Dutch variety DUNDEE, that produced more fruits per plant than Japanese variety Momotaro York, developed unusually massive adventitious roots from the stem of tomato, whereas Japanese variety developed lateral shoots instead of the adventitious roots. Both varieties increased starch content in the stem by fruit thinning. In this case, there were varietal differences only Japanese variety increased starch contents in 50 of fruits removal. These results suggested that translocation of assimilates to the fruits on Dutch tomato variety was more efficient than Japanese variety, however it was assumed that not only starch accumulation in the stem effected development of adventitious roots from the stem.

View full abstract

The giant tsunami of 2011 Great East Japan Earthquake completely destroyed a famous beautiful maritime pine forest, Takada-Matsubara (Rikuzen Takada city, Iwate). The number of trees damaged and lost was estimated to be 70 thousands. Most of the damaged trees were uprooted and flowed away by the tsunami, although some others lost only aboveground parts after trunk break. The serious damages can be explained by the height of tsunami (15.8 m at the Rikuzen Takada city gymnasium), which reached crown of the trees. This suggested that the tsunami struck directly to crowns of the pine trees and uprooted them. A PINE “Ippon-Matsu” that survived after the tsunami has 23-m clear bole length and the tsunami reached 1-m below its lowest branch. Pressure of the tsunami on the trunks of pine trees was estimated to be 100 ton. This was much lower than forces required for pulling down trees, which were estimated to be 183 ton. When a root system is submerged, however, stability of root anchorage decreases due to decreasing friction between the roots and the soil. In particular, when water flow of tsunami is fast and the soil is washed out, the stability of root anchorage would decrease remarkably. Although, in general, the stability of root anchorage is affected especially by outgoing tide of tsunami, impact of incoming tsunami is strong enough to pull down the trees when a tsunami is as big as that in 2011. Root exposure was not observed for Ippon-Matsu after the tsunami. In contrast, there was 60-100 cm accumulation of sand around the stem base. This area was an open forest and mechanical damage by flowing logs was not found on the Ippon-Matsu. Water flow and sand accumulation by tsunami are affected by topography and structures, and there is a youth hostel and dike of the Kesen river near the Ippon-Matsu. Thus, one of reasons the Ippon-Matsu was able to survive through the tsunami would be complex patterns of water flow caused by those structures.

View full abstract