Effect of temperature on viability and elongation of lateral bud of napiergrass (Pennisetum purpureum Schumach)

The effect of temperature on the viability and the elongation of lateral buds (LB) of napiergrass (Pennisetum purpureum Schumach cv. Merukeron) was examined and the storage of live stems during winter was also tried. LB of field-grown plants were alive when the daily minimum air temperature was 1°C, but died when it fell to -3°C. The viability of LB decreased to less than 50% by low temperature treatments (under zero, for 24 hours). The viability of LB of lower nodes was higher than that of upper nodes in all the treatments of low temperature. The minimum temperature at which field-grown ratoons could survive the winter was in the range from 0.9 to 4°C. By storing detached stems in the soil (60 cm in depth), 40% of LB survived the winter. LB of detached stems did not die nor elongate at 5°C of storing temperature. The activity of the starting of elongation of LB was the highest in the range from 25 to 40°C. From these results, it was concluded that the stems used as seeds and stocks in next year were made survive the winter by cutting field-grown stems before the minimum air temperature falls below zero and then storing them in the soil and such like where temperature can be kept about 5°C.