Effects of Planting Date on Yield, Yield Components, and Chemical Compositions in Rice Plants

Abstract

Rice cultivars, Tainung 67 (TNG 67) (Japonica) and Taichung Sen 10 (TCS 10) (Indica), were grown in six different times under natural conditions at the experimental farm of the Taiwan Agricultural Research Institute (TARI) at Wufeng, Taichung to investigate the relationships among climatic factors (air temperature, relative humidity, solar radiation and precipitation.), yield and chemical compositions (amylose, free sugar, crude protein and ash), and to establish the forecasting model for rice production. The climatic factors from the second crop season of 1997 to the first crop season of 1998 were investigated in Taichung area. The results indicated the trends of changes in temperature, solar radiation and precipitation were from high to low in the second crop season while from low to high was found in the first crop season. The relative humidity ranged between 80% and 96% for both crop seasons. In the second crop season, the late transplanted TNG 67 had higher yield (6,182.8 and 6,013.7 kgha^(-1)) and higher chemical composition contents (amylose and sugar) while the early transplanted TCS 10 had higher yield (6,208.8 and 6,136.5 kgha^(-1)) and lower chemical compositions. In the first crop season, TNG 67 and TCS 10 had higher yield of 6386.5 Kgha^(-1) and 6328.7 kgha^(-1) under early transplanting condition. Both cultivars transplanted in later dates produced higher chemical composition contents of crude proteins and ash (P, Ca, Fe, etc.). The chemical compositions of TCS 10 are higher than those of TNG 67 except the free sugar in the first and the second crop seasons. There were significant differences among transplanting dates and cultivars for yield, yield components and chemical compositions. In the first and the second crop seasons, the yield and the amylose of both cultivars showed highly correlated with the following climatic factors: X1 (accumulated temperature), X2 (mean temperature), X5 (solar radiation) and X7 (mean precipitation). The following equations of Y=60.15+0.42 * X2 and=Y1=55.76+0.57 * X2 were derived to express the relationship between the yield (kgha^(-1)) and the climatic factors during the tillering period in the first crop season for TNG 67 and TCS 10 respectively. The relationship between the yield and the climatic factors during the tillering period in the second crop season for TNG 67 and TCS 10 can be expressed as Y1=32.72-0.91 ** X2 and Y1=54.62+0.81 ** X2, respectively. The relationship between the amylose content (Y2: %) and the climatic factors during the grain filling period in the first crop season of 1998 for TNG 67 and TCS 10 can be represented as Y2=78.26-0.93 ** X2 and Y2=12.68-8.81 * X2, respectively. The relationship between the amylose content and the climatic factors during the grain filling period in the second crop season of 1997 can be expressed as Y2=10.32-0.85 ** X1 and Y2=6.26-0.65 * X1, respectively.