Double cropping (DC) of corn (Zea mays L.) can be applied to produce high-quality whole crop silage twice a year. In this study, recent expansion of areas suitable for corn DC in the Japan’s Kanto region was investigated and the future situation was predicted. The effective cumulative temperature (ECT, 10°C basis) from April to December during the period from 1980 to 2009 was calculated for every third grid square (approximately 1km × 1km), and the decadal average ECT for the 1980s, 1990s and 2000s was calculated for all squares. Areas suitable for corn DC were taken as those with ECT values exceeding 2,300°C. In the Kanto region, the ratios of areas suitable for corn DC in the 1980s, 1990s and 2000s increased from 2.6% to 13.8% and 20.0%, respectively. Using a Meteorological Research Institute (MRI) model, the potential increase in mean temperatures until the 2080s was estimated. With data from the 1980s and 1990s as a base, the results suggested that mean temperatures would be 1.2°C and 2.3°C higher in the 2040s and 2080s, respectively, indicating that 44% and 60% of the Kanto region will be suitable for corn DC in the 2040s and 2080s, respectively.

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Maize field yield and feed composition contents at the milk-ripe stage were estimated using multivariate analysis of hyperspectral (radiance spectral, first-derivative spectral) data at the yellow-ripe stage obtained through aerial remote sensing. Results show that when radiance spectral or first-derivative spectral data in the observed wavelength range (400-1,000nm) were used, R²_cv between the measured value and the estimated value was a maximum of 0.18. The evaluation index (EI) rank was D. For EI of more than C, the method can be inferred as sufficiently accurate for practical use. With a selected waveband, however, R²_cv was a maximum of 0.72 (P<0.05) and the EI rank was high at B. Furthermore, for a selected waveband, better improvement in estimation precision was achieved using first-derivative spectral data than when using radiance spectral data. Applying waveband selection and the first-derivative to spectral information observed from aerial remote sensing is an especially useful technique for aerial remote sensing where soil exposure and mixed pixel signals present difficulties. The yield and ether extracts (EE) increase at a fixed rate from the milk-ripe stage to harvest time, although crude protein (CP), organic cell wall (OCW), and crude ash (CA) decrease at a fixed rate. Results show that the spatial distribution of yield and feed composition content at harvest time can be estimated using these hyperspectral data at the milk-ripe stage.

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The experiments were carried out to investigate the chemical composition, digestibility and nutritive value of rapeseed (Brassica napus L.) meal (RM) expelled mechanically from the novel domestic double-low cultivar, ‘Kirariboshi’, and the production performance and metabolic profile of lactating dairy cows fed the RM as a substitution of soybean meal (SM). The examined RM contained more ether extract and less crude protein (CP) compared with SM, while the total digestible nutrition content was estimated to be similar to that of SM. The CP of RM was degraded more rapidly in the rumen of dairy cows compared with SM. The cross-over trial using eight lactating cows showed that the substituting of a half amount of SM with RM caused no effect on feed intake, body weight and condition, feed digestibility and lactation performance. Although the plasma content of total cholesterol was elevated (P = 0.038) when cows received the RM, the elevated level was still within a normal range. These results suggest that, on the basis of the feed characteristics of RM elucidated in the present study, the substitution of SM with RM at an appropriate rate exerts no adverse effect on the production performance and nutritional physiology of lactating cows.

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In this study, a mass measurement system for round bales of whole crop rice for a self-propelled bale wrapper was developed. This system consisted of a hydraulic pressure sensor, an oil temperature sensor, and mass analysis equipment. The measurement process involved mounting a round bale on a turntable and then measuring its mass using the maximum hydraulic pressure that could be applied by raising and lowering the turntable. This equipment can be used to measure the mass of round bales during the bale-wrapping operation. The measurement process for a round bale with an average mass of 243 kg requires 30 s. Under indoor examination of the error in measurement, the average error was 10 kg, however, under outdoor examination the average error was much larger, being 23.6 kg. When a correlation for the oil temperature was applied, the average error reduced to 12.7kg. Nonetheless, it is necessary to improve the measurement accuracy of this system.

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We examined the potential of an assay for assessing corn ear rot resistance induced by wound inoculation with Fusarium graminearum s.str. in five maize hybrids (relative maturity : 73-80 days) used for producing silage in Hokkaido Prefecture. The effects of the spore concentration and inoculation timing of inocula on the disease incidence were examined and the relationship between disease incidence and deoxynivalenol (DON) accumulation was clarified. Inoculation to the different maize hybrids with a spore suspension of 1-5 × 10⁵ spores/ml 10-15days after silking revealed differences in corn ear rot resistance among hybrids. Although a strong positive correlation was observed between disease incidence and DON concentration (P < 0.01), DON concentration was very high in some hybrids even though the disease incidences were similar compared with other hybrids. We propose that measurements of DON accumulation in infected plants should be incorporated into assays used to evaluate corn ear rot in maize.

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The authors designed and manufactured a high-speed and high-precision seed-releasing device that can be mounted on a corn planter that is adaptable to the small (10-30 a) no-tillage fields commonly found in Japan. The device is characterized by two inclined, rotating coaxial discs : separation disc and releasing disc. The separation disc has cells along its circumference that are used for separating seeds one by one, and the releasing disc has pockets along its circumference for releasing the separated seeds. To verify the functionality of the device, it was tested using forage dent corn seeds. The test results confirmed that the separation disc separated seeds one by one from the seed hopper, that the transfer of seeds from the separation disc to the releasing disc was smooth, and that the releasing disc released the transferred seeds from the bottom of the device to the ground in approximately equal intervals. Moreover, the results of performance comparison tests with an existing inclined plate-type seed-releasing device confirmed that the device developed in this study possessed higher accuracy than the existing seed-releasing device.

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Seed singulation accuracy tests of the device described in the first report (2014) were carried out to determine the effects of the angles of inclination of the discs, seed-releasing speed (times/s), and seed aspect ratio (length/thickness) of dent corn (Zea mays L.) seeds. Moreover, to verify the suitability of the device for guiding released seeds to the ground, we performed release accuracy tests with a trial structure constructed by assembling the device and a slit. The results of the seed singulation accuracy tests showed that the single-seed-separation ratio was approximately 98% when the angles of inclination of the discs ranged from 42° to 58°. Seed-releasing speeds in the range of 4-12 times/s were found to have a negligible effect on seed singulation. Furthermore, the seed singulation ratio decreased as the seed aspect ratio increased. The release accuracy test results showed that when the seed-releasing speed was set to 4-12 times/s and the tractor speed and seed spacing were assumed to be 2.16 m/s and 18cm, respectively, the standard deviation of the seed spacing that calculated by using the time taken and the horizontal distance covered by a seed before it reaches the ground level was approximately 1.5-3cm. The tested apparatus was suggested to be suitable for practical use.

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The water soluble carbohydrates (WSC) content of grass and mixed sward is an important factor in the fermentation quality of silage. At present, WSC measurement by anthrone method require time for analysis. In these regard, a quick analysis method of determining WSC using near infrared reflectance spectroscopy (NIRS) was used at precise calibration of the 2nd derivative spectrum of the wavelength region at 1500-1820nm and 2000-2220nm, and the calibration was determined by partial least squares regression. These conditions were determined by 152 forage samples of grass and mixed sward which include legume. As a result, the determination coefficient was 0.956 and standard error of calibration was 0.51. The Evaluation Index was 10.1 (A) and the ratio of standard deviation of reference data in the pre-dicted sample to SEP was 4.5. Using this method, the analysis time per sample was about a minute and with accurate precision.

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