Kenaf (Hibiscus cannabinus L.) is a potential alternative forage crop. The objective of this study was to examine the effect of cutting height on the yield in kenaf, cv. ‘Everglades 41’ harvested two times in a single growing season under upland and lowland field conditions. In Exp. 1, to clarify the optimum cutting height at the 1st cutting, we cut kenaf plants at a height of 15, 20, 25, 30 and 35 cm, and measured fresh and dry weights of the 1st-cut and the regrowth of the cut plants in pot experiments. In Exp. 2, kenaf plants grown under paddy field conditions were cut at a height of 25 cm in 2006, and 20 cm in 2007; while the plants grown in the upland field, were cut at a height of 20, 25 and 30 cm in both 2006 and 2007. In Exp. 1, no significant differences in the sum of the aboveground yield in the 1st cutting and regrowth plants among the different cutting heights. However, the yield of the plants cut at 25 and 30 cm tended to be higher than that of the plants cut at other heights. In Exp. 2, the regrowth rates after the 1st cutting in the upland field were extremely low (3.0∼3.7%), and some irrigation water was needed after cutting at lower than 30 cm. Under the paddy field condition, however, although kenaf seedlings were transplanted to a water-logged paddy field with water at about 5cm depth of water, kenaf plants showed a regrowth rate of 100% and 97.4% in 2006 and 2007, respectively; and, they had a higher crude protein content. In addition, the low precipitation in summer did not severely affect the growth of kenaf in paddy fields differing from that in the upland field. Therefore it was estimated that kenaf could be produced as forage by harvesting two times a year in the paddy field.

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Genetic and environmental factors in rice yield formation were analyzed using the data of the performance test for breeding conducted at the NARO Tohoku Agricultural Research Center obtained during a 14-year period. Transplanting and direct seeding with standard fertilization conditions were conducted with the good tasting varieties “Akitakomachi” and “Hitomebore”, high yielding variety “Fukuhibiki” and good tasting variety suitable for direct seeding “Moeminori”. Transplanting and direct seeding with high fertilization conditions were conducted with “Fukuhibiki” and the large grain high yielding variety “Bekoaoba”. Although the yield of “Moeminori” was not significantly different from that of “Hitomebore” in transplanting, that of “Moeminori was significantly larger than that of “Hitomebore” in direct seeding because of less lodging. Although the yield of “Bekoaoba” was not significantly different from that of “Fukuhibiki”, the average yield for 12 years was 3.4% higher in “Bekoaoba” than in “Fukuhibiki” in transplanting with high fertilization. The yield was closely correlated with the number of panicles and total dry weight. The correlation of yield with climate factors; average temperature and sunshine hours in June, July and August were investigated. In three of four varieties in transplanting with standard fertilization, a significant relation was observed between the yield and sunshine hours in Jun. The yield was not clearly correlated with other climate factors. These results suggested that the longer sunshine hours during vegetative growth increased the number of panicles and total dry weight, resulting in a high yield. The generality and specificity of these results need to be examined using the data of a yield test obtained at various places in Japan.

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Excess moisture injury is a serious constraint for common wheat production in Japan. We hypothesized that the excess moisture injury (EMI) is mainly caused by water and nutrient deficiency due to inhibited root function, and thus aimed to examine if the basal application of controlled–release fertilizer (CRF) to surface soil and the top-dressing with quick-acting fertilizer would mitigate EMI. We used cv. Norin 61 for pot experiments for four years. Temporal waterlogging was imposed in the pots to cause EMI whose intensity was regulated by adjusting the water tables. The application of CRF to the 3 cm surface layer increased nitrogen uptake by the plants more than that to the 10 cm depth or deeper layer,irrespective of the degree of EMI. Thus top-dressing was found to be effective even after the symptom of EMI appeared, and it enhanced nitrogen uptake to the level equivalent to that in the plants top-dressed without EMI. The top-dressing not only enhanced nitrogen uptake by roots in a shallow layer but, in some cases, also promoted the function of roots injured by excess moisture to absorb the released nitrogen from CRF. We therefore conclude that a combination of basal application of CRF to the shallow layer and top-dressing of quick-acting fertilizer is an effective technique to mitigate EMI and promote recovery from such injury by utilizing the roots in the shallow layer that tend to maintain a relatively high function under excess moisture conditions.

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Tillers with two or more leaves just before snow (robust stems before wintering, RS) affect the ratio of effective tillers and the yield in winter wheat in Hokkaido. The relationship between the number of RS per plant and the leaf age shown by the number of leaves on the main stem before wintering (LA) was investigated; then the desirable LA for increasing the yield was estimated. There was no significant difference between the number of RS and stem length, but the yield components, number of ears per plant, grain weight per ear and number of grains per panicle, were significantly greater in the plants with a larger number of RS. Although there was no significant corelation between cultivation condition and the number of RS, the plants at LA5.0, 5.5 and 6.0 had 3, 4 and 5 RS, respectively. The seeding density of the plants at LA5.5 and 6.0 was 167 and 132 grains/m^-2, respectively. From the viewpoint of using the seeding machine, stable seeding at a rate of 132 grains/m^-2 would be difficult. The results indicated that LA affects the yield of winter wheat in Hokkaido, and the desirable LA is around 5.5.

