Growth inhibition with yellowing of rice plant on the manganese excessive paddy fields in Shimane prefecture, Japan, 1: Symptom and occurrence factors
2007
Noda, S.(Shimane-ken. Agricultural Experiment Station, Izumo (Japan))
The causes and characterization of growth inhibition with yellowing of rice plant were investigated which had occured on the manganese excessive paddy fields, in the Kanagi District, Shimane Prefecture, Japan. The results obtained are summarized as follows: 1. This regional growth disorders of early-planted rice was severe and peculiar, causing yellow stunting of lower leaves and no increase in stem number after approximately 30 days of transplanting. 2. The inorganic component in a leaf blade appearing yellow was characterized by high content of Mn, Fe and low content of N, P and K. 3. This regional paddy fields or wild land were characterized by high content of easily reducible manganese in soil. 4. The disorder with yellowing of lower leaves was able to reappear by cultivation experiment in small pots containing excess manganese soils on the spot paddy field or wild land supplied with organic matter and was characterized by high content of Mn, Fe in soil solution. 5. Under submerging condition which was produced with only formation of Mn and no Fe in a weakly reduced environment, rice plants was severely injured by high conent of Mn in soil solution, but yellowing of leave was not appeared. It is considered, based on these findings, that growth disorder with yellowing results from iron toxicity which iron-excluding power is inhibited by metabolic activity of root inhibitors, such as high content of Mn in soil solution.
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