Silica content of rice [Oryza sativa]-seedlings as affected by nursery bed soil-Rock Wool Mat
2006
Mori, S.(Yamagata-ken. General Agricultural Research Center (Japan)) | Fujii, H. | Ando, H.
Rock Wool Mat (RWM) is used by farmers as nursery bed (soil) for nurturing of rice seedlings, because the weight of RWM is lighter than that of typical nursery bed soil. The main composition of RWM is calcium silicate, implying that silica content of rice seedlings using RWM is higher than when using typical nursery bed soil. The dissolution of silica from calcium silicate depends on soil pH, however, the pH of RWM in the nursery is obvious. The objective of this study is to observe the effect of RWM on silica content of rice seedlings and pH of RWM during the nursery stage of rice plants. The results obtained are as follows : 1) The silicate content of rice seedlings grown using RWM is 47 g kg(-1), and this value is 15-20 g kg(-1) higher than that of seeding grown using typical nursery bed soil. 2) The silicate content of rice seedlings, grown with twice topdressed N and with thin cover soil, which has more than 100 mg kg(-1) available silicate, is more than 50 g kg(-1) and can be blast suppressive. (Fifty grams of silicate per 1 kg rice plant is the critical lent of content of silicate against blast disease.) 3) The pH value of RWM is maintained at around 4.2 to 4.5 during 2.2 to 2.5 of plant age in leaf number. This fact indicates that the dissolution of silicate from RWM is affected by pH of RWM.
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