Effect of soil moisture conditions during the period from late autumn to early spring on the freezing tolerance of the Japanese chestnut (Castanea crenata Sieb. et Zucc.)
2015
Sakamoto, D. (Institute of Fruit Tree Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki (Japan). Plant Physiology and Fruit Chemistry Division) | Inoue, H. | Kusaba, S.
This study was conducted to determine the effect of soil moisture during the period from late autumn to early spring on the seasonal change in freezing tolerance of the Japanese chestnut cultivar 'Porotan'. Two-year-old trees planted in pots filled with gray lowland soil were used in this study. Soil moisture, based on the volumetric water content in the pots, was maintained at 15%, 25% and 40% by irrigation using amplitude domain reflectometry. The advance of cold hardening in autumn and delay of cold dehardening in spring were induced by the 15% and 25% soil moisture treatments under natural temperature conditions. At the same time, the highest total sugar content in the current season's shoots (CSSs) in the 25% soil moisture treatment was correlated with a delay of cold dehardening in spring. High soil moisture (40%) resulted in an increase in the water content of CSSs and a rapid decrease in freezing tolerance during the cold dehardening period. These results suggested that dry soil was responsible for the high sugar content and low water content in CSSs of chestnut trees in winter and resulted in the prevention of freezing injury. Our results also indicated that the effective soil moisture conditions for preventing freezing injury of 'Porotan' Japanese chestnut might be below 25% in the case of gray lowland soil.
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