Poster: Water Relations

Abs # 215: Application of short-term salt stress for production of high quality tomatoes

Presenter:	Araki, Takuya , araki@agr.kyushu-u.ac.jp
Authors	Araki, Takuya  (A)   Kitano, Masaharu  (B)   Wajima, Takahiro  (B)   Matsuoka, Takahisa  (B)   Ishikawa, Katsumi  (B)
Affiliations:	(A): Lab. of Plant Production Physiology, Grad. School of Bioresource & Bioenvironmental Science, Kyushu University (B): Faculty of Agriculture, Kochi University

In production of high quality tomato fruits, long-term treatment of salt or water stress is generally applied for high sugar concentration in fruits. However, the long-term stress treatment leads to small fruits and high incidence of blossom-end rot. In this study, short-term salt stress treatment limited for only the most active stage of fruit expansion was tried in a hydroponic system to increase mass accumulation into fruits depending on plant osmotic adjustment. During only two weeks salt stress treatment started from two weeks after pollination, EC of the nutrient solution was increased from 1.2 dS m-1 to 13.5 dS m-1 by adding salt made from deep sea water. After the start of the salt stress, leaf osmotic potential at predawn was decreased from -0.3 MPa to -0.7 MPa, which suggesting that plant osmotic adjustment was induced even by the two weeks salt stress. This short-term stress treatment decreased fruit fresh weight by only about 30% and remarkably accelerated mass accumulation into the fruits four to five weeks after pollination. Consequently, in the harvested fruits, the short-term salt stress brought 30% increase in dry weight and increase in fruit Brix to 9.1, while Brix in non-stressed fruits was 6.3. Furthermore, Na+, K+ and Mg2+ contained in the deep sea water salt were highly accumulated into the harvested fruits, and no blossom-end rot was found. From these results, the short-term salt stress is effective in mass accumulation into fruits and applicable to the production of high quality tomatoes.