Breeding new maize (Zea mays L.) varieties resistant to Fusarium ear rot is necessary, because the disease can cause contamination of the harvested grain with fumonisin, a mycotoxin. To better evaluate the resistance of maize to disease and fumonisin accumulation, we assessed a Fusarium inoculation method in field experiments conducted on inbred maize lines and F₁ hybrids from 2011 to 2013. This was done by (1) injecting a suspension of Fusarium spp. spores into the maize ears and, six weeks later, (2) calculating a disease index and measuring the fumonisin concentration. There were significant differences among the maize lines in disease indices, regardless of the experimental year and under both natural infection and inoculation, but not always in the fumonisin concentrations. Genetic lines with similar disease indices sometimes had different fumonisin concentrations. A remarkable positive correlation was found between the fumonisin concentrations of F₁ hybrids and their parental lines. Because the severity of disease symptoms did not necessarily correlate with actual toxicity, the fumonisin concentration of inoculated maize ears should be adopted as the best indicator of disease resistance in the steadily and rapidly growing field of hybrid maize breeding.

To elucidate the effects of the silk tree, Albizia julibrissin Durazz., a pioneer legume tree, on chemical characteristics of soil and grasses, I compared the nutritional contents of surface soil and aboveground grass biomass beneath and beyond the canopies of isolated silk trees. Nitrate-N, MgO, and the phosphate absorption coefficient in the surface soil were significantly higher, and total N, CaO, and cation exchange capacity were marginally higher beneath the canopy than beyond it. Crude protein, Mg, net energy maintenance, organic cellular content + organic a fraction, and crude fat in grasses were significantly higher beneath the canopy. Fibrous components were significantly higher, and dry matter ratio and phosphate were marginally higher beyond the canopy. Chemical components which were higher in the soil beneath the canopy, such as N and Mg, were also higher in grasses beneath the canopy. However, phosphate in grasses was only marginally higher beyond the canopy in spite of the significantly higher phosphate absorption coefficient in the soil beneath the canopy. These results suggest that A. julibrissin contributes to fertilization of soil through N fixation by root nodule bacteria and the uptake of minerals by the deep roots from the subsoil and their return in litter to the surface soil, thus improving the feed characteristics of grasses growing beneath its canopy.

The future situation of double cropping (DC) of corn (Zea mays L.) in Japan’s Kanto region was predicted based on the data simulated with the MRI-CGCM3 climate model and representative concentration pathways (RCP) 4.5 scenario. Annual effective cumulative temperatures (ECT, 10°C basis) in 2040 and 2090 were calculated for every third grid square (approximately 1 km×1 km) of the Kanto region, as a mean value between 2031 and 2050, and between 2081 and 2100, respectively. The areas suitable for corn DC were distinguished as two types of areas : one was the area in which ECT was higher than 2,300°C and corn DC was possible. The other was the area in which ECT was higher than 2,530°Cand high quality forage of which the dry matter ratio would be higher than 30% could be produced both in the first and the second cropping. It was predicted that, until 2040, the areas in which ECT values exceeded 2,300°C would expand to the central parts of the Kanto region (south areas of Tochigi Prefecture and Ibaraki Prefecture), and that, until 2090, the areas in which ECT values exceeded 2,530°C would expand to the central parts of the region.

This experiment was carried out to investigate in situ dry matter rumen degradability (ISDMD) of extruded brown rice (EBR) and extruded whole rice with hulls (EWR). The ISDMD was measured using the in situ nylon bag technique (incubation times : 0, 3, 6, 9, 12, 24 and 48 hours). A single-screw dry extruder was used to process the rice. The EBR, EWR, brown rice (BR), whole rice with hulls (WR) and barley were ground (2mm) and incubated in the rumen of two Japanese black cattle fed forage and concentrate in a ratio of 1 : 4 on a dry matter basis. Neutral detergent fiber contents of BR and WR decreased, whereas non-fibrous carbohydrate contents increased, with extrusion processing. The effective degradability (passage rate, 5%/hour) of dry matter from WR increased from 56.6% to 78.9% with extrusion. Results suggest that the utilization of rice by beef cattle are improved with extrusion.