Kyoichi Shibuya

Agricultural use of porous hydrated calcium silicate: effect of porous hydrated calcium silicate on resistance of rice plant (Oryza sativa L.) to rice blast (Pyricularia olyzae).

Abstract The effect of porous hydrated calcium silicate (PS) application on the resistance of rice plants ( Oryza sativa L.) to rice blast (Pyricularia olyzae) was evaluated. Experiments were conducted in Andisol at the experimental farm of Tohoku University from 1993 to 1995. The blast infection in the PS plot was much less than that in the control plot. On the other hand, slag (commercial slag silicate fertilizer) used in our experiment had no effect on blast infection. The number of silicified bulliform cells, the main invasion site for rice blast, was increased 320-980% by PS application, but only 80% by commercial slag. These results imply that PS application is effective in preventing fungal infection through silicification of bulliform cells. The number of silicified bulliform and trichome cells increased exponentially with increasing content of the silicon in the leaf blade, whereas the number of silicified short cells, which are smaller than bulliform cells and trichomes, had no relation to the silicon content in the rice leaf blade. We may conclude that the application of porous hydrated calcium silicate for rice plants is effective in increasing rice blast resistance because PS increase the number of silicified bulliform cells.

Change of structure of porous hydrated calcium silicate by dissolution in paddy soil.

Abstract Change of the structure of porous hydrated calcium silicate material (PS) by dissolution both in paddy soil and under laboratory conditions was studied using a X-ray diffractometer and a scanning electron microscope. The main crystalline minerals of PS were 11 Å tobermorite and quartz. The X -ray diffraction peaks of calcite (CaCO3) appeared at 14 d after transplanting (DAT) in paddy soil and their area increased with increase of the incubation time, whereas the area of the peaks of tobermorite decreased. The peaks of tobermorite disappeared at 53 DAT. The shape of PS, however, remained even at 120 DAT. It was suggested that the original shape of tobermorite was replaced by that of the silica skeleton. This silica skeleton with a large surface area was assumed to lead to a continuous supply of silicon to rice plants throughout the growing period. X-ray diffraction patterns of PS after incubation under laboratory conditions indicated that CO2 and moisture are required for the dissolution of tobermorite. Tobermorite reacts with H2C03 to produce calcium carbonate and silica gel.

Effects of polyolefin-coated fertilizer containing NPK and micro-elements on copper deficiency in barley and wheat in acid high humic Andisol

Pot experiments on barley (Hordeum vulgare L. Nijo) and wheat (Triticum aestivum L. Shirane) were conducted in a green house to evaluate the efficiency of co-situs band application of polyolefin-coated controlled availability fertilizer containing NPK and micro-elements such as Cu, Zn, Fe, B, Mn and Mo (CAF-ME) and seed of barley or wheat on the amelioration of copper (Cu) deficiency of those plants in Kawatabi acid high humic Andisol. A physiological disorders such as white twisting leaves, no heading plant, straight head without grains etc was observed in barley and wheat grown on the soils without Cu application and few grains were obtained from these plants. The plant height, dry matter, number of ears, number of grains and 1000 kernel weight of both barley and wheat were significantly improved by copper sulfate (CS) or CAF-ME application. The barley and wheat treated with CAF-ME reached almost the same grain yields as those treated with CS even at the rate of 1/16 of Cu applied in CS treatment. It was concluded that co-situs application of CAF-ME and seed more efficiently alleviates Cu deficiency of barley and wheat than the broadcasting of CS in acid high humic Andisol.

Characteristics of Vegetative Propagation of Common Comfrey (Symphytum officinale) as a Weed in Crop Fields.

薬用, 食用あるいは飼料作物として一時期盛んに栽培されたコンフリー (Symphytum officinale L., 和名: ヒレハリソウ) は, 近年その需要が減少したため放置され雑草化している。そこで雑草害が問題となっている圃場でヒレハリソウの発生と発育状況を調査した。1) 調査した圃場にはさまざまなサイズあるいは生育段階のヒレハリソウ個体が混在し優占群落を形成していた。そのうちの開花期個体では, 栄養成長期個体に比べて草高と広がりが大きい傾向にあった。2) 圃場に発生したヒレハリソウは作土中に残存した地下部器官の断片に由来し, 茎基部の短縮茎を持つ個体と持たない個体に分けることが出来た。前者は開花期に達していたが, 後者は栄養成長期にあり, 芽の先端が地表面に到達していない個体もあった。3) ジャガイモを作付した畝跡に発生したヒレハリソウは畝間跡に発生したものより繁殖体の埋没程度が浅く, 地上部重の大きいものが多かった。土壌中の地下部器官断片から, 新たに形成された全器官重のうち新地下器官重の占める割合と地下器官断片の埋没深度との間には高い正の相関が認められた。