Japanese nursery companies recently marketed three medium-maturing Italian ryegrass cultivars. ‘Tachisakae’ and ‘Yukitsuyoshi’ were sold as snow-endurant cultivars; ‘Fūjin’ was sold as a lodging-resistant cultivar. We investigated the yield performance, lodging-resistance, and snow-endurance of these new cultivars in cold climates, including an old snow-endurant cultivar ‘Nagahahikari’ and an old lodging-resistant cultivar ‘Hitachihikari.’ All tested cultivars showed high yields. The two latest snow-endurant cultivars, ‘Tachisakae’ and ‘Yukitsuyoshi’, are therefore suitable for cold climates. In highland areas with over 100 days of snow cover, ‘Yukitsuyoshi’ particularly demonstrated equally good snow-endurance as that of ‘Nagahahikari’. However, ‘Yukitsuyoshi’ and ‘Nagahahikari’ were lodging in early heading stage, whereas ‘Tachisakae’ showed slightly better lodging-resistance than ‘Yukitsuyoshi’ and ‘Nagahahikari’. It is thus desirable that snow-endurant cultivars should acquire the same degree of lodging resistance as the ‘Fūjin’ and ‘Hitachihikari’ cultivars.

Additional potassium fertilization is an effective measure for reducing radioactive cesium (RCs) transfer from soil to grass. However, increased potassium fertilizer use is often avoided as it may increase livestock disease risk. We conducted a two-year study of eight grass species and determined that transfer factor and pasture potassium content of festulolium (× Festulolium Braunii) and tall fescue (Festuca arundinacea Schreb.) were consistently lower than that of orchardgrass (Dactylis glomerata L.). The generalized linear model analysis indicated that the transfer factor and grass potassium content compared to orchardgrass were 52.2% and 86.3% for festulolium and 35.6% and 84.8% for tall fescue, respectively. These two grass species have high reliability as low RCs-uptake species, and therefore, changing the grass species from orchardgrass to festulolium or tall fescue can be an effective strategy for reducing RCs transfer without increasing the grass potassium content.

Unmanned aerial vehicles (UAVs) used in combination with structure from motion (SfM) data analysis are expected to be an effective method for estimating crop height without human intervention. Subtraction between a digital surface model (DSM) and a digital terrain model (DTM) was utilized to calculate crop height. DTM is normally estimated before planting or after harvest. Real-Time Kinematic-Global Navigation Satellite System (RTK-GNSS) can provide accurate georeferencing for better crop height estimations without the need for Ground Control Points. This study evaluated location errors by UAV-SfM between check points and estimated ones, comparing SfM settings and sunshine conditions. Adjusting the SfM settings with RTK-GNSS data improved both horizontal accuracy and vertical precision. Cloudy conditions improved vertical accuracy when adjusting the SfM settings with RTK-GNSS data. In conclusion, our best results were achieved on cloudy days.