The germination activity and the initial water absorption characteristics of Welsh onion seeds were examined at different levels of deterioration. Using data on the changes in moisture content of Welsh onion seeds, a non-linear least squares method was applied to an approximate solution of the diffusion equation. The constant for a given solid shape values (B1) of the diffusion model were estimated to be about 0.8. The data were fitted to the exact solution for the infinite plane sheet diffusion model using a non-linear least squares method. The measured results agreed with the calculated results. The specific volume changes of the sample were determined using particle density measurements at several moisture contents by a liquid-displacement method using a pycnometer. Using an empirical equation with three parameters that related moisture content and temperature to specific volume, the measured data agreed with the values calculated from the equation. The results of the comparison of aging effects among the three deterioration levels of Welsh onion seed showed that the water absorption rate of aged seeds was lower than the fresh seeds at all tested temperatures. Moreover, the aging effect appeared as lower volume expansions by water absorption, besides the increase of abnormal and non-germination seeds in the germination test.
The effects of combining atmospheric CO2 concentrations (360 vs. 700 μL L−1) and N fertilizer on the growth, yield and grain nutrients of a semi-dwarf, japonica rice (Oryza sativa L.) were examined by the use of artificially illuminated growth chambers. Throughout the growth period, elevated CO2 + high N promoted dry-matter production, and under elevated CO2, the optimum N level was even higher. Flowering occurred earlier under elevated CO2, but was delayed by higher N levels. The position of the flag leaf fell by one “slot” and the lengths of the culm and panicle decreased due to the elevated CO2. Elevated CO2 + high N enlarged the yield capacity in terms of the numbers of panicles and grains but higher yield did not necessarily occur, because of the decreased percentage of productive tillers. The effects of CO2 on the mineral content were complex, but under elevated CO2 + high N, two parameters (K + Mg, Mg/K) which indicate good rice quality were ameliorated.
Pilophorus typicus (Heteroptera: Miridae) is a candidate insect for biological control against agricultural pests such as aphids, whiteflies, and spider mites. This species has two genotypes in Japan, i.e., the northern and southern types, but it is difficult to differentiate them because of few morphological characters separating them. Artificial migration across the distribution range of each genotype may incur ecological and genetic risks. To conduct a prompt identification of the two genotypes, we developed the method of PCR-RFLP using the cytochrome oxidase subunit I (COI) region on mitochondrial DNA. The PCR product of the southern type yielded two DNA bands by the action of the restriction enzyme of Psi I, whereas that of the northern type gave only a single band on electrophoresis. Moreover, the PCR-RFLP using samples from many localities revealed that the restriction site of Psi I is well conserved within each type. These results suggest that the PCR-RFLP of the COI region provides the accurate and easy discrimination of the two genotypes of P. typicus.