-in-Aid for Scientific Research (C).
|Research Institution||KYOTO UNIVERSITY|
SHIRAIWA Tatsuhiko Kyoto University, Graduate School of Agriculture, Lecturer, 農学研究科, 講師 (30154363)
|Project Fiscal Year
1997 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 2000 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1997 : ¥1,800,000 (Direct Cost : ¥1,800,000)
|Keywords||Rice / Oryza sativa L. / Cultivar / Early vigor / Low input / Nitrogen / Weed competition / Echinochloa oryzicola Vasing. / イネ / 品種 / 初期生長 / 低投入 / 窒素 / 雑草競合 / Echinochloa oryzicola Vasing / Oryza satira L. / 窒素(ちっそ)|
This study was conducted to (1) evaluated variability of early vigor among divergent rice genotypes, (2) identify plant traits that cause differential early vigor, and (3) evaluate the significance for early vigor in the crop production processes. Divergent 63 genotypes were chosen for this study from improved and local cultivars of japonica, tropical japonica and indica.
1. Growth analysis of seedling growth
An intensive observation of the four cultivars was conducted under hydroponic culture and dry matter growth of seedlings was analyzed defining it the sum of heterotrophic growth (utilization of seed reserve, DW_h) and autotrophic growth based on photosynthesis (DW_a). The time course of DW_h was well described with a logistic
function with DW_<hMax> as a primary determinant of growth rate, while the change in DW_a was represented by an exponential function with RGR as a primary parameter for each genotype.
2. Variability of early vigor
The seedling growth to beginning of tillering varied among 63 genotypes from 190 to 590mg/pl. The above formula well represented their growth and DW_<hMax>, and RGR varied 9 to 22mg and 8.6 to 11.4mg g^<-1> (°Cd^<-1>), respectively. From a sensitive analysis, it was proved that variation of early vigor was more dependent on autotrophic than heterotrophic growth. RGR (determinant of heterotrophic activity) tended to positively correlate with the partitioning of dry matter to the aerial plant organs.
3. Significance of early vigor in competition with weed under field condition
Four contrasting cultivars were grown in the field with and without E.oyzicola as a competitor. Rice growth was evidently affected by competition from early growing period. During this period, the ratio reduction of DW was smaller in the cultivars that had superior early vigor.
Research Output (4results)