We conducted field experiments during the period 2011-2014 to evaluate the efficacy of hairy vetch (HV) living mulch on weed control in stands of forage soybean cultivated without herbicides. Soybean seed was planted in June, without tilling, into HV sod that had been sown in September of the previous year. The HV sods were chopped by disc harrow, prior to soybean seed germination, with the gang angle adjusted to prevent overturning of the sod. The dead HV sod formed by this procedure suppressed weed growth effectively in fields where pale persicaria, common lambsquarters, or slim smooth pigweed dominated, but was less effective in a field dominated by barnyard grass. If the disc harrow procedure was carried out within four days of soybean planting, soybean germination was not disturbed. We also found that a planting density of soybean-less than 12000/ha-brought about an increase in weeds, and consequently reduced soybean yields.

We evaluated the farming of sudangrass both in experimental and farmer’s fields with conventional tillage or without tillage. Firstly, we evaluated the yield of sudangrass and weeds under three treatments: tillage, no tillage and no herbicides, and no tillage with glyphosate application at the seeding, in experimental fields. There were no differences in dry matter yield of sudangrass between tillage and no-tillage farming systems. However, in the first crop, weed yield was significantly higher under the no-tillage, whereas the growth of weeds was controlled under the no tillage with glyphosate application treatment. These results showed that sudangrass yield is not reduced by not performing tillage, and that applying glyphosate to the emergence weeds is effective for controlling weeds. Secondly, to estimate the laborsaving effect of farming without tillage, we compared the working time at seeding between the conventional-tillage and no-tillage farming systems in farmer’s fields. Conventional tillage farming took 0.46h/10a, whereas farming without tillage required only 0.37h/10a, thereby reducing the working hours by 23%. Moreover, farming without tillage decreased diesel fuel consumption by 68%. In conclusion, farming sudangrass without tillage is a useful practice for reducing labor costs without reducing dry matter yield.

Recently, the Japanese trade system is facing large changes due to the new Trans-Pacific Strategic Economic Partnership Agreement. To be competitive with imported goods from abroad, many industries are required to improve their production efficiency, including dairy and livestock farming. Development of new forage grass cultivars selected for high yield and quality has become an important method for increasing animal performance and productivity. Traditionally, selection of superior grass plants is based on subjective visual ratings by the breeder. Novel non-subjective selection methods have the ability to improve the accuracy and efficiency of selection. In this study, we tested whether using a UAV (drone) and image analysis can be used to enhance the efficiency and effectiveness of selection in a grass breeding program. Image analysis of a nursery containing orchard grass cultivars obtained from the UAV correlated (r > 0.8) with their first crop yield. An index based on visible wavelengths RGB showed high correlation with the degree of pathogen infection (rhynchosporium and black rust). These results indicate that combining the use of a UAV with image analysis can be helpful for the development of effective selection methods in a grass breeding program.

Tetraploid perennial ryegrass (Lolium perenne) is utilized as palatable grazing grass in Japan. The genome size of perennial ryegrass cultivars that was bred in Japan have not been reported yet, we estimated the genome size of 6 Japanese cultivars and a breeding line by flow cytometry in this study. As the results, the average genome sizes of the cultivars were varied in small range from 5487 to 5575 Mbp/C, and there was no significant difference. However, large genome size difference among individuals, at least 660 Mbp/C between minimum and maximum individuals, was observed in each cultivar and a breeding line. Based on fluorescence in situ hybridization analysis, one of the reason why the large difference arose was considered to be the existence of aneuploid. Seed productivity is commonly affected by aneuploidy, flow cytometry could be useful tool to reject aneuploids in breeding program of perennial ryegrass.