Shigemi Tanakamaru

Farinose flavonoids are associated with high freezing tolerance in fairy primrose (Primula malacoides) plants

The deposition of surface (farinose) flavonoids on aerial parts of some Primula species is a well-documented but poorly understood phenomenon. Here, we show that flavonoid deposition on the leaves and winter buds may contribute strongly to preventing freezing damage in these plants. The ice nucleation temperature of fairy primrose (Primula malacoides) leaves covered with natural flavone was approximately 6 °C lower compared to those that had their flavone artificially removed. Additionally, farinose flavonoids on the leaves reduced subsequent electrolyte leakage (EL) from the cells exposed to freezing temperatures. Interestingly, exogenous application of flavone at 4 mg/g fresh weight to P. malacoides leaves, which had the original flavone mechanically removed, restored freezing tolerance, and diminished EL from the cells to pretreatment values. Our results suggest that farinose flavonoids may function as mediators of freezing tolerance in P. malacoides, and exogenous application of flavone could be used to reduce freezing damage during sudden but predictable frost events in other plant species.

Studies on the Seedling Emergence in Crops : Effect of compaction of covering-soil on the emergence in some cereals

This investigation was conducted to make clear the effects of compaction of covering soil on the strength of plumule-elongation and the seedling emergence in some cereals. The materials used were as shown in table 1. (1) In all the cereals used in this experiment, the strength of plumule-elongation under compacted covering-soil was stronger than that under non-compacted, irrespective of cultural temperature and plumule length (Table 2). (2) In each cereals, the area of cross section of plumule was larger in the plumule grown under compacted covering-soil than in the plumule grown under non-compacted, respectively (Table 3). Furthermore, bending strength of the former was stronger than that of the latter (Table 4). (3) Under compacted soil conditions, crops with long mesocotyl were highest in seedling emergence followed by crops with long coleoptile, and crops with short mesocotyl or short coleoptile (Figure 2).