2017 Volume 86 Issue 1 Pages 50-55
An indica-dominant high-yielding rice cultivar Hokuriku193 having a semi-dwarf gene often shows reduced seedling length and light seedling weight under low temperature conditions. Thus, we analyzed the improvements in the seedling length and weight by several nursery management methods combined with N top-dressing. Mulch heating treatment, covering seedlings above 40 cm with transparent plastic and leaving 3–4 cm of the bottom side of the plastic sheets open, increased seedling length by 3.5 cm, and maintained the seedling weight the same as or greater than the seedlings grown by the usual nursery method. The seedlings after N top-dressing showed greater seedling length, and heavier weight, and higher N content. Water depth of 5 cm during the nursery period increased seedling length by 2.9 cm, compared with the usual depth of 2 cm. Water depth of 5 cm did not significantly decrease seedling weight. The on-farm trial in cool highlands suggested that the increased length and N content of the seedlings improved the early biomass production after machine-transplanting and also decreased vacant hills.