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A low steely grain rate is important for obtaining a high quality hull-less barley. To determine the factors that are related to steely grain rate, we observed endosperm tissue structure and performed multi-regression analyses of the correlation of steely grain rate with several grain quality characters using grain samples of the hull-less barley cultivar “Mannenboshi.” Two sample groups from cultivation trials at Ehime Prefectural Research Institute of Agriculture in 2011 (21 samples) and 2012 (69 samples), and one group of samples from 21 farmers in the entire area of Ehime prefecture in 2011 were used in the experiment. In all of the three sample groups, the glassy grains were confirmed to have endosperm cells that were filled with matrix proteins around the starch granules. Based on the correlation analysis with steely grain rate, the grain-specific gravity showed significant correlations in all sample groups, and the grain protein content, known to be an influencing factor in formation of glassy grains, in all sample groups. Thus, the glassy grain rate was largely influenced both by the degree to which they filled the endosperm cells, as indicated by the grain-specific gravity and the amount of grain protein as the filler in the endosperm cells. Indeed, in all sample groups, the explanation ratios (R²⁾ for the steely grain rate was larger in the two factor regression model that included both the grain protein content and the grain-specific gravity as compared with the single regression model of grain protein content.

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In Japan, the high Β-carotene content of whole-crop rice silage makes it unsuitable as feed for beef cattle in the production of high quality beef. For the purpose of breeding a cultivar for whole-crop silage with low Β-carotene content, a rice line with light-colored leaves was selected from progenies obtained from artificial mutants of ‘Hoshiaoba’, a cultivar for whole-crop silage use. The selected line was designated ‘Tashukei 1066’ and its Β-carotene contents and agronomical characteristics were compared with those of ‘Hoshiaoba’. There were no significant differences in culm length, panicle number and dry weight between Tashukei 1066 and Hoshiaoba. However, at the heading stage, the Β-carotene contents of Tashukei 1066 was lower than that of Hoshiaoba, although the difference was not clear at the yellow ripening stage. At both stages, the SPAD readings of Tashukei 1066 were significantly lower than those of Hoshiaoba. In conclusion, further examination is necessary before Tashukei 1066 can be used practically as a low Β-carotene content cultivar, but this line is expected to be useful as a parental line for breeding of a cultivars with a low Β-carotene content.

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We analyzed the effects of climatic fluctuations on wheat (Triticum aestivum) cultivar ‘Norin 61’ grown by the same cultivation method on an experimental field in Saitama Prefecture from 1951 to 1996. The heading and maturity had become earlier and the number of days from heading to maturity increased during the 45 years. No trends were observed, however, in the culm length, yield, or yield components. Multiple-regression analysis was performed on the relationships between climatic fluctuations and the wheat growth and yield across the study period. The number of days from seeding to heading was significantly reduced by increase in mean air temperature from November to April. The number of days from seeding to maturity was also significantly reduced by the increase in mean air temperature for the same period and in May. The culm length was significantly increased under higher total precipitation from January to April and higher mean air temperature in March. Yield was reduced by higher mean air temperature from November to December and greater precipitation in the period from heading to maturity. The yield reduction was attributed to the reduced number of grains per spike due to the increased mean air temperature from November to December and increased precipitation in May. These results highlighted the number of grains per spike as a critical trait for stable wheat production against climatic fluctuations.

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We elucidated the correlation between temperature conditions and the brown rice quality of “Yamadanishiki,” a brewer’s rice cultivar. A strong correlation was observed between inspection grade and head brown rice yield ratio, with a tendency toward an increase in inspection grade with increased head brown rice yield ratio. The yield ratio of head brown rice with inspection grades of deluxe quality or higher was generally ≥85%. The inspection grade and head brown rice yield ratio were correlated with daily mean temperature during the grain-filling period, with a tendency toward a decline in inspection grade or head brown rice yield ratio at high temperatures. The correlation coefficient with daily mean temperature was particularly high during the mid-grain-filling period 11–20 days after heading. Daily mean temperatures during this period that resulted in inspection grades of deluxe quality or higher were ≤23.4°C for young seedlings and ≤24.1°C for seedlings in the mid-growth phase. The thousand-kernel weight was negatively correlated with the temperature 11–20 days after heading, and the percentage of milky white rice and white-back rice sharply increased when the daily mean temperature during this period was ≥26.5°C. A negative correlation was observed between protein concentration in brown rice; and white-back rice yield ratio and thus when the protein content of brown rice was high, the occurrence rate of white-back rice was lowered.

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[in Japanese]

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The property and effects of phosphorus in incinerated biomass as fertilizer were evaluated. Incinerated poultry manure contained 27.23% phosphate, and incinerated cattle manure contained 7.93% phosphate. Most of the phosphate in incinerated manure, 92.2% of the phosphate in incinerated poultry manure, and 99.3% of the phosphate in cattle manure was citrate soluble. On the other hand, hardly any water-soluble phosphate was contained in incinerated biomass. As a result, most of the phosphate in incinerated biomass is considered to be available phosphate. Komatsuna (Brassica campestris var. peruviridis) was cultivated in pots supplied with incinerated biomass or chemical fertilizer consisting of fused magnesium phosphate. The plant growth in the pots supplied with incinerated biomass was almost equivalent to or greater than that with fused magnesium phosphate. In the field experiments with komatsuna, there was no significant difference in growth, yield or fertilizer effect between the plants fertilized with incinerated biomass and those fertilized with magnesium phosphate. Thus, incinerated biomass was considered to be suitable substitute for phosphate fertilizer.

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