The Agri-Reconstruction Project and Rapeseed Project for Restoring Tsunami-Salt- Damaged Farmland After the GEJE – An Institutional Effort - Post-Tsunami Hazard: Reconstruction and Restoration - page 296

Table 18.6 Plant height, yield of seeds and weight of a thousand seeds of the B napus lines

Salt-damaged
farmland

Salt-damaged
paddy fi led Control Standard fi eld

Plant height (cm)
N-119 168.9 163.9 144.7

Kizakinonatane 192.1 165.0 152.0 143-155

Yield of seeds (t/ha)
N-119 4.2 4.3 3.2

Kizakinonatane 7.4 5.5 5.8 3.5-4.1

Weight of a thousand seeds (g)
N-119 4.2 4.7 4.9
Kizakinonatane 3.8 4.2 3.6 4.3
Control: Graduate School of Agricultural Science/Faculty of Agriculture, Tohoku University; Salt-
damaged farmland: Sendai City Agricultural and Horticultural Center; Salt-damaged paddy fi led:
Wakabayashi Ward in Sendai City. Standard Field: Average of 5 years data at normal farmland Of
Tohoku Agricultural Centre (Ishida et al. 2007 )

All lines indicated a trend for reduction of plant length due to salt damage.
Although yields (t/ha) showed a tendency to be reduced, no statistically signifi cant
difference was seen between the trial plots (Table 18.6 ). Measured by thousand ker-
nel weight, N-119 showed absolutely no sign of impact from salt damage. The val-
ues for Kizakinonatane in the affected upland fi eld and affected wet rice fi eld are
almost equivalent to the values (Ishida et al. 2007 ) reported by the Tohoku
Agricultural Research Center, showing that suffi cient growth and seed harvest could
be expected even on farmland affected by the tsunami.
B. juncea lines judged by the pot experiments to be strongly salt tolerant showed
dramatically reduced yields in both the affected upland fi eld plot and affected wet
rice fi eld plot. Considering seed yields based on the trial cultivations, B. napus is
appropriate for salt-damaged farmland. It was believed that approximately standard
harvests could be expected from the cultivation of either the salt-tolerant N-119 or
Kizakinonatane on farmland in the vicinity of the trial plots.
It was also found from these trial cultivations that B. napus can easily adapt to
the climate in the area around Sendai City. At the same time, it was discovered that
the B. juncea lines used in the experiments could not be expected to give suffi cient
seed yields, perhaps due to snow damage and other reasons.

18.3.2.4 Elucidation of the Salt Tolerance Mechanism

Plants have protective mechanisms that act against environmental stresses such as
salinity, low temperature and aridity. These mechanisms work through genes that
come into play to provide stress tolerance (Chinnusamy et al. 2004 ). Several such
genes are already known with respect to Brassicaceae plants. The variation in gene
expression between the strongly salt tolerant B. napus N-119 and the weakly salt
tolerant kirariboshi was examined. When treatment with a high salt concentration